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Total results3,610 problems

Word Search
Medium5
Trie, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Concert Rest Schedule
Medium5
Greedy, Intervals+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Counting Axis-Aligned Right Triangles
Medium5
Hash map, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tennis
Medium5
Simulation, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Non-Intersecting Circles
Medium5
Greedy, Intervals+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Beacon Network
Medium5
Simulation, Heap+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sangbeom's Secret Message
Medium5
String, Brute force+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sidewalk Pillars
Medium5
Greedy, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tomo's Calculator
Medium5
Math, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cinema Invitation
Medium5
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Restoring a Scrambled Email
Medium5
String, Brute force+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
JANICA
Medium5
Simulation, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tram
Medium5
Shortest path, Graph+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
21 Rolls of Gimbap
Medium5
Simulation, Matrix+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Airplane
Medium5
Simulation, Queue+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Foot Typing
Medium5
Dynamic programming, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cards
Medium5
Simulation, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
T9
Medium5
String, Hash map+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Popularity List
Medium5
Greedy, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
PIN
Medium5
Hash map, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Matching Bins
Medium5
Binary search, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Coin
Medium5
Brute force, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Linker
Medium5
Graph, BFS+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Gems
Medium5
Tree, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Play on Words
Medium5
Graph, Union-find+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Kingdom Roadmap
Medium5
Tree, Graph+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Database
Medium5
Brute force, Hash map+1
No attempts yet
Time limit
1s
Memory limit
128 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
Drying
Medium5
Binary search, Greedy
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
L Puzzle
Medium5
Greedy, Simulation+1
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
The Stable Marriage Problem
Medium5
Greedy, Simulation+1
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
Voyager 1
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
Palindrometer
Medium5
String, Math+2
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
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
Logo 2
Medium5
Geometry, 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
Bungee Jumping
Medium5
Math, Simulation+1
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
Ferry Loading II
Medium5
Greedy, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Coprime
Medium5
Number theory, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Multiplication Game
Medium5
Game theory, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
A Multiple Made Only of Ones
Medium5
Number theory, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tight Words
Medium5
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Splitting Teams Fairly
Medium5
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Building the Constellation
Medium5
Minimum spanning tree, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Games R Us
Medium5
Hash map, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Frenemies
Medium5
DFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Extent of the Problem
Medium5
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Blue Jeans
Medium5
String, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Typesetting
Medium5
Simulation, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Rock Skipping
Medium5
Brute force, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Overflowing Bookshelf
Medium5
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Safecracker
Medium5
Brute force, Backtracking+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sum It Up
Medium5
Backtracking, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Another Puzzling Problem
Medium5
Implementation, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Mark-up Processor
Medium5
String, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Turn of the Shrew
Medium5
Bit manipulation, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Reverse Roman Notation
Medium5
Implementation, Stack+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The End of the World
Medium5
Recursion, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Juggler
Medium5
Implementation, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Trees
Medium5
Graph, Union-find+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Railroad
Medium5
Dynamic programming, Two pointers+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Shuffling
Medium5
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
PERMS
Medium5
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sum of Squared Digits
Medium5
Hash map, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Analyzing Login/Logout Records
Medium5
Intervals, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Horror List
Medium5
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Robots on a Grid
Medium5
Dynamic programming, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
ls
Medium5
Dynamic programming, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Royal Succession
Medium5
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Playfair Cipher
Medium5
Simulation, Matrix+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Shopaholic
Medium5
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Constellations
Medium5
Graph, Union-find+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Image Segmentation
Medium5
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bat Positioning
Medium5
Geometry, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Road Trip
Medium5
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Rig Placement
Medium5
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Overlap!
Medium5
Implementation, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Study Days
Medium5
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Yes or No?
Medium5
Dynamic programming, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Throw a Party!!!
Medium5
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Biomedical Engineering
Medium5
Dynamic programming, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Gerrymandering
Medium5
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
And the Winner Is
Medium5
Implementation, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Soccer
Medium5
Probability, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Battleground Preservation
Medium5
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Life Connections
Medium5
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pirates' Path
Medium5
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Decimal to Fraction
Medium5
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Jumbled Letters
Medium5
String, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bad Wiring
Medium5
Greedy, Bit manipulation
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Word SearchGiven N database words compared in order against a query using character-by-character matching that also checks for word-end, compute total comparisons per query.	Medium5	TrieString+1	No attempts yet	1s	128 MB	Judgeable
Concert Rest ScheduleSchedule N members' fixed-length rest intervals within a T-minute concert so that at most two intervals overlap at any moment.	Medium5	GreedyIntervals+1	No attempts yet	1s	128 MB	Judgeable
Counting Axis-Aligned Right TrianglesCount triangles among N points where the right angle vertex has one point sharing its x-coordinate and another sharing its y-coordinate.	Medium5	Hash mapMath+1	No attempts yet	1s	128 MB	Judgeable
TennisValidate whether recorded tennis set scores form a legal best-of-three match, with a special rule that one named player never loses a set.	Medium5	SimulationImplementation+1	No attempts yet	1s	128 MB	Judgeable
Non-Intersecting CirclesGiven N circles centered on the x-axis, find the minimum number to remove so no two remaining circles overlap, essentially an interval scheduling problem.	Medium5	GreedyIntervals+1	No attempts yet	1s	128 MB	Judgeable
Beacon NetworkSimulate beacons that light up over time and archers who shoot arrows down a fixed priority list toward unlit targets, computing each beacon's lighting time.	Medium5	SimulationHeap+1	No attempts yet	1s	128 MB	Judgeable
Sangbeom's Secret MessageGiven a Vigenere-style encrypted message and a known substring of the plaintext, deduce the repeating key and decrypt the full message.	Medium5	StringBrute force+1	No attempts yet	1s	128 MB	Judgeable
Sidewalk PillarsGiven a sidewalk string and up to N extra pillars, place pillars in free segments to minimize the count of length-L parking spots, breaking ties by using fewest pillars.	Medium5	GreedyString+1	No attempts yet	1s	128 MB	Judgeable
Tomo's CalculatorGiven a calculator that repeatedly multiplies by B starting from A*B, find how many presses of '=' are needed until the displayed number ends with a given suffix C, or report impossible.	Medium5	MathSimulation+1	No attempts yet	1s	128 MB	Judgeable
Cinema InvitationGiven each friend's minimum required number of other attending friends, find the smallest subset size satisfying everyone invited's threshold.	Medium5	GreedySorting+1	No attempts yet	1s	128 MB	Judgeable
Restoring a Scrambled EmailGiven a scrambled string formed by replacing '@' with 'at' and optionally inserting 'nospam' once, output all distinct valid email addresses that could produce it.	Medium5	StringBrute force+1	No attempts yet	1s	128 MB	Judgeable
JANICAReconstruct running leader times from cumulative differences over two ski rounds to find the top three finishers by total time.	Medium5	SimulationSorting+1	No attempts yet	1s	128 MB	Judgeable
TramFind the minimum number of switch changes needed to travel from intersection A to B in a directed graph where each node's first listed edge is free and others cost 1, using shortest-path with 0/1 edge weights.	Medium5	Shortest pathGraph+1	No attempts yet	1s	128 MB	Judgeable
21 Rolls of GimbapSimulate a Connect Four style game on a 6x7 board from 21 alternating moves and report who first got four in a row and on which of their throws.	Medium5	SimulationMatrix+1	No attempts yet	1s	128 MB	Judgeable
AirplaneSimulate passengers walking down a single aisle to their assigned row and taking 5 seconds to load luggage, blocked by others ahead, to find total boarding time.	Medium5	SimulationQueue+1	No attempts yet	1s	128 MB	Judgeable
Foot TypingGiven two words and their interleaving, output the lexicographically smallest sequence of 1s and 2s marking which word produced each character.	Medium5	Dynamic programmingString+1	No attempts yet	1s	128 MB	Judgeable
CardsSimulate a card-sorting game to find which numbers remain consistent with a sequence of column answers after repeated row/column reshuffling.	Medium5	SimulationMath	No attempts yet	1s	128 MB	Judgeable
T9Simulate a T9 keypad predictor that maps key-press sequences to dictionary words, splitting on key 1 as space and marking unmatched words with asterisks.	Medium5	StringHash map+1	No attempts yet	1s	128 MB	Judgeable
Popularity ListReconstruct the lexicographically smallest previous week's ranking consistent with UP/DOWN/SAME movement marks of this week's list.	Medium5	GreedyArray+1	No attempts yet	1s	128 MB	Judgeable
PINCount pairs of 4-character PINs (from a given list) that differ in exactly D of their four positions.	Medium5	Hash mapCombinatorics+1	No attempts yet	1s	128 MB	Judgeable
Matching BinsGiven a sequence of bin sizes, find the largest K such that the first K bins can each be matched to a distinct larger bin among the following K bins.	Medium5	Binary searchGreedy+1	No attempts yet	1s	128 MB	Judgeable
CoinDetermine the fake coin among 12 and whether it is heavier or lighter, given three balance weighing results, or report impossible/indefinite.	Medium5	Brute forceSimulation+1	No attempts yet	1s	128 MB	Judgeable
LinkerGiven modules with export/import tables and an entry symbol, find the reachable non-redundant modules, duplicate exports used by them, and unresolved imports.	Medium5	GraphBFS+1	No attempts yet	1s	128 MB	Judgeable
GemsGiven a tree, assign positive integer prices to vertices so adjacent vertices differ, minimizing total sum, essentially a greedy coloring based on tree structure.	Medium5	TreeGreedy+1	No attempts yet	1s	128 MB	Judgeable
Play on WordsDetermine whether all given words can be chained into one sequence where each word's first letter matches the previous word's last letter, using Eulerian path conditions on a letter graph.	Medium5	GraphUnion-find+1	No attempts yet	1s	256 MB	Judgeable
Kingdom RoadmapGiven a tree, compute the minimum number of extra edges needed so the graph stays connected after any single edge removal, which equals the number of leaves divided by two, rounded up.	Medium5	TreeGraph+1	No attempts yet	2s	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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
CoprimeFor each n up to 1e9, count how many positive integers less than n share no common factor with n, handling several test cases until a 0.	Medium5	Number theoryMath+1	No attempts yet	1s	128 MB	Judgeable
Multiplication GameAlice and Bob multiply a running product by 2 to 9 in turn; find who forces the product to reach n first with optimal play.	Medium5	Game theoryDynamic programming+1	No attempts yet	1s	128 MB	Judgeable
A Multiple Made Only of OnesGiven n not divisible by 2 or 5, find the number of digits of the smallest repunit (all ones) that n divides.	Medium5	Number theoryMath+2	No attempts yet	1s	128 MB	Judgeable
Tight WordsCount words of length n over digits 0..k where adjacent digits differ by at most 1, then print that count as a percentage rounded to five decimals.	Medium5	Dynamic programmingCombinatorics+2	No attempts yet	1s	128 MB	Judgeable
Splitting Teams FairlySplit N people into two teams differing in size by at most one so their total weight difference is minimized, then print both totals in increasing order.	Medium5	Dynamic programmingArray+2	No attempts yet	1s	128 MB	Judgeable
Building the ConstellationGiven n points in the plane, connect all of them with straight segments of Euclidean length so the total cost is minimized.	Medium5	Minimum spanning treeGraph+2	No attempts yet	1s	128 MB	Judgeable
Games R UsGroup users into equivalence classes by identical directory access sets, then report classes of size 2 or more.	Medium5	Hash mapSorting+2	No attempts yet	1s	128 MB	Judgeable
FrenemiesFor each dataset, sum the signed scores of all simple paths without neutral links between a given person and every other person.	Medium5	DFSGraph+2	No attempts yet	1s	128 MB	Judgeable
The Extent of the ProblemSimulate RADDD's two-step defragmentation passes over disk blocks and output the final extent layout of every file.	Medium5	SimulationImplementation+2	No attempts yet	1s	128 MB	Judgeable
Blue JeansGiven up to 10 DNA strings of length 60, find the longest substring that appears in all of them, breaking ties alphabetically, or report none of length 3 or more.	Medium5	StringBrute force+2	No attempts yet	1s	128 MB	Judgeable
TypesettingPack bitmap glyphs as tightly as possible so no visible pixels from different glyphs touch horizontally, then print the result.	Medium5	SimulationImplementation	No attempts yet	1s	128 MB	Judgeable
Rock SkippingFor each lake map, find the throw (start, skip distance) that maximizes count, then length, then start, then smallest distance, and print it.	Medium5	Brute forceImplementation+2	No attempts yet	1s	128 MB	Judgeable
Overflowing BookshelfSimulate a fixed-width shelf through add (push books leftward) and remove events; at End list the surviving books left to right.	Medium5	SimulationImplementation+2	No attempts yet	1s	128 MB	Judgeable
SafecrackerGiven a target T and up to 12 distinct uppercase letters, find five distinct letters whose signed power sum equals T; if several work, print the lexicographically greatest string.	Medium5	Brute forceBacktracking+2	No attempts yet	1s	128 MB	Judgeable
Sum It UpGiven a target and up to 12 numbers, list every distinct subset sum equal to the target, sorted in decreasing lexicographic order.	Medium5	BacktrackingSorting+2	No attempts yet	1s	128 MB	Judgeable
Another Puzzling ProblemEach jigsaw piece carries four integer edge labels; match opposite labels to place every piece in the N by N grid, then print the assembled picture.	Medium5	ImplementationBrute force+2	No attempts yet	1s	128 MB	Judgeable
Mark-up ProcessorStrip a small mark-up language from text: handle bold, italic, size, and a toggle that turns processing off, printing only the plain characters.	Medium5	StringSimulation+2	No attempts yet	1s	128 MB	Judgeable
The Turn of the ShrewEach child's code must differ from the bitwise OR of some male and female adult code; find the minimum Hamming distance over all pairs.	Medium5	Bit manipulationBrute force+2	No attempts yet	1s	128 MB	Judgeable
Reverse Roman NotationSimulate a stack calculator where operands are Roman numerals; parse and print them, and handle underflow, division by zero, and out-of-range errors.	Medium5	ImplementationStack+2	No attempts yet	1s	128 MB	Judgeable
The End of the WorldGiven a valid intermediate state of the Towers of Hanoi, compute how many more moves remain in the optimal solution.	Medium5	RecursionDivide and conquer+2	No attempts yet	1s	128 MB	Judgeable
JugglerBalls sit in a circle with one in hand; rotate either way or drop the held ball, which brings its clockwise neighbor into hand. Find the fewest moves to drop all balls in a given order.	Medium5	ImplementationSimulation+2	No attempts yet	1s	128 MB	Judgeable
TreesGiven an undirected graph, count its connected components that contain no cycle and report the count per test case.	Medium5	GraphUnion-find+2	No attempts yet	1s	256 MB	Judgeable
RailroadGiven two sequences, decide whether a target sequence can be formed by repeatedly taking the front car of either train; once one train empties, the rest follow in order.	Medium5	Dynamic programmingTwo pointers+2	No attempts yet	1s	128 MB	Judgeable
ShufflingGiven a fixed permutation of N cards and a target order, find the minimum number of times to apply the permutation to reach the target, or -1 if impossible.	Medium5	MathNumber theory+2	No attempts yet	1s	128 MB	Judgeable
PERMSFor each query (n, k), count permutations of 1..n having exactly k inversions, with n up to 18 and k up to 200.	Medium5	Dynamic programmingCombinatorics+2	No attempts yet	1s	128 MB	Judgeable
Sum of Squared DigitsFor two starting numbers, follow the sum-of-squared-digits map and report the smallest total length until a value appears in both sequences, or 0 if they never meet.	Medium5	Hash mapSimulation+2	No attempts yet	1s	128 MB	Judgeable
Analyzing Login/Logout RecordsGiven login and logout records on PCs, compute for each query how many minutes a student used at least one PC during a time interval.	Medium5	IntervalsSimulation+2	No attempts yet	1s	128 MB	Judgeable
Horror ListEach movie gets a level: 0 if on the horror list, else one plus the best level among similar movies; output the movie with the highest finite level, breaking ties by smallest ID.	Medium5	GraphBFS+2	No attempts yet	1s	128 MB	Judgeable
Robots on a GridCount monotone right/down paths from the top-left to the bottom-right of an n by n grid with blocked cells, modulo 2^31-1, and report whether the goal is reachable at all, or reachable only with up and left moves allowed.	Medium5	Dynamic programmingDFS+2	No attempts yet	1s	128 MB	Judgeable
lsGiven a wildcard pattern where * matches any run of characters, print the input file names that match it, keeping input order.	Medium5	Dynamic programmingString+2	No attempts yet	1s	128 MB	Judgeable
Royal SuccessionGiven parent pairs for N people, compute each claimant's inherited fraction of the founder's blood and print the claimant with the largest fraction.	Medium5	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
Playfair CipherBuild a 5x5 Playfair key table from a key phrase, split the plaintext into digraphs with X padding, and apply the row, column, or rectangle substitution rules. Output the uppercase ciphertext.	Medium5	SimulationMatrix+2	No attempts yet	1s	128 MB	Judgeable
ShopaholicGiven item prices, group them into triples so that the cheapest item in each triple is free, and maximize the total discount.	Medium5	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
ConstellationsGiven up to 500 star coordinates, connect each star to its nearest neighbor(s) and count the connected components of the resulting graph.	Medium5	GraphUnion-find+2	No attempts yet	1s	128 MB	Judgeable
Image SegmentationGiven an H by W color image, band each RGB value by dividing by S, then count 8-connected regions of equal band triples whose pixel size is at least L.	Medium5	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
Bat PositioningFind the point that equals the centroid of exactly the pointers lying at least 100 units away from it, rounding coordinates to the nearest integer.	Medium5	GeometryImplementation+2	No attempts yet	1s	128 MB	Judgeable
Road TripGiven a weighted tree rooted at city 1, remove exactly one non-root vertex so the round trip from city 1 covering all remaining cities is shortest, and report that length.	Medium5	TreeDFS+2	No attempts yet	1s	128 MB	Judgeable
Rig PlacementGiven n oil fields, a per-field investment cap m, and a total budget B, pick an investment amount for each field so total oil is maximized.	Medium5	Dynamic programmingArray+2	No attempts yet	1s	128 MB	Judgeable
Overlap!Given each course's exam day and time slot and each student's course list, count students who have two or more finals that overlap in time.	Medium5	ImplementationSorting+2	No attempts yet	1s	128 MB	Judgeable
Study DaysDistribute H study hours among n courses, each with 10 grade thresholds, to maximize the average grade point, rounded to two decimals.	Medium5	Dynamic programmingArray+2	No attempts yet	1s	128 MB	Judgeable
Yes or No?Pick between l and r questions to answer Yes, maximizing the sum of per-question expected correct probabilities, and report the maximum expectation to two decimals.	Medium5	Dynamic programmingSorting+2	No attempts yet	1s	128 MB	Judgeable
Throw a Party!!!Given friends' home regions with drunk/sober status and cars with capacity bound to regions, compute how many friends cannot be seated (each car needs a sober driver).	Medium5	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
Biomedical EngineeringGiven a target string and a set of reusable component strings, find the minimum number of components whose concatenation equals the target, or report that it is impossible.	Medium5	Dynamic programmingString+2	No attempts yet	1s	128 MB	Judgeable
GerrymanderingSplit n precincts, each with P and Q vote counts, into two nonempty districts; find how many districts P can win (0, 1, or 2).	Medium5	Dynamic programmingArray+2	No attempts yet	1s	128 MB	Judgeable
And the Winner IsEach ballot has one character per candidate; discard any ballot that marks more than one candidate in the same race, then report the top vote-getter (ties included) in every race, in input order.	Medium5	ImplementationArray+2	No attempts yet	1s	128 MB	Judgeable
SoccerCompute probability distribution of final scores after up to T seconds of a stochastic soccer simulation with passing, stealing, shooting, and absorbing states.	Medium5	ProbabilityDynamic programming+2	No attempts yet	2s	128 MB	Judgeable
Battleground PreservationGiven past battle results with costs, find the cheapest chain of victories between two fighters and decide the winner, or output FIGHT! if neither dominates.	Medium5	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
Life ConnectionsGiven an undirected friendship graph, count the distinct shortest paths between each queried pair of nodes, where path length counts nodes.	Medium5	GraphBFS+2	No attempts yet	1s	128 MB	Judgeable
Pirates' PathFind the path from s to e in an undirected graph that uses the fewest guarded edges, where each edge has cost 0 or 1.	Medium5	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
Decimal to FractionConvert a decimal string, with an optional repeating block in parentheses, into the exact fraction in lowest terms.	Medium5	MathNumber theory+2	No attempts yet	1s	128 MB	Judgeable
Jumbled LettersFor each query, find the longest dictionary word that can be formed using the query letters at most once, breaking ties alphabetically, or report IMPOSSIBLE.	Medium5	StringHash map+2	No attempts yet	1s	128 MB	Judgeable
Bad WiringEach switch toggles a window of 2D+1 lights; find the fewest flips that turn every light off, or report impossibility.	Medium5	GreedyBit manipulation	No attempts yet	3s	128 MB	Judgeable