UVA toolkit



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100 - The 3n + 1 problem - ad hoc, simulation.
101 - The Blocks Problem - ad hoc, simulation.
102 - Ecological bin packaging - greedy, ad hoc.
103 - Stacking Boxes - DP, graph theory, longest path, DAG, sorting.
104 - Arbitrage - graph theory, all-pairs shortests paths, APSP, negative weight cycle, Floyd-Warshall (modified relaxation operation).
105 - The Skyline Problem - computational geometry, sweep line (or ad hoc: brute force, height map).
106 - Fermat vs Pythagoras - number theory, math, Pythagorean triples, Euclid's formula.
107 - The Cat in the Hat - trees, math, number of leaves and internal nodes.
108 - Maximum Sum - maximum 2D sum, maximum 1D sum, DP.
109 - Scud Busters - computational geometry, convex hull, point in convex polygon.
110 - Meta-Loopless Sorts - backtracking, permutations, insertion sort.
111 - History Grading - DP, LIS (modified) (or LCS).
112 - Tree Summing - backtracking.
113 - Power of Cryptography - math, n'th root of an integer (can use builtin pow-function).
114 - Simulation Wizardry - simulation, ad hoc.
115 - Climbing Trees - trees, tree traversal, lowest common ancestor.
116 - Unidirectional TSP - DP.
117 - The Postal Worker Rings Once - graph theory, Euler tour, shortest paths, SSSP, Bellman-Ford.
118 - Mutant Flatworld Explorers - ad hoc, simulation.
119 - Greedy Gift Givers - ad hoc.
120 - Stack of Flapjacks - greedy, sorting, stacks, queues.
121 - Pipe Fitters - geometry, grid packing.
122 - Trees on the level - ad hoc, tree traversal.
123 - Searching quickly - ad hoc, sorting.
124 - Following orders - graph theory, topological sort.
125 - Numbering Paths - graph theory, DFS, cycles, strongly connected components (or Floyd-Warshall/transitive closure).
126 - The Errant Physicist - ad hoc, polynomials, parsing.
127 - Accordian Patience - ad hoc, simulation.
128 - Software CRC - number theory, modulo, math.
129 - Krypton Factor - graph theory, DFS, brute force, backtracking.
130 - Roman Roulette - ad hoc, simulation, Josephus problem.
131 - The Psychic Poker Player - ad hoc, simulation, brute force.
132 - Bumpy Objects - geometry, brute force, triangles, angles (or convex hull).
133 - The Dole Queue - ad hoc, simulation.
134 - Loglan - A Logical Language - parsing, recursive decent parsing.
135 - No Rectangles - math, finite fields, cyclic permutations, primes.
136 - Ugly Numbers - ad hoc, brute force, no input.
137 - Polygons - computational geometry, intersection of convex polygons, cutting polygons by a straight line.
138 - Street Numbers - math, brute force, no input.
139 - Telephone Tangles - ad hoc, simulation.
140 - Bandwidth - backtracking, NP-complete, minimum bandwidth problem.
141 - The Spot Game - ad hoc, simulation.
142 - Mouse Clicks - geometry, simulation, ad hoc.
143 - Orchard Trees - computational geometry, point in triangle, brute force.
144 - Student Grants - ad hoc, simulation.
145 - Gondwanaland Telecom - ad hoc.
146 - ID Codes - permutations, math, sorting (or next_permutation in STL).
147 - Dollars - DP, coin change.
148 - Anagram Checker - ad hoc, string manipulation, backtracking.
151 - Power Crisis - ad hoc, simulation, Josephus problem.
152 - Tree's a Crowd - ad hoc, sorting, geometry.
153 - Permalex - strings, multinomial coefficients, permutations.
154 - Recycling - ad hoc.
155 - All Squares - ad hoc, recursion, geometry.
156 - Ananagrams - ad hoc, sorting.
159 - Word Crosses - ad hoc, strings.
160 - Factors and Factorials - number theory, primes, summations, math.
161 - Traffic Lights - ad hoc, simulation.
162 - Beggar My Neighbour - ad hoc, card games, simulation.
164 - String Computer - DP, edit distance (Levenshtein), printing solution.
165 - Stamps - brute force, backtracking.
166 - Making Change - DP (or greedy), coin change (or backtracking).
167 - Sultans Successors - backtracking, 8-queens problem.
168 - Theseus and the Minotaur - graph theory, simulation
170 - Clock Patience - ad hoc, simulation.
172 - Calculator Language - parsing, evaluating infix expressions, stacks.
183 - Bit Maps - ad hoc, recursion.
184 - Laser Lines - computational geometry, signed triangle area, collinearity,
186 - Trip Routing - graph theory, all-pairs shortest paths, APSP, Floyd-Warshall.
187 - Transaction Processing - ad hoc, simulation.
188 - Perfect Hash - ad hoc, hashing.
190 - Circle Through Three Points - geometry, circles.
191 - Intersection - geometry, lines, intersection, rectangles, line segment intersection.
193 - Graph Coloring - graph theory, brute force, backtracking, NP-complete, maximum independent set.
195 - Anagram - ad hoc, sorting, recursion.
196 - Spreadsheet - graph theory, topological sort.
200 - Rare Order - graph theory, topological sort.
201 - Squares - ad hoc.
202 - Repeating Decimals - cycle finding, decimal expansion.
216 - Getting in Line - graph theory, TSP, brute force, backtracking.
218 - Moth Eradication - computational geometry, convex hull.
227 - Puzzle - ad hoc, simulation.
231 - Testing the Catcher - DP, LIS (nonincreasing).
232 - Crossword Answers - ad hoc.
253 - Cube Painting - ad hoc, cyclic rotations, strings.
254 - Towers of Hanoi - ad hoc, bignum, bit manipulations, (or recursion).
256 - Quirksome Squares - ad hoc, number theory.
259 - Software Allocation - graph theory, max-flow.
260 - Il Gioco dell'X - graph theory, graph traversal, DFS.
263 - Number Chains - ad hoc, simulation, sorting, strings.
264 - Count on Cantor - math, binary search (or closed form solution), (like UVA 880)
270 - Lining Up - computational geometry, sorting, line gradients (slopes).
271 - Simply Syntax - parsing, recursive descent parsing.
272 - Tex Quotes - ad hoc.
275 - Expanding Fractions - cycle finding, decimal expansion (like UVA 202).
278 - Chess - ad hoc.
280 - Vertex - graph theory, traversal, reachability.
288 - Arithmetic Operations with Large Integers - simple math, bignum, repeated squaring, parsing, converting from infix to postfix.
290 - Palindroms <---> smordinilaP - ad hoc, simulation, number bases, bignum, addition, strings, palindromes.
291 - The House of Santa Claus - graph theory, traversal, DFS (Euler tour, brute force), no input.
294 - Divisors - number theory, sieve, primes, trial division.
297 - Quadtree - ad hoc, recursion.
299 - Train Swapping - sorting, counting inversions.
300 - Maya Calendar - ad hoc.
301 - Transportation - brute force, backtracking.
302 - John's Trip - graph theory, Euler tour.
303 - Pipe - computational geometry, farthest visible point, sorting, sweep line, line slope, line intersection.
305 - Joseph - ad hoc, simulation, Josephus problem.
306 - Cipher - permutations, repeated squaring (on permutations).
308 - Tin Cutter - geometry, flood fill, interval compression.
310 - L-System - graph theory, graph traversal, DFS.
311 - Packets - ad hoc, greedy, case analysis.
313 - Intervals - geometry, circle line tangents, sorting, line intersection.
314 - Robot - graph theory, BFS.
315 - Network - graph theory, articulation point, graph traversal, DFS.
320 - Border - ad hoc (or graph theory, graph traversal).
324 - Factorial Frequencies - ad hoc, bignum, addition.
325 - Identifying Legal Pascal Real Constants - parsing, recursive descent parsing.
326 - Extrapolation using a Difference Table - combinatorics, binomial theorem, difference tables.
327 - Evaluating Simple C Expressions - parsing, recursive descent parsing, abstract syntax trees, tree traversal.
331 - Mapping the Swaps - ad hoc, brute force.
332 - Rational Numbers from Repeating Fractions - ad hoc, gcd.
333 - Recognizing Good ISBNs - ad hoc.
336 - A Node Too Far - graph theory, graph traversal, BFS.
337 - Interpreting Control Sequences - ad hoc, simulation
340 - Mastermind Hints - ad hoc, sorting, simulation.
341 - Non-Stop Travel - graph theory, shortest paths, SSSP.
343 - What Base Is This? - number theory, number base conversion, ad hoc, brute force.
344 - Roman Digititis - ad hoc.
347 - Run, Run, Runaround Numbers - backtracking, permutations.
348 - Optimal Array Multiplication Sequence - DP.
350 - Pseudo-Random Numbers - cycle finding (Floyd's cycle finding algorithm).
352 - Seasonal War - graph theory, graph traversal, BFS, flood fill, number of components.
353 - Pesky Palindromes - ad hoc, strings, sets, string matching, palindromes.
355 - The Bases are Loaded - ad hoc, number base conversion.
356 - Square Pegs and Round Holes - ad hoc, geometry, number theory.
357 - Let Me Count The Ways - DP, coin change.
361 - Cops and Robbers - computational geometry, convex hull, point in polygon, point on line segment.
362 - 18,000 Seconds - ad hoc, simulation
369 - Combinations - ad hoc, combinatorics, number theory, binomial theorem.
371 - Ackermann Functions - ad hoc, simulation, Collatz conjecture, 3n+1 problem (same as UVA 100).
374 - Big Mod - number theory, modulo, repeated squaring (modular).
377 - Cowculations - ad hoc, number base conversion (base 4).
378 - Intersecting Lines - geometry, lines.
382 - Perfection - ad hoc, number theory,
383 - Shipping Routes - graph theory, BFS, shortest paths.
384 - Slurpys - ad hoc, parsing.
386 - Perfect Cubes - ad hoc, number theory, simple math, cube root, no input.
389 - Basically Speaking - ad hoc, number base conversion.
392 - Polynomial Showdown - ad hoc.
394 - Mapmaker - ad hoc, simulation.
400 - Unix Is - ad hoc, sorting.
401 - Palindromes - ad hoc, strings, palindromes.
402 - M*A*S*H - ad hoc, simulation.
406 - Prime Cuts - number theory, sieve, primes.
408 - Uniform Generator - cycle finding (Floyd's cycle finding algorithm).
409 - Excuses, Excuses! - ad hoc, string matching.
410 - Station Balance - greedy, sorting, graph theory, matchings, math.
412 - Pi - ad hoc, simulation, number theory, gcd.
413 - Up and Down Sequences - ad hoc.
414 - Machined Surfaces - ad hoc.
417 - Word Index - graph theory, BFS.
422 - Word-Search Wonder - ad hoc, string matching.
423 - MPI Maelstrom - graph theory, shortest paths, SSSP, Dijkstra, Bellman-Ford.
424 - Integer Inquiry - bignum, addition, simple math.
436 - Arbitrage (II) - graph theory, all-pairs shortest paths, APSP, Floyd-Warshall, negative weight cycle (like UVA 104).
437 - The Tower of Babylon - DP, LIS (non-standard).
438 - Circumference of the Circle - geometry, circle through 3 points.
439 - Knight Moves - graph theory, BFS.
440 - Eeny Meeny Moo - ad hoc, simulation, Josephus problem.
441 - Lotto - backtracking.
442 - Matrix Chain Multiplication - parsing, stacks, matrix properties.
443 - Humble Numbers - ad hoc, number theory.
444 - Encoder and Decoder - ad hoc.
445 - Marvelous Mazes - ad hoc, simulation.
446 - Kibbles 'n' Bits 'n' Bits 'n' Bits - ad hoc, number base conversion.
448 - Oops! - ad hoc, simulation, bitmasks.
450 - Little Black Book - ad hoc, sorting.
453 - Intersecting Circles - geometry, circle and circle intersection.
455 - Periodic Strings - ad hoc, string matching, string period.
457 - Linear Cellular Automata - ad hoc, simulation.
458 - The Decoder - ad hoc.
459 - Graph Connectivity - graph theory, connectivity, union-find.
460 - Overlapping Rectangles - computational geometry, rectangle-rectangle intersection (very easy).
465 - Overflow - bignum, parsing.
466 - Mirror, Mirror - ad hoc.
469 - Wetlands of Florida - graph theory, BFS, DFS, graph traversal, flood-fill.
473 - Raucous Rockers - DP, iterative, space saving tricks (USACO problem, chapter 3).
474 - Heads Tails Probability - ad hoc.
476 - Points in Figures: Rectangles - geometry, point in rectangle.
477 - Points in Figures: Rectangles and Circles - geometry, points in rectangles and circles.
478 - Points in Figures: Rectangles, Circles, and Triangles - geometry, points in figures.
481 - What Goes Up - DP, LIS.
482 - Permutation Arrays - ad hoc, sorting.
483 - Word Scramble - ad hoc.
484 - The Department of Redundancy Department - ad hoc.
485 - Pascal's Triangle of Death - bignum, number theory, no input.
486 - English Number Translator - ad hoc.
488 - Triangle Wave - ad hoc.
489 - Hangman Judge - ad hoc, simulation.
490 - Rotating Sentences - ad hoc.
492 - Pig Latin - ad hoc.
494 - Kindergarden Counting Game - ad hoc.
495 - Fibonacci Freeze - bignum, addition, Fibonacci numbers.
496 - Simply Subsets - ad hoc, set intersection.
497 - Strategic Defense Initiative - DP, LIS.
498 - Polly The Polynomial - polynomials, Horner's rule.
499 - What's the frequency Kenneth? - ad hoc.
507 - Jill Rides Again - maximum consecutive subsequence in 1D (maximum 1D sum), DP.
514 - Rails - ad hoc, stacks.
515 - King - graph theory, difference constraints, Bellman-Ford.
516 - Prime Land - number theory, sieve, primes, prime factorization.
517 - Word - cycle finding (Floyd's cycle finding algorithm).
523 - Minimum Transport Cost - graph theory, shortest paths, all-pairs shortest paths, APSP, Floyd-Warshall, printing the path.
524 - Prime Ring Problem - brute force, backtracking, number theory, sieve.
530 - Binomial Showdown - ad hoc, number theory, gcd, binomial theorem.
531 - Compromise - DP, LCS on strings.
532 - Dungeon Master - graph theory, BFS.
533 - Equation Solver - parsing, recursive descent parsing, AST, operator precedence grammar, simple math, solving linear equations, constant folding.
534 - Frogger - graph theory, shortests paths, SSSP, Bellman-Ford (different distance notion).
535 - Globetrotter - geometry, great circle distances.
536 - Tree Recovery - trees, tree traversal, reconstructing tree from preorder and inorder.
537 - Artificial Intelligence - ad hoc, string manipulation.
539 - The Settlers of Catan - graph theory, longest path, NP-complete, backtracking, brute force.
541 - Error Correction - ad hoc.
542 - France 98 - probability theory, conditional probabilities, math.
543 - Goldbach's Conjecture - number theory, sieve, primes, searching.
544 - Heavy Cargo - graph theory, MST (maximum spanning tree).
547 - DDF - ad hoc, simulation, math, number theory, divisors.
555 - Bridge Hands - ad hoc, sorting.
558 - Wormholes - graph theory, negative weight cycle, Bellman-Ford.
562 - Dividing Coins - DP, 0-1 knapsack, subset sum.
563 - Crimewave - graph theory, max-flow.
565 - Pizza Anyone? - SAT, satisfiability, NP-complete, backtracking.
567 - Risk - graph theory, BFS.
568 - Just the Facts - ad hoc, number theory, factorials (or bignum).
571 - Jugs - number theory, relative primality, the sequence iA mod B for i=0..B-1 (or graph traversal, eg. BFS).
572 - Oil Deposits - graph theory, BFS, flood fill.
573 - The Snail - ad hoc, simulation, math.
574 - Sum It Up - subset sum, brute force, backtracking.
575 - Skew Binary - ad hoc.
576 - Haiku Review - ad hoc.
579 - ClockHands - ad hoc.
580 - Critical Mass - number theory, recurrences.
583 - Prime Factors - number theory, sieve, primes, trial division, prime factorization.
585 - Triangles - ad hoc.
587 - There's Treasure Everywhere - ad hoc.
590 - Always on the Run - DP.
591 - Box of Bricks - ad hoc.
594 - One Little, Two Little, Three Little Endians - ad hoc, bitmasking, and/or etc.
600 - A Duckpin Tournament - ad hoc, simulation, duckpin bowling.
601 - The Path - graph theory, shortest paths, BFS.
602 - What Day Is It? - ad hoc, math, modulo, simulation.
603 - Parking Lot - ad hoc, simulation.
604 - The Boggle Game - backtracking.
607 - Scheduling Lectures - DP.
608 - Counterfeit Dollar - ad hoc.
610 - Street Directions - graph theory, bridge, biconnected components, DFS.
612 - DNA Sorting - ad hoc, sorting, inversion counting (insertion sort).
613 - Numbers that Count - ad hoc, simulation.
615 - Is It A Tree - graph theory, trees, connectivity.
616 - Coconuts, Revisited - math, number theory, divisors, monkey and coconut problem.
619 - Numerically Speaking - ad hoc, lexicographic order, bignum.
620 - Cellular Structure - DP, parsing.
621 - Secret Research - ad hoc.
623 - 500! - bignum.
624 - CD - DP, 0/1 knapsack, subset sum, or brute force.
628 - Passwords - ad hoc, recursion.
634 - Polygon - computational geometry, point in polygon.
636 - Squares - number theory, ad hoc, base conversion.
637 - Booklet Printing - ad hoc.
639 - Don't Get Rooked - backtracking, brute force.
640 - Self Numbers - ad hoc.
641 - Do the Untwist - ad hoc.
642 - Word Amalgamation - ad hoc, sorting, multimaps.
644 - Immediate Decodability - ad hoc, string matching.
656 - Optimal Programs - exhaustive search, graph theory, IDDFS (iterative deepening DFS).
657 - The Die is Cast - graph theory, flood fill, DFS.
661 - Blowing Fuses - ad hoc, simulation.
663 - Sorting Slides - graph theory, maximum cardinality bipartite matching.
670 - The Dog Task - graph theory, maximum cardinality bipartite matching.
673 - Parentheses Balance - ad hoc, stacks.
674 - Coin Change - DP, coin change.
679 - Dropping Balls - ad hoc, trees, binary representation.
681 - Convex Hull Finding - computational geometry, convex hull.
684 - Integral Determinant - Gaussian elimination, matrices, determinants.
686 - Goldbach's Conjecture (II) - number theory, sieve, primes, searching.
694 - The Collatz Sequence - ad hoc, simulation (like UVA 100).
696 - How Many Knights - math, closed solution.
699 - The Falling Leaves - trees, preorder traversal.
700 - Date Bugs - ad hoc.
701 - Archaelogist's Dilemma - math, brute force.
702 - The Vindictive Coach - DP.
703 - Triple Ties: The Organizer's Nightmare - ad hoc, brute force.
705 - Slash Maze - graphs, DFS, traversal, flood fill.
706 - LC-Display - ad hoc.
707 - Robbery - graph theory, graph traversal, DFS.
709 - Formatting Text - DP, printing the solution.
711 - Dividing up - DP.
712 - S-Trees - trees, tree traversal.
713 - Adding Reversed Numbers - ad hoc, simple math, bignum addition.
714 - Copying Books - binary search, greedy (or DP).
715 - Substitution Cipher - graph theory, DAG, topological sorting, linear ordering, Floyd-Warshall, transitive closure, strings, lexicographic comparision, cryptography, substitution cipher, sorting.
716 - Commedia dell Arte - math, abstract algebra, 15 puzzle, generalized 15 puzzle, 15 puzzle in 3D, permutations, sign of a permutation, manhattan metric, invariants, induction.
718 - Skyscraper Floors - graph theory, DFS, reachability, math, modular congruences, linear diophantine equations, extended gcd, Bezout's identity.
719 - Glass Beads - strings, minimum lexicographic rotation.
721 - Invitation Cards - graph theory, shortest paths, Dijkstra, SSSP.
725 - Division - ad hoc, division, brute force.
727 - Equation - parsing, infix to postfix.
729 - Hamming Distance Problem - brute force, backtracking.
737 - Gleaming the Cubes - computational geometry, intersection of cubes.
739 - Soundex Indexing - ad hoc.
740 - Baudot Data Communication Code - ad hoc.
741 - Burrows Wheeler Decoder - string algorithms, data compression, BWT, Burrows Wheeler Transform, inverse BWT, block-sorting compression.
748 - Exponentiation - bignum.
750 - 8 Queens Chess Problem - backtracking, 8-queens problem.
753 - A Plug for Unix - graph theory, max-flow.
755 - 487-3279 - ad hoc, sorting.
756 - Biorhythms - math, modular arithmetic, Chinese Remainder Theorem, CRT, Euclid's extended algorithm.
762 - We Ship Cheap - graph theory, BFS, shortest paths, printing the path.
763 - Fibinary Numbers - ad hoc, math, Fibonacci numbers, Zeckendorf representation, addition of numbers in Zeckendorf representation, (or Bignum, greedy).
784 - Maze Exploration - graph theory, graph traversal, flood fill.
787 - Maximum Sub-sequence Product - bignum, DP, simple math.
793 - Network Connections - partially dynamic connected components, union-find.
796 - Critical Links - graph theory, bridge (biconnected components).
802 - Lead or Gold - linear programming, one-phase simplex method.
820 - Internet Bandwidth - graph theory, max-flow.
821 - Page Hopping - graph theory, all-pairs shortest paths, APSP, Floyd-Warshall (or BFS).
825 - Walking on the Safe Side - graph theory, DAG, counting paths in a DAG, DP.
834 - Continued Fractions - ad hoc.
836 - Largest Submatrix - maximum 2D sum (special case, reduction, see UVA 108), DP.
839 - Not so Mobile - ad hoc, simulation, simple math, recursion.
843 - Crypt Kicker - backtracking, sorting.
846 - Steps - ad hoc, math.
847 - A multiplication game - ad hoc, game theory, number theory.
848 - FMT - greedy, ad hoc.
850 - Crypt Kicker II - ad hoc.
861 - Little Bishops - backtracking, combinatorics, product rule.
866 - Intersecting Line Segments - computational geometry, line segment intersection.
872 - Ordering - graph theory, topological sort, backtracking (like UVA 124).
880 - Cantor Fractions - math, binary search (or closed form solution), (like UVA 264).
882 - The Mailbox Manufacturers Problem - DP.
884 - Factorial Factors - number theory, sieve (modified), primes.
895 - Word Problem - ad hoc.
900 - Brick Wall Patterns - number theory, recurrences, Fibonacci numbers.
902 - Password Search - strings, maximum repeated substring of a fixed length, hashing.
903 - Spiral of Numbers - ad hoc, coordinate systems, simple math, (or fast simulation), (see also UVA 10920).
904 - Overlapping Air Traffic Control - computational geometry, volume of union of 3D boxes, intersection of 3D boxes, coordinate compression.
905 - Tacos Panchita - ad hoc, simple math, geometry.
906 - Rational Neighbor - ad hoc, simple math, fractions, linear search.
907 - Winterim Backpacking Trip - DP, (or binary search, greedy).
908 - Re-connecting Computer Sites - graph theory, MST.
909 - The BitPack Data Compression Problem - DP, printing the solution.
910 - TV game - DP, graph theory.
911 - Multinomial Coefficients - math, multinomial coefficients.
912 - Live From Mars - ad hoc, string manipulation, data structures, union-find, graph theory.
913 - Joanna and the Odd Numbers - number theory, odd numbers, summations.
914 - Jumping Champion - number theory, sieve, primes, linear search.
918 - ASCII Mandelbrot - ad hoc, simulation, math, complex numbers, Mandelbrot set.
920 - Sunny Mountains - computational geometry, sweep line, line and line intersection, sorting.
922 - Rectangle by the Ocean - geometry, area of polygon, rectangles.
924 - Spreading the News - graph theory, shortest paths, BFS.
925 - No more prerequisites, please! - graph theory, DAG, topological sorting, identifying direct dependencies, transitive closure, Floyd-Warshall.
926 - Walking Around Wisely - DP, graph theory, DAG, counting paths in a DAG.
927 - Integer Sequences from Addition of Terms - ad hoc, simple math, sum of first n integers, evaluating polynomials, quadratic equations (or binary search).
928 - Eternal Truths - graph theory, BFS, shortest paths.
929 - Number Maze - graph theory, shortest paths, Dijkstra (on a sparse graph), array priority queue, see CLRS exercise 24.3-6.
944 - Happy Numbers - simple math, happy numbers, DP, brute force, cycle detection.
948 - Fibonaccimal Base - ad hoc, math, Fibonacci numbers, Zeckendorf representation, greedy.
957 - Popes - ad hoc.
962 - Taxicab Numbers - simple math, brute force, (or precalculation).
967 - Circular - number theory, sieve, primes, prefix sums.
972 - Horizon Line - ad hoc, geometry, sweep line algorithm, computing the upper envelope.
974 - Kaprekar Numbers - number theory.
985 - Round And Round Maze - graph theory, shortest paths, BFS.
986 - How Many? - DP, math, combinatorics.
988 - Many paths, one destination - graph theory, DAG, counting number of paths in a DAG, DP.
989 - Su Doku - sudoku, logic puzzles, backtracking, NP-complete, brute force.
990 - Diving For Gold - DP, knapsack, printing the solution.
991 - Safe Salutations - DP, Catalan numbers, number theory.
993 - Product of digits - simple math, greedy, prime factorization, (see also SRM 424 Div 1 250).
995 - Super Divisible Numbers - ad hoc, recursion, simple math, divisibility, modulo.
997 - Show the Sequence - ad hoc, simple math, parsing.
10000 - Longest Paths - graph theory, DAG, longest path (similar to DAG shortest paths).
10001 - Garden of Eden - backtracking.
10002 - Center Of Masses - computational geometry, convex hull, centroids.
10003 - Cutting Sticks - DP, memoization.
10004 - Bicoloring - graph theory, DFS, bipartite graphs, 2-colorability.
10005 - Packing Polygons - computational geometry, brute force, circle through 2 points, point in circle.
10006 - Carmichael Numbers - number theory, math, primes, pseudoprimes.
10007 - Count the Trees - bignum, Catalan numbers, binary trees.
10008 - What's Cryptanalysis? - ad hoc, sorting.
10009 - All Roads Lead Where? - graph theory, BFS, shortest paths.
10010 - Where's Waldorf - ad hoc, string matching.
10012 - How Big Is It - geometry, brute force, backtracking.
10013 - Super long sums - bignum, addition.
10014 - Simple Calculations - recurrences, ad hoc.
10015 - Joseph's Cousin - ad hoc, simulation, Josephus problem, number theory, primes, sieve.
10017 - The Never Ending Towers of Hanoi - ad hoc, simulation, towers of hanoi, the recursive algorithm.
10018 - Reverse and Add - ad hoc.
10019 - Funny Encryption Method - ad hoc.
10020 - Minimal Coverage - greedy.
10023 - Square Root - bignum, integer square root, divide and conquer (google for Modern Computer Arithmetic).
10024 - Curling up the cube - ad hoc, graph theory, DFS, "rolling the die", (see TopCoder SRM 417 Div 1 500, CubeNets).
10025 - The ?1?2?3?...?n = k problem - number theory, triangular numbers.
10026 - Shoemaker's problem - greedy, sorting.
10029 - Edit Step Ladders - graph theory, DAG, longest paths, hashing, DP.
10032 - Tug of War - DP, memoization, pruning, subset sum, knapsack.
10033 - Interpreter - ad hoc, simulation.
10034 - Freckles - graph theory, MST (or Euclidean MST).
10035 - Primary Arithmetic - ad hoc, addition.
10036 - Divisibility - DP, subset sum, number theory, NP-hard, pseudopolynomial.
10037 - Bridge - ad hoc, puzzles, river crossing problem, bridge and torch problem.
10038 - Jolly Jumpers - ad hoc.
10039 - Railroads - graph theory, DFS, reachability.
10040 - Ouroboros Snake - graph theory, Euler tour, De Bruijn sequences (or backtracking, brute force).
10041 - Vito's family - sorting, median selection.
10042 - Smith numbers - number theory, sieve, primes.
10043 - Chainsaw Massacre - computational geometry, sweep line, maximum area empty rectangle.
10044 - Erdos numbers - graph theory, BFS.
10045 - Echo - ad hoc.
10047 - The Monocycle - graph theory, BFS.
10048 - Audiophobia - graph theory, MST.
10049 - Self-describing sequence - ad hoc, number theory, searching.
10050 - Hartals - ad hoc, simulation, sorting.
10051 - Tower of Cubes - DP, graph theory, DAG, longest path.
10054 - The Necklace - graph theory, Euler tour, connectivity.
10055 - Hashmat The Brave Warrior - ad hoc.
10056 - What is the Probability? - probability theory, infinite geometric series.
10057 - A mid-summer night's dream - ad hoc, simple math, "prefix sums".
10061 - How Many Zeros and How Many Digits? - math, number theory, primes, sieve, divisibility, logarithms.
10062 - Tell Me The Frequencies - ad hoc, sorting.
10063 - Knuth's Permutation - ad hoc, generating permutations.
10065 - Useless Tile Packers - computational geometry, convex hull, area of polygons.
10066 - The Twin Towers - DP, LCS.
10067 - Playing with Wheels - graph theory, BFS.
10069 - Distinct Subsequences - DP.
10070 - Leap Year or Not Leap Year and ... - ad hoc, bignum, modular arithmetic.
10071 - Back To High School Physics - ad hoc, physics.
10072 - Bob Laptop Woolmer and Eddie Desktop Barlow - maximum cost weighted maximum cardinality bipartite matching, Kuhn-Munkres (Hungarian) algorithm, max-cost max-flow.
10074 - Take the Land - maximum 2D sum (like UVA 108), DP.
10075 - Airlines - graph theory, APSP, all-pairs shortest paths, Floyd-Warshall, geometry, great-circle distances.
10077 - Stern-Brocot - number theory, binary search.
10078 - The Art Gallery - computational geometry, convex hull, testing if a polygon is convex.
10079 - Pizza Cutting - math, recurrences.
10080 - Gopher II - graph theory, maximum cardinality bipartite matching.
10081 - Tight words - DP.
10082 - WERTYU - ad hoc.
10083 - Division - bignum, math.
10084 - Hotter Colder - computational geometry, cutting polygons by a straight line.
10085 - The Most Distant State - graph theory, BFS, shortest paths, 8-puzzle, permutation encoding, hashmap.
10088 - Trees on My Island - computational geometry, gcd, Pick's theorem, area computation.
10089 - Repackaging - linear algebra, vectors, angles.
10090 - Marbles - number theory, extended Euclidean algorithm, gcd.
10092 - The Problem with the Problemsetter - graph theory, maximum cardinality bipartite matching.
10093 - An Easy Problem - number theory, number base conversion, modulo.
10094 - Place The Guards - ad hoc, case analysis, even/odd numbers, spotting the pattern, (or backtracking, pruning).
10097 - The Color Game - graph theory, shortest paths, BFS.
10098 - Generating Fast Sorted Permutations - ad hoc, sorting, recursion (like UVA 195).
10099 - Tourist Guide - graph theory, SSSP, shortest paths, Bellman-Ford (different relaxation operation).
10100 - Longest Match - DP, LCS (on words), parsing.
10101 - Bangla Numbers - ad hoc.
10102 - The Path in the Colored Field - graph theory, BFS, shortest paths.
10103 - Karpovich Blocks - graph theory, DFS.
10104 - Euclid Problem - number theory, extended euclidean algorithm, gcd.
10105 - Polynomial coefficient - number theory, binomial coefficients.
10106 - Product - bignum, simple math, multiplication.
10107 - What is the Median - sorting, median selection, dynamic algorithm.
10108 - The Mosquito Killer Mosquitos - bignum, square roots.
10109 - Solving Systems of Linear Equations - systems of linear equations, Gaussian elimination, exact rational arithmetic.
10110 - Light, more light - number theory, math, divisors, prime factorization, perfect squares.
10111 - Find the Winning Move - DP, tic-tac-toe, game tree evaluation.
10112 - Myacm Triangles - geometry, brute force, point in triangle, triangle area.
10113 - Exchange Rates - graph theory, DFS, gcd.
10114 - Loansome Car Buyer - ad hoc, simulation.
10115 - Automatic Editing - string manipulation, ad hoc.
10116 - Robot Motion - ad hoc, simulation.
10117 - Nice Milk - computational geometry, cutting polygons by lines, brute force, vectors.
10118 - Free Candies - DP.
10120 - Gift?! - math, simulation.
10122 - Mysterious Mountain - graph theory, maximum cardinality bipartite matching, binary search (bisection).
10123 - No Tipping - geometry, physics, backtracking, brute force.
10125 - Sumsets - brute force, sorting.
10126 - Zipf's Law - ad hoc, string manipulation.
10127 - Ones - number theory, modular arithmetic.
10128 - Queue - DP, permutations, recurrences.
10129 - Play on Words - graph theory, Euler tour, connectivity, union-find (or DFS).
10130 - SuperSale - DP, knapsack.
10131 - Is Bigger Smarter? - DP, LIS, LCS, sorting (or graph theory, DAG, longest path).
10132 - File Fragmentation - sorting, ad hoc.
10133 - Audubon's Stormy Artic Trip - graph theory, DAG, traversal.
10134 - Autofish - ad hoc, simulation.
10135 - Herding Frosh - computational geometry, convex hull, brute force, sorting.
10136 - Chocolate Chip Cookies - geometry, circles, circle through 2 points, point in circle.
10137 - The Trip - ad hoc.
10138 - CDVII - ad hoc, simulation, sorting.
10139 - Factovisors - number theory.
10140 - Prime Distances - number theory, primality testing, sieve, segmented sieve.
10141 - Request for Proposal - ad hoc.
10142 - Australian Voting - ad hoc, simulation.
10144 - Expression - math, Boolean logic, NAND gates, binary addition.
10145 - Lock Manager - ad hoc, simulation.
10146 - Dictionary - ad hoc, string manipulation.
10147 - Highways - graph theory, MST.
10148 - Advertisement - greedy, sorting.
10149 - Yahtzee - DP, bitmasks.
10150 - Doublets - backtracking, sorting.
10151 - Spaghetti - graph theory, graph traversal, DFS, DP, program equivalence, control flow graph, dataflow analysis, string manipulation, loop unrolling, cycle detection.
10152 - Shellsort - ad hoc, stacks.
10154 - Weights and Measures - DP, sorting, LIS (modified).
10156 - Sala-ma-Sond, A Nice Little Pond - ad hoc, simulation, pretty printing
10157 - Expressions - DP, recurrences, Catalan numbers, bignum.
10158 - War - data structures, augmenting data structures, union-find, equivalence relations (see also 10505).
10159 - Star - DP, geometry, triangular grids.
10160 - Servicing Stations - backtracking, graph theory, dominating set, NP-complete.
10161 - Ant on a Chessboard - ad hoc, math.
10162 - Last Digit - cycle finding, number theory, modulo, bignum.
10163 - Storage Keepers - DP, binary search.
10164 - Number Game - math.
10165 - Stone Game - combinatorial game theory, nim.
10166 - Travel - graph theory, shortest paths, SSSP, DAG shortest paths, DP.
10167 - Birthday Cake - computational geometry, brute force.
10168 - Summation of 4 primes - math, number theory, sieve, primes.
10169 - Urn-ball probabilities - DP, probability theory.
10170 - The Hotel with Infinte Rooms - number theory, quadratic equation.
10171 - Meeting Prof. Miguel - graph theory, shortest paths, Floyd-Warshall.
10172 - The Lonesome Cargo Distributor - ad hoc, simulation.
10173 - Smallest Bounding Rectangle - computational geometry, minimum area enclosing rectangle, convex hull, binary search, rotations, extreme point in a given direction (or rotating calipers).
10174 - Couple-Bachelor-Spinster Numbers - number theory, math, case analysis (modulo 4).
10176 - Ocean Deep! Make it shallow! - number theory, divisibility, modulo.
10177 - (2/3/4)-D Sqr/Rects/Cubes/Boxes? - simple math, summations, sums of i^th powers of the first n integers.
10178 - Count the Faces - graph theory, Euler's formula, connectivity, connected components, graph traversal, DFS.
10179 - Irreducible Basic Fractions - math, number theory, totient function, prime factorization.
10180 - Rope Crisis In Ropeland - geometry, closest point on line segment, circles, tangents, angles.
10181 - 15 Puzzle Problem - 15 puzzle, graph theory, IDDFS (iterative deepening DFS), heuristics, math, abstract algebra, determining if there is no solution.
10182 - Bee Maja - ad hoc, simulation, coordinate systems, hexagonal grid.
10183 - How many Fibs? - bignum, math, Fibonacci numbers.
10185 - Phylogenetic Trees Inherited - strings, trees, complete binary tree, greedy, (or DP).
10186 - Euro Cup 2000 - ad hoc, backtracking, brute force.
10187 - From Dusk till Dawn - graph theory, BFS, shortest paths.
10188 - Automated Judge Script - ad hoc, simulation.
10189 - Mine Sweeper - ad hoc.
10190 - Divide but not quite Conquer - ad hoc, simulation, recursion.
10191 - Longest Nap - ad hoc.
10192 - Vacation - DP, LCS (Longest Common Subsequence).
10193 - All You Need Is Love - number theory, gcd.
10194 - Football - ad hoc, sorting.
10195 - Knights of the round table - geometry, Heron's formula, radius of triangle incircle.
10196 - Check The Check - ad hoc, simulation.
10197 - Learning Portuguese - ad hoc, string manipulation.
10198 - Counting - bignum, recurrences.
10199 - Tourist Guide - graph theory, connectivity, DFS, articulation points.
10200 - Prime Time - number theory, prefix sum.
10201 - Adventures in Moving - Part IV - DP.
10202 - Pairsumonious Numbers - number theory, math, sorting.
10203 - Snow Clearing - graph theory, Euler tour.
10205 - Stack 'em Up - ad hoc.
10207 - The Unreal Tournament - DP, bignum, math, binomial coefficients.
10209 - Is this Integration - geometry.
10212 - The Last Non-zero Digit - number theory, modulo.
10213 - How many pieces of land - bignum, Moser's circle problem, recurrences, combinatorics, binomial coefficients.
10215 - Largest-Smallest Box - geometry, quadratic equation, calculus.
10219 - Find the Ways! - number theory, combinatorics.
10220 - I Love Big Numbers! - simple math, bignum, factorials.
10221 - Satellites - geometry, circles, triangles, cosine relation.
10222 - Decode The Mad Man - ad hoc.
10223 - How Many Nodes? - number theory, Catalan numbers, binary trees.
10225 - Discrete Logging - math, discrete logarithm, baby-step giant-step algorithm.
10226 - Hardwood Species - ad hoc, data structures, trie.
10227 - Forests - ad hoc.
10229 - Modular Fibonacci - number theory, modular arithmetic, matrices, repeated squaring, Fibonacci numbers.
10235 - Simply Emirp - number theory, sieve, primes.
10236 - The Fibonacci Primes - number theory, math, gcd, Fibonacci numbers.
10242 - Fourth Point!!! - geometry, ad hoc.
10243 - Fire! Fire!! Fire!!! - graph theory, minimum vertex cover in a tree.
10245 - The Closest Pair Problem - computational geometry, closest pair problem, sorting, divide and conquer.
10246 - Asterix and Obelix - graph theory, all-pairs shortest paths, APSP, Floyd-Warshall, sorting.
10247 - Complete Tree Labeling! - DP, recurrences, binomial coefficients, permutations, bignum.
10249 - The Grand Dinner - greedy method (or graph theory, max-flow).
10252 - Common Permutation - ad hoc.
10254 - The Priest Mathematician - math, bignum, recurrences, Hanoi towers with four pegs.
10258 - Contestant scoreboard - ad hoc.
10259 - Hippity Hopscotch - graph theory, DAG, longest path, DP (or topological sorting).
10260 - Soundex - ad hoc.
10261 - Ferry Loading - DP, number split, subset sum, knapsack, pseudopolynomial.
10263 - Railway - computational geometry, closest point on line segment.
10267 - Graphical Editor - ad hoc, simulation.
10268 - 498 - ad hoc, evaluating a polynomial, derivates, simple math.
10269 - Adventure of Super Mario - graph theory, shortest paths, SSSP, Dijkstra (on a modified graph).
10271 - Chopsticks - DP, sorting.
10273 - Eat or not to Eat? - data structures, priority queue, simulation, simple math, gcd, lcm, periodicity.
10275 - Guess The Number - math, logarithms, fingerprinting (or hashing), (Bignum).
10276 - Hanoi Tower Troubles Again - graph theory, DFS, backtracking.
10277 - Boastin' Red Socks - probability theory, searching.
10278 - Fire Station - graph theory, shortest paths, Dijkstra, multiple souces.
10279 - Minesweeper - ad hoc, simulation.
10280 - Old Wine Into New Bottles - DP, graph theory, Dijkstra.
10281 - Average Speed - ad hoc.
10282 - Babelfish - ad hoc, hashing, dictionary problem.
10285 - Longest Run on a Snowboard - DP.
10286 - The Trouble with a Pentagon - geometry, sine theorem, angles.
10293 - Word Length and Frequency - ad hoc, strings.
10295 - Hay Points - ad hoc.
10296 - Jogging Trails - graph theory, Chinese postman problem, all-pairs shortest paths, Floyd-Warshall, minimum cost maximum matching in general graphs, DP.
10297 - Beavergnaw - geometry, cones, cylinders, volumes.
10298 - Power Strings - ad hoc, string matching, string period.
10299 - Relatives - math, number theory, totient, divisors, primes, (see also UVA 11064).
10300 - Ecological Premium - ad hoc.
10301 - Rings and Glue - computational geometry, circle & circle intersection, disjoint sets, union-find, graph theory, connected components.
10302 - Summation of Polynomials - bignum, sums.
10303 - How Many Trees - bignum, combinatorics, recurrences, Catalan numbers.
10304 - Optimal Binary Search Tree - DP.
10305 - Ordering Tasks - graph theory, topological sort.
10306 - e-Coins - DP, coin change (a bit modified).
10307 - Killing Aliens in Borg Maze - graph theory, MST, shortests paths, BFS.
10308 - Roads in the North - graph theory, diameter of an unrooted tree, BFS.
10309 - Turn the Lights Off - ad hoc, brute force (or math, linear algebra, solving linear equation systems).
10310 - Dog and gopher - geometry, brute force.
10311 - Goldbach and Euler - number theory, sieve, primes, searching, trial division.
10312 - Expression Bracketing - combinatorics, number theory, Catalan numbers, super Catalan numbers, number of binary bracketings, number of bracketings.
10313 - Pay the Price - DP, coin change, prefix sums.
10315 - Poker Hands - ad hoc, ranking poker hands.
10316 - Airline Hub - geometry, great circle distances, brute force.
10319 - Manhattan - 2-SAT, graph theory, reachability, strongly connected components.
10321 - Polygon Intersection - computational geometry, intersection of convex polygons, cutting polygons by a straight line.
10323 - Factorial! You Must Be Kidding - number theory, factorials.
10324 - Zeros and Ones - ad hoc, prefix sums.
10325 - The Lottery - number theory, divisibility, gcd, lcm, inclusion-exclusion.
10327 - Flip Sort - sorting, counting inversions.
10328 - Coin Toss - bignum, combinatorics, recurrences.
10329 - Combinatorial Expression - bignum, number theory, sieve, primes, prime factorization.
10330 - Power Transmission - graph theory, max-flow, vertex constraints.
10334 - Ray Through Glasses - bignum, Fibonacci numbers.
10336 - Rank the Languages - graph theory, graph traversal, DFS, flood fill.
10338 - Mischievous Children - math, multinomial coefficients.
10340 - All in All - greedy (or DP, LCS).
10341 - Solve It - math, bisection, root finding, numerical analysis.
10342 - Always Late - graph theory, K shortest paths (K=2), Bellman-Ford (modified), Dijkstra (modified).
10344 - 23 Out of 5 - backtracking, brute force.
10346 - Peter's Smokes - ad hoc.
10347 - Medians - geometry, triangle area from medians.
10348 - Submarines - computational geometry, line and line segment intersection, point in polygon, line segment in polygon.
10349 - Antenna Placement - graph theory, maximum cardinality bipartite matching.
10350 - Liftless Eme - graph theory, shortest paths, SSSP, DAG shortest paths.
10351 - Diamond - geometry, math, ellipsoid, ellipse.
10355 - Superman - geometry, vector equation of a line, cartesian equation of sphere, quadratic equations.
10358 - Matrix - game trees (graphs), solving game trees (graphs), DP, memoization, simple recursive games, retrograde analysis.
10359 - Tiling - math, recurrences, big num.
10361 - Automatic Poetry - ad hoc, string manipulation.
10363 - Tic Tac Toe - ad hoc, 3 x 3 tic tac toe, board games, evaluating board positions.
10365 - Blocks - ad hoc, number theory, divisors.
10367 - Equations - equations, gcd, fractions (many, many special cases).
10368 - Euclid's Game - ad hoc, gcd.
10369 - Arctic Networks - graph theory, MST, Kruskal's algorithm, union-find (or binary search).
10370 - Above Average - ad hoc.
10374 - Election - ad hoc.
10375 - Choose and Divide - ad hoc, math, binomial coefficients.
10377 - Maze Traversal - ad hoc, simulation.
10378 - Complex Numbers - math, complex numbers, De Moivre's theorem.
10380 - Shogi Tournament - graph theory, max-flow, searching (linear/binary search).
10382 - Watering Grass - computational geometry, greedy, interval covering, sorting.
10385 - Duathlon - numerical analysis, ternary search.
10387 - Billiard - geometry, math, trigonometry.
10391 - Compound Words - hashing, hash tables, strings.
10392 - Factoring Large Numbers - number theory, math, primes, sieve, factorization.
10394 - Twin Primes - number theory, primes, sieve.
10397 - Connect the Campus - graph theory, MST.
10400 - Game Show Math - DP.
10401 - Injured Queen Problem - DP.
10404 - Bachet's Game - DP, games, winning/losing positions.
10405 - Longest Common Subsequence - DP, LCS.
10406 - Cutting Tabletops - computational geometry, convex polygons, line-line intersection, area of a polygon, vectors.
10407 - Simple Division - number theory, remainders, gcd.
10408 - Farey Sequences - number theory, gcd, fractions, sorting.
10409 - Die Game - ad hoc.
10410 - Tree Reconstruction - graph theory, trees, reconstructing tree from DFS and BFS traversal.
10415 - Eb Alto Saxophone Player - ad hoc, simulation.
10420 - List of Conquests - ad hoc, sorting
10422 - Knights in Fen - graph theory, BFS, hashing.
10424 - Love Calculator - ad hoc.
10427 - Naughty Sleepy Boys - ad hoc.
10432 - Polygon Inside a Circle - geometry, area of a regular convex polygon.
10440 - Ferry Loading II - greedy.
10443 - Rock, Scissors, Paper - ad hoc, simulation.
10450 - World Cup Noise - math, bignum, number theory, recurrences.
10451 - Ancient Village Sports - geometry.
10452 - Marcus Help! - graph theory, graph traversal, DFS.
10453 - Make Palindrome - DP, printing solution, strings, palindromes.
10459 - The Tree Root - graph theory, diameter of an unrooted tree, center of an unrooted tree, DFS.
10465 - Homer Simpson - DP.
10469 - To Carry or not to Carry - ad hoc, xor.
10473 - Simple Base Conversion - ad hoc, number base conversion (or printf).
10474 - Where is the Marble? - ad hoc, counting sort, bucket array.
10482 - The Candyman Can - DP, sorting, subset sum.
10487 - Closests Sums - ad hoc, brute force.
10489 - Boxes of Chocolates - ad hoc, number theory, modulo.
10490 - Mr. Azad and His Son - number theory, perfect numbers, divisors, primality testing.
10491 - Cows and Cars - probability theory, conditional probabilities, Monty Hall problem (generalized).
10493 - Cats, with or without Hats - ad hoc, simple math, number of internal nodes and leaves in a tree with degree n.
10494 - If We Were a Child Again - bignum, division.
10496 - Collecting Beepers - graph theory, TSP, DP (or brute force).
10498 - Happiness - linear programming, one-phase simplex method.
10499 - The Land of Justice - ad hoc, math.
10500 - Robot Maps - ad hoc, simulation, pretty-printing.
10502 - Counting Rectangles - ad hoc.
10505 - Montesco vs Capuleto - data structures, augmenting data structures, union-find, equivalence relations (see also 10158).
10508 - Word Morphing - backtracking, brute force, string matching.
10509 - R U Kidding Mr. Feynman - ad hoc, numerical approximation.
10510 - Cactus - graph theory, strongly connected components, directed cactus graph, determining if a graph is a directed cactus, graph traversal, DFS, DFS edge classification, back edges.
10511 - Councilling - graph theory, max-flow, vertex constraints.
10515 - Power et al - cycle finding.
10518 - How Many Calls? - recurrence relations, fibonacci numbers using repeated squaring, modulo (or cycle finding, Floyd's Cycle Finding Algorithm).
10519 - Really Strange - bignum, recurrences.
10523 - Very Easy!!! - bignum, number theory, exponentiation.
10527 - Persistent Numbers - simple math, greedy, bignum, prime factorization, (see also UVA 993, see also SRM 424 Div 1 250).
10530 - Guessing Game - ad hoc, simulation.
10533 - Digit Primes - number theory, sieve.
10534 - Wavio Sequence - DP, LIS (in O(nlogn), binary search).
10539 - Almost Prime Numbers - number theory, divisibility, prime numbers, sieve, binary search.
10549 - Russian Dolls - DP, printing solution.
10550 - Combination Lock - ad hoc.
10551 - Basic Remains - number theory, math, modulo, number base conversion.
10553 - Treasure Map - computational geometry, angles, distance from point to line segment.
10554 - Calories From Fat - ad hoc.
10557 - XYZZY - graph theory, Bellman-Ford, negative (positive) cycles, reachability.
10558 - A Brief Gerrymander - DP, printing the solution.
10559 - Blocks - DP.
10564 - Paths Through The Hourglass - DP, printing solution.
10570 - Meeting with Aliens - ad hoc, minimum number of swaps, sorting, permutations, greedy.
10573 - Geometry Paradox - geometry.
10579 - Fibonacci Numbers - bignum, recurrences, Fibonacci numbers.
10583 - Ubiquitous Religions - graph theory, union-find.
10586 - Polynomial Remains - polynomials, long division, math.
10589 - Area - ad hoc, geometry, point in circle.
10591 - Happy Number - simple math, happy numbers, cycle finding (Floyd's cycle finding algorithm).
10593 - Kites - DP.
10594 - Data Flow - graph theory, min-cost max-flow.
10596 - Morning Walk - graph theory, Euler tour, DFS, connectivity.
10599 - Robots (II) - DP.
10600 - ACM Contest and Blackout - graph theory, MST, second-best MST.
10601 - Cubes - math, number of edge colorings of a cube under rotations, Burnside's lemma, orbits, abstract algebra, group theory, combinatorics, cubes, rotations, factorials, multinomial coefficients.
10602 - Editor Nottobad - greedy.
10603 - Fill - graph theory, shortest paths, SSSP, Dijkstra, DP.
10604 - Chemical Reaction - DP.
10605 - Mines for Diamonds - DP, all subsets, bitmasks, graph theory, path cover, geometry, manhattan distance, (similar to TSP).
10606 - Opening Doors - math, perfect squares, divisors, bignum, integer square root (or binary search).
10607 - Siege - graph theory, connected components, shortest paths, BFS.
10608 - Friends - graph theory, union-find.
10610 - Gopher and Hakws - graph theory, BFS, shortest paths, SSSP.
10611 - The Playboy Chimp - ad hoc.
10613 - Mushroom Misery - computational geometry, circles, 2D grid, counting number of grid squares inside the circles, distance from point to line segment, divide and conquer, (or sweepline algorithm).
10614 - Dreadful Vectors - parsing, recursive descent parsing, LL(1), context-free grammars, operator precedence, operator associativity, abstract syntax tree, AST, type checking, tree traversal, simple math, vectors, scalars, cross product, dot product.
10615 - Rooks - graph theory, minimum edge coloring of a bipartite graph, Hall's marriage theorem, maximum-cardinality bipartite matching, d-regular bipartite multigraph.
10616 - Divisible Group Sums - DP, math, modulo.
10617 - Again Palindromes - DP.
10618 - Tango Tango Insurrection - DP, printing the solution, Dance Dance Revolution.
10619 - Advanced Causal Measurements - binary search, interval covering, greedy, exponential search.
10622 - Perfect Pth Powers - math, number theory, prime factorization, gcd.
10623 - Thinking Backward - combinatorial geometry, arrangements, math, plane division by circles, triangles, ellipses, maximum number of regions, multivariate equations, quadratic equation in one variable.
10624 - Super Number - math, divisibility, backtracking, precalculation.
10625 - GNU = GNU'sNotUnix - math, linear recurrences, linear algebra, linear transformations, repeated squaring on a matrix, (or DP).
10626 - Buying Coke - DP.
10627 - Infinite Race - math, gcd, fractions.
10633 - Rare Easy Problem - ad hoc, number theory, modulo, floor.
10634 - Say NO To Memorization - math, number of terms in equation with degree n and v variables, combinatorics, binomial coefficients, combinations with repetitions, number of non-negative integer solutions of x0 + x1 + ... + x_m = k.
10635 - Prince and Princess - DP, LIS in O(nlogn), reduction from special case of LCS to LIS.
10637 - Coprimes - backtracking, pruning, sorting, math, number theory, partitions, coprimes, gcd.
10642 - Can You Solve It? - ad hoc, counting, simple math.
10643 - Facing Problem With Trees - DP, bignum, trees, number of ordered binary trees with m edges.
10644 - Floor Tiles - geometry, tiling with L-pieces, backtracking, brute force, small cases, spotting the pattern, simple math.
10645 - Menu - DP, printing the solution.
10648 - Chocolate Box - DP, math, probability theory.
10650 - Determinate Prime - math, number theory, primes, sieve.
10651 - Pebble Solitaire - DP, bitmasks.
10654 - The Uxuhul Voting System - DP.
10655 - Contemplation! Algebra - math, complex numbers, linear algebra, linear transformation, linear recurrences, repeated squaring on a matrix.
10656 - Maximum Sum II - ad hoc.
10660 - Citizen Attention Offices - ad hoc, brute force, simple math, grids, manhattan distance.
10661 - The Perspectographer - graph theory, vertex coloring, computing the chromatic number of a graph, NP-complete, backtracking, pruning, lower bound by finding maximum clique size.
10662 - The Wedding - ad hoc, brute force.
10663 - Non-Powerful Subsets - maximal sets, greedy, DP, subset sum, simple math, powers.
10664 - Luggage - DP, subset sum.
10665 - Diatribe against Pigeonholes - DP, sorting, printing the lexicograpically smallest solution.
10666 - The Eurocup is here! - ad hoc, simple math, tournament tree, binary number system, number of bits, index of least significant bit.
10667 - Largest Block - maximum 2D sum (special case, reduction, see UVA 108), DP.
10668 - Expanding Rods - math, numerical analysis, bisection, root-finding, geometry, circles.
10669 - Three powers - math, binary number system, bignum.
10670 - Work Reduction - greedy.
10672 - Marbles on a tree - graph theory, trees, simple math, subtree sizes, DFS.
10673 - Play with Floor and Ceil - number theory, math.
10678 - The Grazing Cow - geometry, area of an ellipsis, Pythagoras' theorem, simple math.
10679 - I Love Strings!!! - strings, string matching, substring queries, suffix tree, suffix array, (or Aho-Corasick).
10680 - LCM - math, lcm of the first N integers, gcd, sieve, primes, prime powers.
10681 - Teobaldo's Trip - graph theory, reachability using k edges, adjacency matrix, repeated squaring, (or DP).
10682 - Forro Party - graph theory, BFS.
10683 - The decadary watch - ad hoc, simple math.
10684 - The Jackpot - maximum consecutive 1D sum, DP.
10685 - Nature - graph theory, DFS, connected components, finding the size of the largest connected component, union-find.
10688 - The Poor Giant - DP.
10689 - Yet Another Number Sequence - math, Fibonacci numbers, linear recurrences, modular arithmetic, linear algebra, linear transformations, repeated squaring on a matrix, (or Pisano period, periodicity, cycle finding).
10690 - Expression Again - DP, subset sum, math, minimizing/maximizing a product when the sum is constant.
10691 - Subway - computational geometry, sweepline algorithm on a circle, sorting, greedy, trigonometry.
10693 - Traffic Volume - math, calculus, derivative, local maximum, optimization, physics, velocity.
10694 - Combinatorial Summation - math, summations, changing the order of summation, binomial coefficients, Fibonacci numbers, partial sums, bignum.
10696 - f91 - ad hoc, math, recursion, McCarthy 91 function.
10697 - Firemen Barracks - computational geometry, perpendicular bisectors, line-line intersection, (floating-point precision problems).
10698 - Football Sort - ad hoc, simulation, sorting, pretty printing.
10699 - Count the Factors - math, number theory, sieve, primes, trial division.
10700 - Camel Trading - greedy, math, (or backtracking, DP).
10701 - Pre, in and post - graph theory, trees, tree traversal, reconstructing tree from preorder and inorder traversal.
10702 - Travelling Salesman - DP, graph theory.
10703 - Free Spots - ad hoc, simulation.
10704 - Traffic! - graph theory, shortest paths, BFS, searching, (Rush Hour game).
10705 - The Fun Number System - math, number base conversion.
10706 - Number Sequence - math, binary search.
10707 - 2-D Nim - graph theory, graph traversal, DFS, connected components, sorting, rotations, flips, canonical orderings, isomorphism.
10710 - Chinese Shuffle - ad hoc, math, repeated squaring, modulo.
10712 - Count the Numbers - DP.
10714 - Colliding Ants - greedy.
10716 - Evil Straw Warts Live - greedy.
10717 - Mint - ad hoc, math, gcd, lcm, brute force.
10718 - Bit Mask - ad hoc, greedy, bitmasks.
10719 - Quotient Polynomial - simple math, polynomials, division.
10720 - Graph Construction - graph theory, graphic sequence, Erdos-Gallai condition, (or greedy, Havel-Hakimi).
10721 - Bar Codes - DP.
10722 - Super Lucky Numbers - DP, bignum.
10723 - Cyborg Genes - DP, strings, shortest common supersequence.
10724 - Road Construction - graph theory, all-pairs shortest paths, APSP, Floyd-Warshall.
10728 - Help! - graph theory, graph traversal, DFS, strings.
10730 - Antiarithmetic? - ad hoc.
10731 - Test - graph theory, strongly connected components.
10733 - The Colored Cubes - math, number of face colorings of a cube under rotations, Burnside's lemma, orbits, abstract algebra, group theory, combinatorics, cubes, rotations.
10735 - Euler Circuit - graph theory, Euler tour in a mixed graph, max-flow, Euler tour.
10738 - Riemann vs. Mertens - number theory, sieve, primes.
10739 - String to Palindrome - DP, variation of edit distance.
10740 - Not the Best - graph theory, k'th shortest paths, single source shortest paths, SSSP, Dijkstra.
10745 - Dominant Strings - strings, trie, sorting.
10746 - Crime Wave - The Sequel - graph theory, minimum cost weighted bipartite matching (min-cost max-flow).
10747 - Maximum Subsequence - math, greedy, case analysis (special cases).
10750 - Beautiful Points - computational geometry, closest pair of points, sorting, divide and conquer.
10755 - Garbage Heap - maximum 3D sum (similar to UVA 108), DP.
10759 - Dice Throwing - DP, math, probability theory, fractions, rational arithmetic.
10763 - Foreign Exchange - ad hoc, sorting.
10766 - Organizing the Organization - graph theory, number of spanning trees of a graph, Kirchhoff's matrix tree theorem, linear algebra, matrices, Gaussian elimination, determinants, primes, fields.
10776 - Determine the Combination - combinatorics, generating all combinations of r letters given n letters, recursion, sorting.
10779 - Collector's Problem - graph theory, max-flow.
10780 - Again Prime? No time. - number theory, primes, prime factorization, sieve, factorials, math.
10783 - Odd Sum - ad hoc.
10784 - Diagonal - combinatorics, ad hoc.
10785 - The Mad Numerologist - ad hoc, sorting.
10787 - Modular Equations - ad hoc, simple math, modular arithmetic.
10789 - Prime Frequency - number theory, primes, counting, ad hoc.
10790 - How Many Points of Intersection? - combinatorics, math, binomial coefficients.
10791 - Minimum Sum LCM - number theory, math, gcd, lcm, primes, sieve, prime factorization.
10793 - The Orc Attack - graph theory, all-pairs shortest paths, Floyd-Warshall.
10799 - OOPS! They did it Again - math, arithmetic sequences, formula for an arithmetic sequence, summations, floors.
10800 - Not That Kind of Graph - ad hoc, simulation.
10801 - Lift Hopping - graph theory, shortest paths, SSSP, Dijkstra.
10802 - Lex Smallest Drive - graph theory, graph traversal, DFS, cycle detection, greedy, sorting.
10803 - Thunder Mountain - graph theory, all-pairs shortest paths, APSP, Floyd-Warshall.
10804 - Gopher Strategy - graph theory, maximum cardinality bipartite matching, binary search (bisection).
10805 - Cockroach Escape Networks - graph theory, minimum diameter spanning tree.
10806 - Dijkstra, Dijkstra - graph theory, min-cost max-flow, k shortest paths (k=2, edge disjoint).
10807 - Prim, Prim - graph theory, MST, Kruskal's algorithm, backtracking, data structures, union-find.
10810 - Ultra Quicksort - sorting, counting inversions, merge sort.
10812 - Beat the Spread - ad hoc.
10814 - Simplifying Fractions - simple math, gcd, bignum.
10815 - Andy's First Dictionary - ad hoc, sorting, string manipulation.
10816 - Travel in the Desert - graph theory, MST, shortest paths, SSSP, Dijkstra.
10817 - Headmaster's Headache - DP.
10819 - Trouble of 13-Dots - DP, 0/1 knapsack (a bit modified).
10820 - Send A Table - number theory, Euler phi/totient, recurrences, sieve.
10826 - Hot or Cold? - DP, math, number guessing game, hotter colder.
10827 - Maximum Sum on a Torus - maximum sum in 2D (see UVA 108), DP.
10828 - Back to Kernighan and Ritchie - systems of linear equations, Gaussian elimination, graph theory, graph traversal, reachability.
10830 - A New Function - number theory, summations, floors.
10831 - Gerg's Cake - number theory, quadratic residues, Legendre Symbol.
10842 - Traffic Flow - graph theory, MST.
10852 - Less Prime - number theory, primes, modulo.
10862 - Connect the Cable Wires - bignum, recurrences, number theory, Fibonacci numbers.
10864 - The Predator - computational geometry, rectangles, planar point location, coordinate compression, graph theory, DFS.
10878 - Decode the Tape - ad hoc, string manipulation, maps.
10879 - Code Refactoring - math, factoring, trial division.
10881 - Piotr's Ants - ad hoc, sorting.
10883 - Supermean - math, binomial coefficients.
10887 - Concatenation of Languages - hashing, hashtable.
10891 - Game of Sum - DP, memoization, games.
10892 - LCM Cardinality - number theory, gcd, lcm.
10897 - Travelling Distance - geometry, great circle distances.
10900 - So you want to be a 2n-aire? - math, probability theory (continuous), expectation, integration.
10901 - Ferry Loading III - ad hoc, simulation.
10902 - Pick-up sticks - computational geometry, line segment intersection.
10903 - Rock-Paper-Scissors Tournament - ad hoc
10905 - A Children's Game - ad hoc, sorting
10908 - Largest Square - ad hoc.
10909 - Lucky Numbers - data structures, BST, find element at given rank in a BST, splay tree, linear searching.
10910 - Mark's Distribution - DP, recurrences.
10911 - Forming Quiz Teams - DP, brute force, memoization (or graph theory, minimum weight maximal matching in general graphs).
10912 - Simple Minded Hashing - DP.
10913 - Walking on a Grid - DP, memoization.
10915 - War on Weather - geometry, angles, cosine relation.
10916 - Factstone Benchmark - ad hoc, math, logarithms.
10917 - Walk Through the Forest - graph theory, shortest paths, SSSP, Dijkstra, DAG, counting paths in a DAG, DP.
10918 - Tri Tiling - combinatorics, recurrences, DP.
10919 - Preqrequisites - ad hoc.
10920 - Spiral Tap - ad hoc, coordinate systems, simple math, (or fast simulation), (see UVA 903).
10921 - Find the Telephone - ad hoc.
10922 - 2 the 9s - ad hoc, number theory.
10924 - Prime Words - number theory, sieve, primes.
10925 - Krakovia - bignum.
10926 - How Many Dependencies? - graph theory, DFS, DAG.
10927 - Bright Lights - computational geometry, gradients, sorting, distances.
10929 - You can say 11 - number theory, modular arithmetic.
10931 - Parity - ad hoc, number base conversion.
10935 - Throwing cards away I - ad hoc, simulation, queue.
10938 - Flea Circus - data structures, trees, tree traversal, lowest common ancestor (LCA) queries.
10940 - Throwing Cards Away II - recurrences, math.
10943 - How do you add? - DP.
10945 - Mother Bear - ad hoc, palindromes.
10946 - You want what filled? - graph theory, flood fill, DFS (or BFS), sorting.
10948 - The Primary Problem - number theory, primes, sieve.
10949 - Kids in a Grid - LCS, string algorithms, Hunt-Szymanski algorithm (optimized version), (or some other fast LCS algorithm).
10951 - Polynomial GCD - polynomials, long division, gcd, math.
10953 - Stochastic Digit Generator - DP, math, modulo.
10954 - Add All - greedy.
10963 - The Swallowing Ground - ad hoc.
10964 - Strange Planet - ad hoc, math, modulo.
10970 - Big Chocolate - ad hoc, DP, memoization, recursion.
10976 - Fractions Again - brute force, math.
10977 - Enchanted Forest - graph theory, BFS, shortest paths, SSSP.
10982 - Troublemakers - graph theory, max cut, NP-complete, approximation algorithms, randomized algorithm, (or deterministic, greedy).
10983 - Buy one, get the rest free - graph theory, max-flow, binary search.
10986 - Sending email - graph theory, shortest paths, Dijkstra, SSSP.
10987 - AntiFloyd - graph theory, all-pairs shortest paths (in reverse), Floyd-Warshall.
10989 - Bomb, Divide and Conquer - graph theory, min-cut (not s-t min-cut), Stoer-Wagner.
10990 - Another New Function - number theory, primes, Euler totient, sieve (modified), prefix sums.
10991 - Region - geometry, cosine relation, triangle area, area of circle sector, Heron's formula.
10992 - The Ghost of Programmers - ad hoc, math, modulo (bignum).
10993 - Ignoring Digits - graph theory, BFS.
10994 - Simple Addition - recurrences, math, sums.
11000 - Bee - number theory, recurrences, Fibonacci numbers.
11001 - Necklace - ad hoc, brute force, maximization of a function.
11002 - Towards Zero - graph theory, DFS, DP, memoization.
11003 - Boxes - DP, LIS.
11005 - Cheapest Base - number theory, base conversion, ad hoc.
11008 - Antimatter Ray Clearcutting - DP, geometry, lines, collinearity.
11012 - Cosmic Cabbages - math, case analysis, manhattan distance.
11015 - 05-2 Rendezvous - graph theory, APSP, all-pairs shortests paths, Floyd-Warshall.
11022 - String Factoring - DP, strings, border array, minimal period.
11026 - A Grouping Problem - DP, math, elementary symmetric polynomials.
11027 - Palindromic Permutation - math, multinomial coefficients.
11028 - Sum of Product - math, precalculation, the dartboard sequence, permutations.
11029 - Leading and Trailing - math, modulo, repeated squaring.
11030 - Predator II - computational geometry, point in simple polygon.
11032 - Function Overloading - ad hoc, binary search.
11040 - Add Bricks in the Wall - ad hoc.
11044 - Searching For Nessy - ad hoc, simple math.
11045 - My T-Shirt Suits Me - graph theory, max-flow (or maximum cardinality bipartite matching).
11048 - Automatic Correction of Misspellings - ad hoc, strings, string matching.
11049 - Basic Wall Maze - graph theory, shortest paths, BFS.
11051 - Dihedral Groups - ad hoc.
11052 - Economic Phone Calls - DP, (or greedy).
11053 - Flavius Josephus Reloaded - cycle finding (Floyd's Cycle Finding Algorithm).
11054 - Wine Trading in Gergovia - ad hoc, greedy.
11055 - Homogeneous Squares - ad hoc, math.
11057 - Exact Sum - ad hoc.
11059 - Maximum Product - ad hoc, brute force.
11063 - B2 Sequence - ad hoc.
11064 - Number Theory - math, number theory, totient, divisors, primes, (see also UVA 10299).
11069 - A Graph Problem - combinatorics, recurrences.
11079 - What's the Time? - math, lcm, periodicity, simulation, fast simulation.
11081 - Strings - DP.
11082 - Matrix Decompressing - graph theory, max-flow.
11087 - Divisibility Testing - DP, math, modulo.
11090 - Going in Cycle!! - graph theory, minimum mean-weight cycle, Karp's minimum mean-weight cycle algorithm, (or shortest paths, Bellman-Ford).
11100 - The Trip 2007 - ad hoc, greedy, sorting, queue.
11101 - Mall Mania - graph theory, BFS, flood fill.
11103 - WFF 'N PROOF - binary trees, internal nodes, leaves.
11105 - Semi-prime H-numbers - number theory, sieve, prefix sums.
11107 - Life Forms - suffix array, strings.
11108 - Tautology - brute force, parsing, abstract evaluation, NP-complete.
11109 - Rinse - math, maximising a product.
11110 - Equidivisions - graph theory, flood fill, DFS.
11111 - Generalized Matrioshkas - ad hoc, stack.
11115 - Uncle Jack - bignum.
11118 - Prisoners Boxes and Pieces of Paper - probability theory, permutations, cycles.
11121 - Base -2 - math, number base conversion, negative bases.
11122 - Tri Tri - computational geometry, 2D triangle-triangle intersection.
11125 - Arrange Some Marbles - DP.
11126 - Relaxed Golf - DP.
11127 - Triple-Free Binary Strings - backtracking.
11129 - An Antiarithmetic Permutation - divide and conquer, math.
11133 - Eigensequences - DP, math.
11137 - Ingenuous Cubrency - DP, subset sum, coin change.
11138 - Nuts 'n' Bolts - graph theory, maximum cardinality bipartite matching.
11149 - Power of Matrix - matrices, matrix multiplication, repeated squaring (of matrices), DP.
11150 - Cola - ad hoc.
11151 - Longest Palindrome - DP, strings.
11152 - Colourful Flowers - geometry, circles, Heron's formula, incircle, circumcircle,
11153 - Museums - DP, TSP, bitmasks, graph theory, APSP, all-pairs shortest paths, Floyd-Warshall.
11155 - Be Efficient - ad hoc, number theory.
11156 - Continuous Drawing - computational geometry, line segments, lattice points, gcd, graph theory, Chinese postman problem, all-pairs shortest paths, Floyd-Warshall, minimum cost maximum matchings in general graphs, DP.
11157 - Dynamic Frog - greedy, sorting.
11158 - Elegant Permuted Sum - greedy, sorting, simple math, (or DP).
11159 - Factors and Multiples - graph theory, maximum cardinality bipartite matching, maximum independent set in a bipartite graph, simple math, divisibility.
11161 - Help My Brother - bignum, Fibonacci Numbers.
11162 - Independent Attacking Zones - DP, simple math, triangles, circles.
11167 - Monkeys in the Emei Mountain - graph theory, max-flow.
11170 - Cos(NA) - De Moivre's formula, Chebyshev polynomials, math.
11171 - SMS - DP, printing the solution, strings, trie.
11172 - Relational Operators - ad hoc.
11174 - Stand in a Line - number of topological sorts of a forest, linear extensions, graph theory, math, factorials, binomial coefficients, modular inverses (modulo a prime).
11176 - Winning Streak - DP, math, probability theory.
11180 - Base i-1 - math, complex numbers, division, complex bases, number base conversion.
11183 - Teen Girl Squad - graph theory, directed minimum spanning tree, minimum cost arborescence, Chu-Liu-Edmonds algorithm.
11185 - Ternary - ad hoc, number base conversion.
11191 - Perfect Square - number theory, primes, square numbers, math.
11192 - Group Reverse - ad hoc.
11200 - Sapitaur's Labyrinth - graph theory, reachability, flood-fill, BFS, mazes.
11201 - The Problem with the Crazy Linguist - backtracking, brute force, ad hoc.
11202 - The Least Possible Effort - graph theory, Knight's tour, math, counting symmetries, rotations, flips.
11203 - Can You Decide it for ME? - ad hoc.
11204 - Musical Instruments - ad hoc.
11205 - The Broken Pedometer - bit masks, brute force.
11207 - The Easiest Way - ad hoc, simple math, geometry, squares.
11218 - KTV - brute force, backtracking, ad hoc.
11219 - How old are you? - ad hoc.
11220 - Decoding the Message - ad hoc.
11221 - Magic Square Palindromes - ad hoc.
11222 - Only I did it! - ad hoc.
11223 - dah, dah, dah! - ad hoc.
11224 - Let's Swim - ad hoc, sorting.
11225 - Tarot Scores - ad hoc.
11226 - Reaching the fix-point - number theory, sieve (modified).
11227 - The Silver Bullet - ad hoc, geometry, straight lines, gradients, slopes.
11228 - Transportation System - graph theory, MST.
11230 - Annoying Painting Tool - greedy, simulation.
11231 - Black and white painting - ad hoc, counting, sums, floor, ceiling.
11232 - Cylinder - geometry, math, cylinders, volume of a cylinder.
11233 - Deli Deli - ad hoc, string manipulation.
11234 - Expressions - trees, postorder, level order, queues, stacks.
11235 - Frequent Values - data structures, Range Maximum Query, computational geometry, 1D range searching (augmented to get Range Max Query).
11236 - Grocery Store - ad hoc, brute force, pruning, no input.
11237 - Halloween Treats - number theory, pigeonhole principle, modulo.
11238 - Innumerous Bowling Games - DP, memoization.
11239 - Open Source - ad hoc, sorting, sets.
11240 - Antimonotonicity - greedy, number of runs in a sequence (or DP).
11241 - Humidex - ad hoc.
11242 - Tour De France - ad hoc, sorting.
11243 - Texas Trip - computational geometry, smallest enclosing square, ternary search, rotations, rotation matrices.
11244 - Counting Stars - ad hoc.
11245 - Anti-Arithmetic Sequence - math, number theory, modulo, primes, number base conversion.
11246 - K-Multiple Free Set - greedy, ad hoc.
11247 - Income Tax Hazard - ad hoc.
11254 - Consecutive Integers - number theory, divisors, Gauss sum, brute force.
11255 - Necklace - math, Burnside's lemma, orbits, abstract algebra, group theory, combinatorics, necklaces, rotations, gcd, binomial coefficients.
11256 - Repetitive Multiple - math, number theory, gcd, lcm.
11258 - String Partition - DP.
11259 - Coin Changing Again - DP, inclusion-exclusion principle (for queries).
11260 - Odd Root Sum - math, summations.
11261 - Bishops - ad hoc, games, chess, chess board, bishops, counting number of threathened squares, diagonals.
11262 - Weird Fence - graph theory, maximum cardinality bipartite matching, binary search.
11264 - Coin Collector - greedy.
11269 - Setting Problems - greedy, sorting, scheduling algorithms.
11270 - Tiling Dominoes - combinatorics, advanced math (google!).
11273 - Warping of N Dimensional Space - linear algebra, linear transformations, number theory, gcd, Euler phi, sieve.
11275 - 3D Triangles - computational geometry, 3D triangle intersection.
11277 - Cyclic Polygons - computational geometry, binary search, Heron's formula, triangulation, arc lengths.
11278 - One-Handed Typist - ad hoc.
11279 - Keyboard Comparison - ad hoc.
11280 - Flying to Fredericton - graph theory, shortest paths, SSSP, Bellman-Ford.
11281 - Triangular Pegs in Round Holes - geometry, minimal bounding circle for triangles, circumcircle, obtuse angles.
11282 - Mixing Invitations - combinatorics, binomial coefficients, derangements.
11283 - Playing Boggle - graph theory, DFS.
11284 - Shopping Trip - graph theory, DP, TSP, Floyd-Warshall, all-pairs shortest paths, APSP, memoization.
11285 - Exchange Rates - DP.
11286 - Conformity - ad hoc.
11287 - Pseudoprime Numbers - number theory, primality testing, trial division, repeated squaring.
11291 - Smeech - ad hoc, parsing, stacks.
11292 - Dragon of Loowater - ad hoc, greedy.
11294 - Wedding - 2-SAT.
11296 - Counting Solutions of an Integer Equation - ad hoc, math, floors.
11297 - Census - data structures, four-sided range queries, 2D range minimum/maximum queries, 2D segment tree (2D interval tree, range tree or similar), geometric data structures, augmenting data structures.
11301 - Great Wall of China - graph theory, min-cost max-flow.
11307 - Alternative Arborecsence - graph theory, trees, DP.
11308 - Bankrupt Banker - ad hoc.
11309 - Counting Chaos - ad hoc.
11310 - Delivery Debacle - math, recurrences.
11311 - Exclusively Edible - DP.
11312 - Flipping Frustation - number theory, extended GCD.
11313 - Gourmet Games - ad hoc.
11314 - Hardly Hard - geometry, calculus of several variables, partial derivatives, minimization.
11319 - Stupid Sequence - polynomial interpolation, Gaussian elimination, systems of linear equations.
11321 - Sort! Sort!! and Sort! - ad hoc, sorting.
11323 - Satisfying Constraints - graph theory, DFS, math.
11324 - The Largest Clique - graph theory, strongly connected components, DP, DAG, longest path.
11325 - This Means War - backtracking, brute force, greedy.
11326 - Laser Pointer - geometry, trigonometry.
11327 - Enumerating Rational Numbers - number theory, gcd, Euler totient, sieve.
11329 - Curious Fleas - graph theory, shortest paths, BFS, bitmasks.
11330 - Andy's Shoes - permutations, cycles, puzzles, greedy.
11331 - The Joys of Farming - graph theory, 2-coloring, DFS, subset sum, knapsack, DP.
11332 - Summing Digits - ad hoc.
11335 - Discrete Pursuit - math, gauss sum.
11336 - DRM - graph theory, graph traversal, DFS.
11338 - Minefield - geometry, sorting, graph theory, shortest paths, Dijkstra.
11340 - Newspaper - ad hoc.
11341 - Term Strategy - DP.
11342 - Three-Square - ad hoc, brute force.
11343 - Isolated Segments - computational geometry, line segment intersection.
11344 - The Huge One - ad hoc, number theory, modulo.
11345 - Rectangles - geometry, ad hoc.
11346 - Probability - math, probability theory, integration, continuous probability distribution.
11347 - Multifactorials - number theory, primes, prime factorization.
11348 - Exhibition - ad hoc.
11349 - Symmetric Matrix - ad hoc.
11350 - Stern-Brocot Tree - ad hoc, number theory.
11351 - Last Man Standing - Josephus problem.
11352 - Crazy King - graph theory, BFS.
11353 - A Different Kind of Sorting - number theory, sieve, primes, sorting.
11354 - Bond - data structures, graph theory, bottleneck edge queries in a static graph, minimum spanning tree, Kruskal's algorithm, union-find tree (using only union by rank or union by size), lowest common ancestor (LCA).
11355 - Cool Points - computational geometry, sweeping, sorting by polar angle.
11356 - Dates - ad hoc.
11357 - Ensuring Truth - ad hoc.
11358 - Faster Processing Facility - graph theory, max-flow (like UVA 11167).
11359 - Guards, Imbecile Guards - graph theory, BFS, cycle finding.
11360 - Have Fun With Matrices - ad hoc, simulation.
11361 - Investigating Div-Sum Property - DP, number theory, modulo.
11362 - Phone List - strings, sorting.
11363 - Cuckoo Hashing - ad hoc, cycle finding, cuckoo hashing.
11364 - Optimal Parking - ad hoc.
11365 - Copying DNA - graph theory, BFS, bitmasks, precalculation (optimization).
11367 - Full Tank - graph theory, shortest paths, SSSP, Dijkstra (with a heap).
11368 - Nested Dolls - greedy, sorting, (or Dilworth's theorem, LIS in O(nlogn), DP).
11369 - Shopaholic - greedy, sorting.
11370 - Moogle - DP.
11371 - Number Theory for Newbies - ad hoc.
11372 - Arranging a Contest - DP.
11373 - Happy Birthday - geometry, angles, sorting, circle sector area, triangle area, line-circle intersection, line-line intersection.
11374 - Airport Express - graph theory, shortest paths, SSSP, Dijkstra.
11375 - Matches - DP, bignum.
11377 - Airport Setup - graph theory, shortest paths, BFS.
11378 - Bey Battle - computational geometry, closest pair of points (using a different distance function), sorting.
11380 - Down Went the Titanic - graph theory, max-flow.
11381 - Elegant Strings - graph theory, minimum cost weighted bipartite matching (min-cost max-flow).
11383 - Golden Tiger Claw - Kuhn-Munkres (Hungarian) algorithm (byproduct of this algorithm), weighted maximum cardinality bipartite matching.
11384 - Help is needed for Dexter - ad hoc, math, recurrences.
11385 - Da Vinci Code - ad hoc, simulation
11386 - Triples - ad hoc, sorting, hashing.
11387 - The 3-Regular Graph - graph theory, ad hoc.
11388 - GCD LCM - number theory, gcd, lcm.
11389 - The Bus Driver Problem - ad hoc, sorting.
11390 - The Sultan's Feast - backtracking, (graph theory, strongly connected components).
11391 - Blobs in the Board - DP.
11392 - Binary*3 Type Multiple - math, number theory, modulo.
11393 - Tri-Isomorpishm - graph theory, ad hoc.
11394 - Digit Blocks - DP.
11395 - Sigma Function - number theory.
11396 - Claw Decomposition - graph theory, claws, testing if a graph is bipartite, DFS.
11398 - The Base-1 Number System - ad hoc.
11400 - Lighting System Design - DP.
11401 - Triangle Counting - geometry, triangles, math.
11402 - Ahoy, Pirates! - data structures.
11403 - Binary Multiplication - ad hoc.
11404 - Palindromic Subsequence - DP, strings, printing the solution, lexicographically smallest solution.
11405 - Can U Win? - graph theory, BFS, TSP.
11407 - Squares - ad hoc, brute force, math.
11408 - Count DePrimes - number theory, sieve, math, prefix sums.
11410 - LAEncoding - ad hoc, simple math, number base conversion.
11411 - MiniMice - number theory, sieve, primes, number of divisors, sorting, greedy.
11412 - Dig the Holes - ad hoc, brute force.
11413 - Fill The Containers - binary search, greedy.
11414 - Dream - graph theory, graphic sequence, Erdos-Gallai condition, (or greedy, Havel-Hakimi).
11415 - Count The Factorials - number theory, sieve, primes, factorials, binary search.
11417 - GCD - number theory, summations, gcd.
11418 - Clever Naming Patterns - graph theory, maximum cardinality bipartite matching.
11419 - SAM I AM - graph theory, minimum vertex cover in a bipartite graph, maximum-cardinality bipartite matching, König's theorem.
11420 - Chest of Drawers - DP.
11421 - Arranging Cards - DP.
11423 - Cache Simulator - data structures, binary indexed tree, Fenwick tree.
11424 - GCD Extreme I - number theory, Euler totient, sieve, summations, gcd.
11426 - GCD Extreme II - number theory, Euler totient, sieve, summations, gcd.
11427 - Expect the Expected - DP, math, probability theory.
11428 - Cubes - number theory, math, brute force.
11430 - ETS Problem Setting - math, binomial coefficents.
11432 - Busy Programmer - DP.
11436 - Cubes - Extreme - number theory, math, divisors, quadratic equations.
11437 - Triangle Fun - geometry, triangles.
11438 - Integer Transmission - DP, bignum.
11439 - Maximizing the ICPC - graph theory, maximum cardinality matching in general graphs (nonbipartite), Edmond's Blossom Algorithm, binary search.
11440 - Help Mr. Tomisu - number theory, math, primes, sieve, Euler totient, modular inverses.
11441 - Encoding/Decoding - DP.
11444 - Sum - math, summations, interchanging the order of summation, binomial theorem.
11446 - Where's The Back Button? - graph theory, cycles, (see TopCoder SRM 184 Div 1 1000, editorial).
11447 - Reservoir Logs - computational geometry, area of 2D polygon.
11448 - Who Said Crisis? - bignum, subtraction.
11450 - Wedding Shopping - DP.
11452 - Dancing the Cheeky Cheeky - ad hoc, strings, string period.
11455 - Behold My Quadrange - ad hoc, geometry.
11456 - Trainsorting - LIS (longest increasing subsequence), LDS (longest decreasing subsequence), combination of a LIS and LDS.
11457 - Classified - graph theory, finding LCA in a DAG, queries, data structures, lattices, cryptography, Dynamic Biba integrity model.
11461 - Square Numbers - ad hoc, simple math.
11462 - Age Sort - sorting.
11463 - Commandos - graph theory, shortest paths, BFS.
11464 - Even Parity - ad hoc, brute force (on the first row).
11465 - Count the Polygons - splitting set in two, generating subsets, binary search, math (geometry, polygons), (or backtracking, pruning).
11466 - Largest Prime Divisor - number theory, math, primes, sieve, divisors, trial division.
11470 - Square Sums - ad hoc.
11471 - Arrange the Tiles - DP.
11472 - Beautiful Numbers - DP.
11473 - Campus Roads - computational geometry, perimeter of polygon, simple math, vectors.
11474 - Dying Tree - ad hoc, graph theory, DFS (or union-find).
11475 - Extend to Palindromes - hashing, strings, palindromes (or Knuth-Morris-Pratt, KMP algorithm).
11478 - Halum - graph theory, minimum mean-weight cycle, Karp's minimum mean-weight cycle algorithm.
11479 - Is this the easiest problem? - geometry, triangles, simple math.
11480 - Jimmy's Balls - ad hoc, math.
11481 - Arrange the Numbers - math, binomial coefficients, DP, recurrences, derangements.
11482 - Building a Triangular Museum - ad hoc, simulation.
11483 - Code Creator - ad hoc.
11485 - Extreme Discrete Simulation - DP.
11489 - Integer Game - ad hoc, simple math, modular arithmetic.
11491 - Erasing and Winning - greedy.
11492 - Babel - graph theory, shortest paths, SSSP, Dijkstra.
11493 - The Club Ballroom - ad hoc, greedy, simple math.
11494 - Queen - ad hoc.
11495 - Bubbles and Buckets - sorting, counting inversions, merge sort.
11496 - Musical Loop - ad hoc.
11497 - Set - ad hoc.
11498 - Division of Nlogonia - ad hoc.
11499 - Longest Increasing Subsequence - ad hoc.
11500 - Vampires - math, probability theory, (or DP).
11502 - Rocket Stages - DP, simple physics, math, calculus, integration.
11503 - Virtual Friends - graph theory, connected components, data structures, union-find.
11504 - Dominos - graph theory, strongly connected components, DAG.
11505 - Logo - ad hoc, simulation, simple math, cosine, sine.
11506 - Angry Programmer - graph theory, max-flow, max-flow min-cut theorem, vertex capacities.
11507 - Bender B. Rodriguez Problem - ad hoc, simulation, permutations, geometry.
11508 - Life on Mars - ad hoc.
11511 - Frieze Patterns - ad hoc, cycle finding.
11512 - GATTACA - strings, repetitions, substrings, hashing, (or suffix arrays, LCP).
11513 - 9 Puzzle - graph theory, shortest paths, BFS (from the goal state), printing the path.
11514 - Batman - DP.
11515 - Cranes - DP (or brute force), circle-circle intersection, circle area.
11516 - WiFi - binary search, greedy, interval covering.
11517 - Exact Change - DP, coin change.
11518 - Dominos 2 - graph theory, graph traversal, DFS.
11519 - Logo 2 - ad hoc, simulation, simple math, cosine, sine.
11520 - Fill the Square - greedy.
11522 - Pyramid Number - math, Egyptian fractions, Egyptian number, strictly Egyptian number (A051882 on OEIS).
11523 - Recycling - DP (see Topcoder SRM 240 Div 1 900).
11524 - In-Circle - geometry, math, binary search, circles, in-circle, triangles, triangle area, Heron's formula.
11525 - Permutation - math, permutations, factoradics, factorial number system, data structures, finding an element at a given rank, BST, binary search trees.
11526 - H(n) - simple math, floors, sums, square root.
11530 - SMS Typing - ad hoc, simulation.
11532 - Simple Adjacency Maximization - DP, (or greedy).
11534 - Say Goodbye to Tic-Tac-Toe - combinatorial game theory, composite games, Sprague-Grundy theorem, grundy numbers, impartial games, nim.
11535 - Set of Marbles - gray code, reflected binary code, binary numeral system.
11536 - Smallest Sub-Array - ad hoc, binary search, data structures, arrays.
11537 - Secret Problemsetter's Union - ad hoc, simulation, data structures, arrays.
11538 - Chess Queen - math, summations, closed form, number of non-attacking position of two queens on a m x n chessboard.
11539 - Another Word Game - DP, strings, hashing.
11540 - Sultan's Chandelier - math, Burnside's lemma, orbits, abstract algebra, group theory, combinatorics, rotations, gcd, primes, inverses, DP, graph theory, trees, tree isomorphism.
11541 - Decoding - ad hoc, strings, run-length encoding.
11542 - Square - math, linear algebra, subspaces, dimension, gaussian elimination over the field F_2, rank of a matrix, primes, sieve.
11544 - Recruiter's Problem - graph theory, max-flow, reusing the flow, searching, (or min-cost max-flow, Bignum).
11545 - Avoiding Jungle in the Dark - graph theory, shortest paths, BFS.
11547 - Automatic Answer - ad hoc, simulation, simple math.
11548 - Blackboard Bonanza - ad hoc, brute force, strings.
11549 - Calculator Conundrum - ad hoc, simple math, cycle finding (Floyd's cycle finding algorithm).
11550 - Demanding Dilemma - graph theory, incidence matrix, verifying correctness of an incidence matrix, detecting multiple edges between vertices.
11551 - Experienced Endeavour - linear algebra, linear transformations, matrices, matrix multiplication, repeated squaring (of matrices), modular arithmetic.
11552 - Fewest Flops - DP, strings.
11553 - Grid Game - DP, bitmasks.
11554 - Hapless Hedonism - math, recurrences, number of triangles possible using sticks of length 1,2,...,n.
11555 - Aspen Avenue - DP, sorting, greedy.
11556 - Best Compression Ever - ad hoc, simple math.
11557 - Code Theft - strings, longest common substring, hashing, rolling hash, (or suffix tree).
11558 - Dinner - graph theory, branch and bound, backtracking, brute force.
11559 - Event Planning - ad hoc.
11560 - Fixing the Bugs - DP, greedy, math, probability theory, expectation.
11561 - Getting Gold - graph theory, graph traversal, DFS.
11562 - Hard Evidence - computational geometry, maximal viewing angle of a convex polygon from a circle, sweepline on a circle, math, trigonometry, angles, ternary search.
11563 - Introspective Caching - greedy, caching, optimal caching strategy, data structures, priority queue, BST.
11564 - Just A Few More Triangles - number of Pythagorean triples mod n, modular arithmetic, Fast Fourier Transform (FFT) (will get TLE), multiplicative function, number theory, prime factorization, OEIS (A062775).
11565 - Simple Equations - ad hoc, simple math, divisors.
11567 - Moliu Number Generator - ad hoc, brute force, recursion.
11569 - Lovely Hint - DP.
11572 - Unique Snowflakes - ad hoc, longest substring with no duplicate characters, (or divide and conquer, coordinate compression).
11573 - Ocean Currents - graph theory, shortest paths, BFS (0/1 weights), deque.
11574 - Colliding Traffic - ad hoc, simple math, quadratic equations, angles, trigonometry.
11576 - Scrolling Sign - ad hoc, string manipulation, prefix, suffix.
11577 - Letter Frequency - ad hoc.
11578 - Situp Benches - DP, printing the solution.
11579 - Triangle Trouble - geometry, math, triangle area, Heron's formula, equilateral triangles, sorting.
11581 - Grid Successors - ad hoc, cycle detection.
11582 - Colossal Fibonacci Numbers! - math, Fibonacci numbers, cycle detection, Pisano period, repeated squaring.
11583 - Alien DNA - greedy, string manipulation, set intersection.
11584 - Partitioning By Palindromes - DP.
11585 - Nurikabe - ad hoc, simulation, games, nurikabe, solution verification, graph theory, DFS, flood fill.
11586 - Train Tracks - DP.
11587 - Brick Game - DP, games, winning/losition positions, reduction to SAT, backtracking.
11588 - Image Coding - ad hoc.
11590 - Prefix Lookup - strings, trie, DP.
11594 - All Pairs Maximum Flow - graph theory, maximum flow, all-pairs maximum flow, max-flow min-cut theorem, Gomory-Hu tree of minimum cuts (cut trees).
11596 - Convex Orthogonal Polygon - geometry, convex orthogonal polygons, bounding box, simple math, quadratic equations, divisors.
11597 - Spanning Subtree - graph theory, maximum number of edge-disjoint spanning trees in a complete graph.
11598 - Optimal Segments - DP, printing the solution, finding the lexicographically smallest solution.
11600 - Masud Rana - graph theory, spanning trees, complete graph, random walks, math, probability theory, DP, keeping track of the connected components.
11601 - Avoiding Overlaps - ad hoc, data structures, bitsets, geometry, rectangle-rectangle intersection, fast I/O.
11602 - SMS for Blinds - backtracking, brute force, sorting, pruning.
11603 - It's all about the Bandwidth - graph theory, maximum spanning tree, DFS, bottleneck edge queries, all-pairs maximum flow, max-flow min-cut theorem, Gomory-Hu tree of minimum cuts (cut trees).
11604 - General Sultan - strings, prefix, graph theory, reachability, DFS.
11605 - Lights inside a 3D Grid - math, probability theory, expected value, 0-1 indicator random variables, linear algebra, linear transformations, repeated squaring on a matrix, independence of dimensions, (or eigenvalues, eigenvectors, diagonalization, doubly stochastic matrix).
11606 - Atoms - ad hoc, simulation, manhattan distance, BFS, games, checking if a game state is reachable.
11608 - No Problem! - ad hoc, simulation.
11609 - Teams - math, summations, binomial coefficients, repeated squaring.
11610 - Reverse Prime - math, primes, sieve, data structures, binary indexed tree, Fenwick tree, dynamic cumulative sum, binary search.
11611 - Colored Tiles - DP, bitmasks, tiling, grids.
11612 - Sultan and Khairun Shundori - computational geometry, connecting a set of points with straight lines without crossings, collinearity, left/right turn, sorting by polar angle, sweepline on a circle.
11613 - Acme Corporation - graph theory, max-cost flow, reduction to max-cost max-flow, (or discrete ternary search).
11614 - Etruscan Warriors Never Play Chess - simple math, summations, sum of first n integers, quadratic equation.
11615 - Family Tree - ad hoc, simple math, complete binary trees.
11616 - Roman Numerals - ad hoc, conversion from roman numerals to decimal (and vice versa).
11617 - An Odd Love - DP.
11618 - The Amazing Triangle Counting Machine - graph theory, counting triangles.
11619 - Spam! (or not) - simple math, probability theory, Bayesian spam filtering (see Wikipedia).
11620 - City of Egocentrics - ad hoc, simple math, grids, prefix sums on rows, columns, and diagonals.
11621 - Small Factors - ad hoc, brute force, simple math.
11623 - Tic Tac Toe - ad hoc, N x N tic tac toe, board games, evaluating board positions.
11624 - Fire! - graph theory, BFS, multiple sources, shortest paths.
11625 - Nice Prefixes - strings, prefix, DP, linear algebra, linear transformations, repeated squaring on a matrix.
11626 - Convex Hull - computational geometry, convex hull, sorting by polar angle.
11627 - Slalom - sorting, binary search, simple math.
11628 - Another Lottery - ad hoc, simple math, probability theory, fractions, gcd.
11629 - Ballot Evaluation - ad hoc, simulation, simple math.
11631 - Dark Roads - graph theory, MST.
11632 - Elias Gamma Coding - DP, binary codes.
11633 - Food Portion Size - ad hoc, brute force, simple math, fractions, gcd.
11634 - Generate Random Numbers - ad hoc, simple math, cycle finding.
11635 - Hotel Booking - graph theory, single source shortest paths, SSSP, Dijkstra (with a heap).
11636 - Hello World - ad hoc, simple math, binary expansion, most significant bit.
11637 - Garbage Remembering Exam - math, probability theory, expectation.
11638 - Temperature Monitoring - ad hoc, simulation, bitmasks.
11639 - Guard the Land - ad hoc, geometry, rectangle-rectangle intersection.
11641 - Looking for a New Place - ad hoc, simple math, polyminoes, bounding box, geometry, brute force.
11642 - Bangladesh Premier League - graph theory, max-flow, min-cut.
11643 - Knight Tour - graph theory, BFS, shortest paths, TSP, DP, knight tour.
11644 - Pyragrid - ad hoc, geometry, counting triangles, graph theory.
11645 - Bits - ad hoc, simple math, recurrences, Bignum.
11646 - Athletics Track - math, binary search, plane geometry, rectangle, circle, circular sector, chord.
11647 - Judgment Day - graph theory, min-cost circulation, min-cost max-flow.
11648 - Divide The Land - math, binary search, plane geometry, area of trapezium, median of trapezoid.
11649 - Home! Sweet Home! - sorting, greedy, partial orders, data structures, BST.
11650 - Mirror Clock - ad hoc, simple math, analogue clock, reflection.
11651 - Krypton Number System - math, number bases, graph theory, number of paths of a fixed length, linear algebra, matrix multiplication, repeated squaring.
11653 - Stick Makes Gold - sweepline in 1D, sorting, math, sums, Gauss sum, sum of squares, sum of cubes.
11654 - Arithmetic Subsequence - DP, number of subsequences that are arithmetic progressions.
11655 - Water Land - graph theory, DAG, DP, number of paths from s to t, DFS, reachability.
11658 - Best Coalitions - DP, subset sum.
11659 - Informants - backtracking.
11660 - Look-and-Say sequences - ad hoc, brute force, string manipulation, math, look-and-say sequence.
11661 - Burger Time? - ad hoc, simulation.
11664 - Langton's Ant - ad hoc, simulation, bignum, number base conversion, cellular automata, Langton's ant, 2D Turing Machine.
11665 - Chinese Ink - computational geometry, simple polygons, polygon intersection, graph theory, DFS, connected components.
11666 - Logarithms - simple math, logarithms, brute force.
11677 - Alarm Clock - ad hoc, simulation.
11678 - Cards' Exchange - ad hoc, set intersection.
11679 - Sub-Prime - ad hoc, simulation.
11680 - Dragster - DP, math, probability theory, trees, graph theory, topological sorting.
11683 - Laser Sculpture - ad hoc.
11686 - Pick up Sticks - graph theory, topological sorting, DAG, detecting cycles.
11687 - Digits - ad hoc, simulation.
11688 - Rotate to root - binary search trees, rotations, move-to-root, computing height of tree after rotation to root for all nodes, recursion.
11689 - Soda Surpler - ad hoc, simulation, simple math.
11690 - Money Matters - graph theory, graph traversal, DFS, connected components.
11691 - Allergy Test - DP.
11693 - Speedy Escape - graph theory, shortest paths, SSSP, Dijkstra, binary search, (or MST, greedy, Prim's algorithm).
11695 - Flight Planning - graph theory, trees, diameter of a tree, center of a tree, graph traversal, DFS.
11696 - Beacons - computational geometry, sweepline by distance, sorting, distance, angles, circles, tangents, trigonometry, data structures, interval data structure, merging intervals, graph theory, DFS, connected components.
11697 - Playfair Cipher - ad hoc, simulation, playfair cipher.
11698 - Code Permutations - DP, math, permutations, order of a permutation, gcd, lcm, divisors, binomial coefficients, factorial.
11699 - Rooks - ad hoc, all subsets, bitmasks, chessboard, rooks, covering squares on a chessboard.
11700 - Pipes - DP, bitmasks.
11701 - Cantor - simple math, Cantor set, base 3, converting from decimal fraction to ternary.
11702 - Meltdown - computational geometry, simple polygons, ternary search, distance from point to line segment.
11703 - sqrt log sin - ad hoc, simulation, simple math.
11704 - Caper Pizza - computational geometry, angles, sweepline on a circle, sorting.
11705 - Grasshopper - graph theory, shortest paths, BFS.
11706 - Party Night - graph theory, "clique", testing if a graph is bipartite, 2-colorability, odd cycles, DFS.
11707 - Pachinko - computational geometry, line segments, graph theory, reachability.
11708 - Lexicographical Ranking - DP, simple math, binary search.
11709 - Trust Groups - graph theory, strongly connected components.
11710 - Expensive Subway - graph theory, MST.
11711 - Turing - ad hoc, simulation, turing machine.
11712 - Gnirut - ad hoc, simulation, turing machine.
11713 - Abstract Names - ad hoc, simulation, string manipulation.
11714 - Blind Sorting - comparison model, finding smallest and second smallest elements with the minimum number of comparisons, tournament tree, lower bound, decision tree.
11715 - Car - physics, kinematics formulas, equations, simple math.
11716 - Digital Fortress - ad hoc, simulation, string manipulation, encryption.
11717 - Energy Saving Microcontroller - ad hoc, simulation.
11718 - Fantasy of Summation - summations, simple math, repeated squaring.
11719 - Gridland Airports - graph theory, number of spanning trees of a complete bipartite graph, Kirchhoff's matrix tree theorem, linear algebra, matrices, determinants, math, repeated squaring.
11720 - How Many Ways - math, number of partitions of n into k distinct parts, number of partitions of n into parts whose greatest part is k, graph theory, adjacency matrix, number of paths of a fixed length, matrix multiplication, repeated squaring on matrices, linear algebra.
11721 - Instant View of Big Bang - graph theory, detecting negative weight cycles, Bellman-Ford, shortest paths, SSSP, strongly connected components, DAG, DP.
11722 - Joining With Friend - math, continuous probability theory, meeting probabilities, shape of coincidence, integration, area under curves, intervals, case analysis.
11723 - Numbering Roads - ad hoc, simple math.
11724 - Evaluate the Expression - greedy, graph theory, DAG, topological sorting, DFS, parsing, recursive descent parsing, operator precedence grammar.
11725 - Colorful Board - DP, bitmasks, profile DP.
11727 - Cost Cutting - ad hoc.
11728 - Alternate Task - precalculation, math, number theory, divisors, sums of divisors.
11729 - Commando War - greedy, sorting, scheduling algorithms.
11730 - Number Transformation - graph theory, shortest paths, BFS, number theory, primes, prime factorization.
11732 - "strcmp()" Anyone? - strings, trie, strcmp, number of comparisons, simple math, fast I/O.
11733 - Airports - graph theory, MST, Kruskal's algorithm, union-find.
11734 - Big Number of Teams Will Solve This - ad hoc, string manipulation.
11736 - Debugging Ram - ad hoc, simulation.
11737 - Extreme Primitive Society - ad hoc, simple math.
11742 - Social Constraints - ad hoc, brute force.
11743 - Credit Check - ad hoc, string manipulation.
11744 - Parallel Carry Adder - ad hoc, simulation, simple math.
11745 - Slitherlink - ad hoc, games, logic games, slitherlink, verifying if a solution is valid, graph theory, DFS, cycles.
11747 - Heavy Cycle Edges - graph theory, MST, heaviest edge on a cycle.
11748 - Rigging Elections - graph theory, DFS, reachability.
11749 - Poor Trade Advisor - simple math, graph theory, DFS, connected components.
11751 - Installing Diagnostic Software - simple math, greedy, binary number system, sorting.
11752 - The Super Powers - ad hoc, simple math, square root, sorting, no input.
11753 - Creating Palindrome - DP, palindromes, minimum number of insertions needed to make a string palindromic.
11755 - Table Tennis - DP, math, probability theory, table tennis, cycles, Gaussian elimination.
11757 - Winger Trial - graph theory, max-flow, min-cut, max-flow min-cut theorem, vertex capacities, geometry, circles, circle-circle intersection.
11758 - Left Right - combinatorial game theory, nim, Bogus Nim, Moore's Nim, DP, binomial coefficients, repeated squaring.
11759 - IBM Fencing - computational geometry, sorting, area, perimeter, point in convex polygon, graph theory, connected components.
11760 - Brother Arif, please feed us! - ad hoc.
11762 - Race to 1 - DP, math, probability theory, primes, sieve.
11764 - Jumping Mario - ad hoc.
11765 - Component Placement - graph theory, minimum cut, maximum flow, max-flow min-cut theorem.
11766 - Racing Car Computer - DP.
11768 - Lattice Point or Not - geometry, lattice points, number of lattice points on a line segment, math, gcd, linear diophantine equations, extended gcd, Bezout's identity.
11769 - All Souls Night - computational geometry, 3D convex hull, surface area, point in plane, area of 3D triangle, linear algebra, math.
11770 - Lighting Away - graph theory, strongly connected components, DAG, number of sources.
11780 - Miles 2 Km - ad hoc, simple math, fibonacci numbers, brute force, DP, precalculation.
11782 - Optimal Cut - DP, trees, graph theory.
11783 - Nails - computational geometry, line segment intersection.
11784 - Escape - ad hoc, simple math, geometry, rectangles, distance on the perimeter of a rectangle.
11785 - Hypercube - ad hoc, graph theory, Hamming cube, hypercube graph, checking if a graph is a Hamming cube.
11786 - Global Raining at Bididibus - ad hoc, water flow.
11787 - Numeral Hieroglyphs - ad hoc, simple math.
11790 - Murcia's Skyline - DP, weighted LIS.
11792 - Krochanska is Here! - graph theory, shortest paths, BFS.
11793 - Electoral Districts - ad hoc, backtracking, precalculation.
11804 - Argentina - ad hoc, brute force, bactracking.
11805 - Bafana Bafana - ad hoc, simple math.
11806 - Cheerleaders - math, binomial coefficients, inclusion-exclusion, (or DP).
11808 - Ensuring Victory - parsing, recursive descent parsing, operator precedence grammar, parse tree, math, calculus, differentiation, evaluating arithmetic expressions, fractions, gcd.
11809 - Floating-Point Numbers - math, floating point numbers, mantissa, exponent, logarithms.
11812 - Innovative Procession Management - graph theory, shortest paths, SSSP, Dijkstra, shortest path DAG, reconstructing the path.
11813 - Shopping - graph theory, Dijkstra, shortest paths, SSSP, DP, TSP.
11815 - Ideas - graph theory, graph traversal, BFS, queue.
11816 - HST - ad hoc, simulation, simple math.
11817 - Tunnelling The Earth - geometry, spherical coordinate system, cartesian coordinate system, coordinate system conversion, longitude, latitude, great circle distance.
11818 - Game - Mouse and Cheese - DP, bitmasks, all subsets, winning/losing positions, games, graph theory, graph traversal, reachability, DFS.
11821 - High-Precision Number - ad hoc, simple math, bignum, bigdecimal, addition, subtraction, formatting numbers.
11825 - Hackers' Crackdown - DP, bitmasks, all subsets, iterating over all subsets of a set.
11827 - Maximum GCD - ad hoc, brute force, simple math, gcd.
11987 - Almost Union Find - data structures, union-find, augmenting data structures.
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