Problems

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Total results29,455 problems

Black Square
Medium5
Implementation, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hands of Poker
Medium5
Sorting, Hash map+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Defense of a Kingdom
Medium5
Sorting, Greedy+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Sangkeun Tower
Medium5
Dynamic programming, Brute force+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Database
Medium5
Brute force, Hash map+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bureaucracy
Medium5
Simulation, Implementation+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Circles on a Screen
Medium5
Geometry, Simulation+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Enchanted Mirror
Medium5
Hash map, String+2
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Key to Success
Medium5
Greedy, Math+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Equation
Medium5
Stack, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
i18n
Medium5
String, Hash map+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
History of Football
Medium5
Backtracking, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Family Tree
Medium5
Tree, Greedy+1
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Drying
Medium5
Binary search, Greedy
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Flip and Turn
Medium5
Matrix, Simulation+1
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Godfather
Medium5
Tree, DFS+1
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Horn Clauses
Medium5
Graph, Implementation+1
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Graph Matching
Medium5
Dynamic programming, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Breaking the Cipher
Medium5
Combinatorics, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
L Puzzle
Medium5
Greedy, Simulation+1
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Stock Prices
Medium5
Simulation, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Industrial Spy's Letter
Medium5
Backtracking, Combinatorics+1
No attempts yet
Time limit
1.5s
Memory limit
128 MB
Judgeable
Simple Polygon
Medium5
Geometry, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Container
Medium5
Math, Brute force+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pie
Medium5
Binary search, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
JBC
Medium5
Math, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Highway
Medium5
Greedy, Geometry+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Computers
Medium5
Dynamic programming, Array
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Stable Marriage Problem
Medium5
Greedy, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Arne Saknussemm
Medium5
String, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Linear World
Medium5
Simulation, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Network Connection
Medium5
Union-find, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
How do spiders walk on water?
Medium5
Math, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Distributing Ballot Boxes
Medium5
Binary search, Greedy
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Game, Set and Match
Medium5
Dynamic programming, Probability+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Non-negative Partial Sums
Medium5
Prefix sum, Array
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
3-Sided Dice
Medium5
Geometry, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Minimal Backgammon
Medium5
Dynamic programming, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bug Hunt
Medium5
Simulation, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sum of Distinct Primes
Medium5
Dynamic programming, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Maximum Sum
Medium5
Dynamic programming, Sorting
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pathological Paths
Medium5
String, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Area of Polygons
Medium5
Geometry, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Faulhaber's Triangle
Medium5
Dynamic programming, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Windmill Animation
Medium5
Geometry, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Candy Distribution
Medium5
Number theory, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Factorials and Powers
Medium5
Number theory, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Router Placement to Minimize Maximum TTL
Medium5
Tree, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Counterattack
Medium5
Dynamic programming, Array+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Soccer Bets
Medium5
Graph, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Good Words
Medium5
Stack, String+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Voyager 1
Medium5
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
I've Got Your Back(gammon)
Medium5
Combinatorics, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pool Balls
Medium5
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pro-Test Voting
Medium5
Dynamic programming, Greedy
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Flipper
Medium5
Simulation, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Emma Loves Parties
Medium5
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sudoku
Medium5
Backtracking, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Lemmings, Lemmings Everywhere. But Not For Long.
Medium5
Simulation, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Once Around the Lock
Medium5
Simulation, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
And Now, a Remainder from Our Sponsor
Medium5
Number theory, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Caterpillar
Medium5
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Folding Game
Medium5
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Balloons
Medium5
Greedy, Sorting
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Largest Square
Medium5
Dynamic programming, Matrix
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Palindrometer
Medium5
String, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Skyline
Medium5
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Underground Cables
Medium5
Minimum spanning tree, Graph+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Block Game
Medium5
BFS, Simulation+1
No attempts yet
Time limit
10s
Memory limit
128 MB
Judgeable
A No-Win Situation
Medium5
Simulation, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Meganominoes
Medium5
Hash map, Brute force+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Buying Gas
Medium5
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Next Prime
Medium5
Number theory, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bridges and Tunnels
Medium5
Union-find, Hash map+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Buzzwords
Medium5
String, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ferry Loading V
Medium5
Dynamic programming, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Frosh Week
Medium5
Sorting, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cantor Set
Medium5
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Scrolling Sign
Medium5
Dynamic programming, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Logo 2
Medium5
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Curvy Little Bottles
Medium5
Math, Binary search+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ancient Hieroglyphs
Medium5
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
192 MB
Judgeable
Open Source
Medium5
Hash map, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tour de France
Medium5
Sorting, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Team Rankings
Medium5
Brute force, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Chat Rooms
Medium5
Sliding window, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hermes' Colony
Medium5
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ball Toss
Medium5
Simulation, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Plugged In
Medium5
Implementation, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Flipping Colors
Medium5
Recursion, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
War on Weather
Medium5
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Factstone Benchmark
Medium5
Math, Binary search+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bungee Jumping
Medium5
Math, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Catamaran Ballast
Medium5
Dynamic programming, Brute force
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Evil Straw Warts Live
Medium5
Greedy, Two pointers+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Perfect P-th Power
Medium5
Number theory, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Calories from Fat
Medium5
Math, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Genealogical Research
Medium5
Recursion, Tree+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Treasure Map
Medium5
Geometry, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ferry Loading II
Medium5
Greedy, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Black SquareGiven one row of an m×n grid known to contain a black s×s square, determine if the square's position is unique, ambiguous, or impossible from that row alone.	Medium5	ImplementationMath+1	No attempts yet	1s	128 MB	Judgeable
Hands of PokerGiven a five card poker hand, compute its unique rank value from 1 to 7462 that orders all possible hands consistently.	Medium5	SortingHash map+1	No attempts yet	1s	128 MB	Judgeable
Defense of a KingdomGiven tower positions that block whole rows and columns on a grid, find the area of the largest rectangle of cells left undefended.	Medium5	SortingGreedy+1	No attempts yet	3s	256 MB	Judgeable
Sangkeun TowerFor each elevator, find the minimum floor above 0 reachable using exactly n button presses (up/down moves), never going below 0, then take the overall minimum across elevators.	Medium5	Dynamic programmingBrute force+1	No attempts yet	1s	128 MB	Judgeable
DatabaseDetect whether any two rows in a table share equal values in two distinct columns, and if so output the lexicographically smallest violating row and column pair.	Medium5	Brute forceHash map+1	No attempts yet	1s	128 MB	Judgeable
BureaucracyGiven a sequence of declare and cancel operations forming a chain, determine which laws remain active where a law is active only if no active law cancels it.	Medium5	SimulationImplementation+1	No attempts yet	3s	256 MB	Judgeable
Circles on a ScreenGiven up to 100 circles drawn on a w×h grid, count how many pixels remain black after the union of circles is painted white.	Medium5	GeometrySimulation+1	No attempts yet	3s	256 MB	Judgeable
Enchanted MirrorDecide if bricks with fixed (real,mirror) letter pairs can be permuted so the row reads T1 and its mirror reads T2, given initial words S1,S2.	Medium5	Hash mapString+2	No attempts yet	3s	256 MB	Judgeable
Key to SuccessGiven n existing coin values and m coins to add freely, choose the added values to maximize the smallest positive integer not representable as a subset sum.	Medium5	GreedyMath+1	No attempts yet	3s	256 MB	Judgeable
EquationEvaluate a postfix expression containing at most one occurrence of variable X as a linear function ax+b, then solve ax+b=0 for x as a reduced fraction, handling no-solution and infinite-solution cases.	Medium5	StackMath+1	No attempts yet	1s	128 MB	Judgeable
i18nGiven text lines, expand i18n-style abbreviations back into previously seen full words when the expansion is valid and unique, preserving capitalization and separators.	Medium5	StringHash map+1	No attempts yet	1s	128 MB	Judgeable
History of FootballGiven final points of n (up to 8) football teams under win/draw/loss scoring, count the number of distinct match outcome assignments consistent with those totals.	Medium5	BacktrackingCombinatorics+1	No attempts yet	2s	64 MB	Judgeable
Family TreeGiven a tree where each node lists its single child (parent-of relation), compute the minimum number of extra ancestor nodes to insert so no node has more than d parents.	Medium5	TreeGreedy+1	No attempts yet	2s	64 MB	Judgeable
DryingGiven drying times per cloth that decrease by 1 each minute (or by k for one chosen cloth per minute on a radiator), find the minimum total minutes to dry all clothes, solved via binary search on time.	Medium5	Binary searchGreedy	No attempts yet	2s	64 MB	Judgeable
Flip and TurnSimulate up to 100000 sequential matrix transformations (transpose, flip, rotate) efficiently and output the final matrix.	Medium5	MatrixSimulation+1	No attempts yet	2s	64 MB	Judgeable
GodfatherGiven an undirected tree, find all vertices that minimize the largest connected component size after removal (the tree centroid(s)).	Medium5	TreeDFS+1	No attempts yet	2s	64 MB	Judgeable
Horn ClausesParse Horn clause formulas and decide satisfiability by computing the minimal true-variable assignment via forward chaining, or report unsatisfiable.	Medium5	GraphImplementation+1	No attempts yet	2s	64 MB	Judgeable
Graph MatchingCount the number of matchings (independent edge sets) of the cycle graph C_n for each given n, likely requiring big-integer arithmetic via a Lucas-sequence style recurrence.	Medium5	Dynamic programmingMath+1	No attempts yet	1s	128 MB	Judgeable
Breaking the CipherGiven plaintext, ciphertext, and block size, count permutations of size k that transform every plaintext block into the matching ciphertext block.	Medium5	CombinatoricsString+1	No attempts yet	1s	128 MB	Judgeable
L PuzzleDetermine whether a black/white grid pattern can be exactly tiled by L-shaped pieces, each with one black corner cell and two adjacent white cells.	Medium5	GreedySimulation+1	No attempts yet	5s	128 MB	Judgeable
Stock PricesSimulate an order book with buy and sell orders, matching bids and asks at the ask price, and report ask, bid, and last trade price after each order.	Medium5	SimulationImplementation+1	No attempts yet	1s	128 MB	Judgeable
The Industrial Spy's LetterGiven up to 7 digit shreds, count the distinct primes formable by arranging any subset of them (leading zeros dropped), over up to 200 test cases.	Medium5	BacktrackingCombinatorics+1	No attempts yet	1.5s	128 MB	Judgeable
Simple PolygonOrder given points into a specific simple polygon by picking a bottom-most anchor and sorting the rest by polar angle with a special tie-break for collinear groups.	Medium5	GeometrySorting+1	No attempts yet	1s	128 MB	Judgeable
ContainerGiven n containers stackable 5-high, find the rectangular grid of stacks (with fixed spacing rules) minimizing area then minimizing the length-width gap.	Medium5	MathBrute force+1	No attempts yet	1s	128 MB	Judgeable
PieGiven N cylindrical pies, find the maximum piece volume so that F+1 equal-sized pieces can be cut from the pies, using binary search on the answer.	Medium5	Binary searchMath+1	No attempts yet	1s	128 MB	Judgeable
JBCGiven a custom digit ordering and numbers written in it, sum the decimal value of each number over every valid base from 2 up to the digit count.	Medium5	MathString+1	No attempts yet	1s	128 MB	Judgeable
HighwayGiven villages near a segment highway, find the minimum number of points on the segment so every village lies within distance D of some chosen point.	Medium5	GreedyGeometry+1	No attempts yet	1s	128 MB	Judgeable
ComputersGiven a fixed replacement cost and arbitrary maintenance costs for owning a computer over any year range, find the minimum total cost to cover n years using dynamic programming.	Medium5	Dynamic programmingArray	No attempts yet	1s	128 MB	Judgeable
The Stable Marriage ProblemGiven male and female preference lists, compute and output the male-optimal stable matching using the Gale-Shapley algorithm.	Medium5	GreedySimulation+1	No attempts yet	1s	128 MB	Judgeable
Arne SaknussemmReverse a described scrambling procedure that pads, reverses, and writes a message column by column into a table, given its row fragments, to recover the original text.	Medium5	StringSimulation+1	No attempts yet	1s	128 MB	Judgeable
Linear WorldSimulate 1D walkers who reverse on collision (equivalent to pass-through) and find the last one to fall off an edge and its time.	Medium5	SimulationGreedy+1	No attempts yet	1s	128 MB	Judgeable
Network ConnectionSimulate weighted union operations that always merge into the second cluster's center, and answer path-length queries to the current cluster center.	Medium5	Union-findImplementation+1	No attempts yet	1s	128 MB	Judgeable
How do spiders walk on water?Given water speeds up to a waterfall (possibly following a linear recurrence and needing extrapolation), determine the closest safe distance a spider can reach or print a special fall message.	Medium5	MathSimulation+1	No attempts yet	1s	128 MB	Judgeable
Distributing Ballot BoxesGiven city populations and a fixed total number of ballot boxes (each city gets at least one), find the assignment minimizing the maximum people per box, via binary search over the answer.	Medium5	Binary searchGreedy	No attempts yet	3s	128 MB	Judgeable
Game, Set and MatchGiven the per-point win probability p, compute the probabilities of winning a tennis game, set, and match using the standard scoring rules.	Medium5	Dynamic programmingProbability+2	No attempts yet	1s	128 MB	Judgeable
Non-negative Partial SumsGiven a cyclic array, count how many rotations make every prefix sum of the rotated sequence non-negative.	Medium5	Prefix sumArray	No attempts yet	3s	128 MB	Judgeable
3-Sided DiceDetermine whether a target 3-outcome probability vector lies in the convex hull (with strictly positive weights) of three given dice's probability vectors.	Medium5	GeometryMath+1	No attempts yet	1s	128 MB	Judgeable
Minimal BackgammonSimulate turn by turn probability mass over board positions (with lose-a-turn and go-to-start squares, and bounce-back overshoot rule) to find probability of reaching the goal within T turns.	Medium5	Dynamic programmingSimulation+1	No attempts yet	1s	128 MB	Judgeable
Bug HuntSimulate a small array based language line by line and report the first line where an out of range index or an unassigned array element is used.	Medium5	SimulationImplementation+1	No attempts yet	1s	128 MB	Judgeable
Sum of Distinct PrimesCount subsets of k distinct primes summing to n, using dynamic programming over sieve-generated primes up to 1120.	Medium5	Dynamic programmingMath+1	No attempts yet	1s	128 MB	Judgeable
Maximum SumGiven n boxes of numbered balls, pick at most one ball per box in order to form a non-decreasing sequence with maximum possible sum.	Medium5	Dynamic programmingSorting	No attempts yet	1s	128 MB	Judgeable
Pathological PathsGiven a set of file paths defining a directory tree, resolve query paths (with '.', '..', and index.html shortcuts) and decide if two paths refer to the same existing file.	Medium5	StringHash map+2	No attempts yet	1s	128 MB	Judgeable
Area of PolygonsGiven a simple integer-coordinate polygon, count how many unit grid squares have nonzero area of intersection with it.	Medium5	GeometrySimulation+1	No attempts yet	1s	128 MB	Judgeable
Faulhaber's TriangleBuild Faulhaber's triangle row by row using the recurrence F(i,j)=i/j*F(i-1,j-1) plus the normalization that each row sums to 1, then answer queries for F(m,k) as reduced fractions.	Medium5	Dynamic programmingMath+1	No attempts yet	1s	128 MB	Judgeable
Windmill AnimationSimulate a line rotating counter-clockwise about a pivot point, switching pivot whenever the line hits another of the given points, and report the first S pivots. Repeat for each dataset.	Medium5	GeometrySimulation+2	No attempts yet	1s	128 MB	Judgeable
Candy DistributionFor each pair K and C, find the smallest B up to 1e9 with BC = KX + 1 for some positive integer X, or report IMPOSSIBLE.	Medium5	Number theoryMath+2	No attempts yet	1s	128 MB	Judgeable
Factorials and PowersFor each pair n and k, find the largest i such that n! is divisible by k^i.	Medium5	Number theoryMath	No attempts yet	1s	128 MB	Judgeable
Router Placement to Minimize Maximum TTLGiven a tree, pick the vertex that minimizes the largest distance to any other vertex, and output that minimum maximum distance (the tree's radius).	Medium5	TreeGraph+2	No attempts yet	1s	128 MB	Judgeable
CounterattackTwo strikers advance in lockstep through n points, each step either dribbling or passing to the partner; find the cheapest route from a long pass at point 1 to a shot at point n.	Medium5	Dynamic programmingArray+1	No attempts yet	1s	256 MB	Judgeable
Soccer Bets16 shuffled match results with scores are given; reconstruct the single-elimination bracket and report the tournament winner.	Medium5	GraphImplementation+2	No attempts yet	1s	128 MB	Judgeable
Good WordsA word of A's and B's is good when its letters can be paired by equal letters with non-crossing arcs; count how many of the given words are good.	Medium5	StackString+2	No attempts yet	1s	256 MB	Judgeable
Voyager 1From a starting cell, fire a beam in each of four directions through mirrors / and \, black holes C, and empty cells, and report which direction survives longest or detect an infinite loop.	Medium5	SimulationImplementation+2	No attempts yet	1s	128 MB	Judgeable
I've Got Your Back(gammon)Map between 6-tuples of 15 pieces on 6 points, ordered lexicographically, and their index among the 15504 configurations.	Medium5	CombinatoricsMath+2	No attempts yet	1s	128 MB	Judgeable
Pool BallsCount squares v with a < v < b whose predecessor v-1 is a triangular number, over several test cases.	Medium5	MathNumber theory+2	No attempts yet	1s	128 MB	Judgeable
Pro-Test VotingGiven a budget and precincts whose vote gain follows a concave spending curve, allocate dollars to maximize rounded total votes, breaking ties toward lower-numbered precincts.	Medium5	Dynamic programmingGreedy	No attempts yet	1s	128 MB	Judgeable
FlipperSimulate two-ended pile flips on a row of cards, then report the card number and orientation at queried positions.	Medium5	SimulationImplementation+1	No attempts yet	1s	128 MB	Judgeable
Emma Loves PartiesGiven parties as hourly intervals, find the most Emma can attend if she stays at least 30 minutes at each one.	Medium5	GreedySorting+1	No attempts yet	1s	128 MB	Judgeable
SudokuFill the five empty cells (marked 0) in a 9x9 Sudoku grid so every row, column, and 3x3 box contains the digits 1 through 9 exactly once.	Medium5	BacktrackingImplementation+2	No attempts yet	1s	128 MB	Judgeable
Lemmings, Lemmings Everywhere. But Not For Long.Given a grid where every cell holds a lemming with a cyclic four-direction agenda, simulate their simultaneous movement and report how many steps until all lemmings exit the board.	Medium5	SimulationImplementation+1	No attempts yet	1s	128 MB	Judgeable
Once Around the LockGiven a circular dial and a code, decide whether a sequence of clockwise and counterclockwise turns unlocks the lock.	Medium5	SimulationImplementation	No attempts yet	1s	128 MB	Judgeable
And Now, a Remainder from Our SponsorDecode message groups given four pairwise coprime keys by solving each group as a system of remainders, then map numbers back to letters.	Medium5	Number theoryMath+1	No attempts yet	1s	128 MB	Judgeable
CaterpillarGiven up to 100 nodes, decide whether the graph is a connected tree whose every node lies on or adjacent to some single path.	Medium5	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
Folding GameFor each fold sequence on a rectangle, count how many paper layers sit under a given point.	Medium5	SimulationImplementation+2	No attempts yet	1s	128 MB	Judgeable
BalloonsAllocate balloons from two rooms to teams with given distances so total delivery distance is minimized.	Medium5	GreedySorting	No attempts yet	1s	128 MB	Judgeable
Largest SquareGiven a 0/1 matrix, find the side length of the largest all-ones square submatrix.	Medium5	Dynamic programmingMatrix	No attempts yet	5s	256 MB	Judgeable
PalindrometerGiven an odometer reading with fixed digit positions, find the smallest number of kilometers to drive until it reads as a palindrome, counting leading zeros.	Medium5	StringMath+2	No attempts yet	1s	128 MB	Judgeable
SkylineCount permutations of 1..N with no increasing subsequence of length 3, modulo 1,000,000, for each N up to 1,000.	Medium5	Dynamic programmingCombinatorics+1	No attempts yet	1s	128 MB	Judgeable
Underground CablesGiven up to 1000 points in the plane, find the minimum total length of non-crossing straight cables that connect all points.	Medium5	Minimum spanning treeGraph+1	No attempts yet	1s	128 MB	Judgeable
Block GameGiven a 6x6 sliding block board and a special 1x2 piece, find the minimum number of slides to move it out through a gap on the right.	Medium5	BFSSimulation+1	No attempts yet	10s	128 MB	Judgeable
A No-Win SituationGiven a deck, decide whether some number of draws lets the player beat the dealer in a simplified Blackjack.	Medium5	SimulationImplementation+1	No attempts yet	1s	128 MB	Judgeable
MeganominoesFor each query i, count unordered pairs of distinct tiles where one matching pair of ends touches and the two opposite ends sum to i.	Medium5	Hash mapBrute force+1	No attempts yet	1s	128 MB	Judgeable
Buying GasChoose the fewest gas stations to stop at so the car never runs out of gas over a trip of length d with tank range 10n.	Medium5	GreedySorting+1	No attempts yet	1s	128 MB	Judgeable
The Next PrimeFor each of several integers n, print the smallest prime number greater than or equal to n.	Medium5	Number theoryMath	No attempts yet	1s	128 MB	Judgeable
Bridges and TunnelsAfter each new edge between two named buildings, print the size of the connected component that the edge joins.	Medium5	Union-findHash map+2	No attempts yet	3s	128 MB	Judgeable
BuzzwordsFor each line, strip spaces and report the highest occurrence count among substrings of length 1, 2, 3, and so on, stopping at the first length where no substring repeats.	Medium5	StringHash map+2	No attempts yet	1s	128 MB	Judgeable
Ferry Loading VGiven distinct vehicle weights, split them between two lanes so the totals differ as little as possible. Output the minimum difference.	Medium5	Dynamic programmingPrefix sum+1	No attempts yet	1s	128 MB	Judgeable
Frosh WeekGiven n distinct student numbers in a line, find the minimum number of adjacent swaps needed to sort them into increasing order.	Medium5	SortingDivide and conquer+2	No attempts yet	1s	128 MB	Judgeable
Cantor SetGiven a decimal x between 0 and 1 that ends within 6 fractional digits, decide whether x lies in the Cantor set, that is, whether some ternary expansion of x avoids the digit 1.	Medium5	MathNumber theory+2	No attempts yet	1s	128 MB	Judgeable
Scrolling SignGiven k-wide words, find the minimum total letters scrolled in so that each word appears in order, allowing overlap between consecutive words.	Medium5	Dynamic programmingString+2	No attempts yet	1s	128 MB	Judgeable
Logo 2One numeric argument in a turtle graphics program is missing; find the value that makes the turtle return to its starting point.	Medium5	GeometryMath+2	No attempts yet	1s	128 MB	Judgeable
Curvy Little BottlesGiven a polynomial and x bounds that define a bottle of revolution, find the x positions where the cumulative volume hits each increment, up to 8 marks.	Medium5	MathBinary search+2	No attempts yet	1s	128 MB	Judgeable
Ancient HieroglyphsDecode a hex bitmap, count enclosed white regions (holes) inside each connected black shape, and map each shape's hole count to a hieroglyph code.	Medium5	GraphDFS+2	No attempts yet	1s	192 MB	Judgeable
Open SourceCount distinct students per project, drop any student who signed up for more than one project, then sort projects by count descending and name.	Medium5	Hash mapSorting+2	No attempts yet	1s	128 MB	Judgeable
Tour de FranceGiven front and rear sprocket tooth counts, find the maximum ratio between adjacent attainable drive ratios n/m across all pairs.	Medium5	SortingMath+2	No attempts yet	1s	128 MB	Judgeable
Team RankingsGiven up to 100 rankings of five teams, find the ranking minimizing the sum of pairwise-order disagreements, breaking ties alphabetically.	Medium5	Brute forceCombinatorics+2	No attempts yet	1s	128 MB	Judgeable
Chat RoomsFor each submitted line, decide accept or reject using consonant-run length, the count of recent suspicious lines, and recent duplicate counts over a sliding window of the last 10 lines.	Medium5	Sliding windowString+2	No attempts yet	1s	128 MB	Judgeable
Hermes' ColonyFor each province of 3 or 4 planar points, compute the length of the minimum Steiner tree connecting the cities, allowing extra junction points.	Medium5	GeometryMath+2	No attempts yet	1s	128 MB	Judgeable
Ball TossSimulate a ball toss game where each catcher flips her left/right direction and throws relative to the previous thrower, and report the last student touched.	Medium5	SimulationImplementation	No attempts yet	1s	128 MB	Judgeable
Plugged InGiven pin-to-hole connections on an n x n grid, find the socket orientation (rotations and flips) minimizing the average Manhattan wire length.	Medium5	ImplementationMath+1	No attempts yet	1s	128 MB	Judgeable
Flipping ColorsRepeatedly split each rectangle in fixed ratios h:v and flip the colors of the upper-right and lower-left parts; report the color reached by each query point.	Medium5	RecursionDivide and conquer+2	No attempts yet	1s	128 MB	Judgeable
War on WeatherCount how many surface targets have at least one satellite with a clear line of sight that does not pass through the Earth.	Medium5	GeometryMath+2	No attempts yet	1s	128 MB	Judgeable
Factstone BenchmarkFor each year, compute the word size by doubling every decade from 4 bits in 1960, then find the largest n with n! <= 2^b - 1.	Medium5	MathBinary search+2	No attempts yet	1s	128 MB	Judgeable
Bungee JumpingGiven rope stiffness k, rest length l, bridge height s, and weight w, decide whether Bond gets stuck in the air, dies on impact, or lands safely using energy conservation. Multiple test cases until four zeros.	Medium5	MathSimulation+1	No attempts yet	1s	128 MB	Judgeable
Catamaran BallastSplit the given rock weights between two hulls so the difference of the two sums is as small as possible.	Medium5	Dynamic programmingBrute force	No attempts yet	1s	128 MB	Judgeable
Evil Straw Warts LiveFor each string, find the fewest adjacent swaps needed to rearrange it into a palindrome, or report that no palindrome is possible.	Medium5	GreedyTwo pointers+2	No attempts yet	1s	128 MB	Judgeable
Perfect P-th PowerFor each nonzero integer x, find the largest exponent p such that x equals some integer raised to the p-th power.	Medium5	Number theoryMath+1	No attempts yet	1s	128 MB	Judgeable
Calories from FatGiven food lines listing fat, protein, sugar, starch, and alcohol in grams, Calories, or percent, compute the percent of total Calories from fat.	Medium5	MathImplementation+1	No attempts yet	1s	128 MB	Judgeable
Genealogical ResearchProcess birth and death records, then answer ancestor and descendant queries by printing the family tree recursively with dates.	Medium5	RecursionTree+2	No attempts yet	1s	128 MB	Judgeable
Treasure MapGiven a step list and a magnetic declination, rotate every heading and find the minimum distance between the two resulting polylines.	Medium5	GeometryImplementation+2	No attempts yet	1s	128 MB	Judgeable
Ferry Loading IIGiven car arrival times, ferry capacity n, and one-way time t, find the earliest finish time and the fewest one-way crossings to move all cars.	Medium5	GreedyImplementation+2	No attempts yet	1s	128 MB	Judgeable