Problems

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Total results29,455 problems

String Construction
Medium5
Greedy, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Radar Installation
Medium5
Greedy, Intervals+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
String Construction 2
Medium5
Greedy, Two pointers+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Charm Bracelet
Medium5
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cow Contest
Medium5
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pearl Pairing
Medium5
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Loathesome Hay Baler
Medium5
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cow Travelling
Medium5
Dynamic programming, Matrix+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Munching
Medium5
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Cows on Skates
Medium5
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fence Repair
Medium5
Greedy, Heap+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Dream Counting
Medium5
Math, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tallest Cow
Medium5
Greedy, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Balanced Lineup
Medium5
Segment tree, Array
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Managing Allowance
Medium5
Binary search, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
ATM PIN Theft
Medium5
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hopeless Coach
Medium5
Dynamic programming, Probability+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Chessboard Dance
Medium5
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Crazy Search
Medium5
String, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Erdös Numbers
Medium5
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Prime Land
Medium5
Number theory, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
FORCAL
Medium5
String, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Packets
Medium5
Greedy, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Extended Lights Out
Medium5
Brute force, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Entropy
Medium5
Greedy, Heap+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Area
Medium5
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Gridland
Medium5
Math, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bit Maps
Medium5
Divide and conquer, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
String Computer
Medium5
Dynamic programming, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Coconuts: The Second Story
Medium5
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Nonstop Travel
Medium5
Simulation, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Stockbroker Grapevine
Medium5
Shortest path, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fact
Medium5
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Horseshoe Scoring
Medium5
Geometry, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Extrapolation Using a Difference Table
Medium5
Math, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hi-Q
Medium5
Simulation, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Call Forwarding
Medium5
Simulation, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Slurpys
Medium5
Recursion, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Power Shortage
Medium5
Minimum spanning tree, Graph+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Broken Keyboard
Medium5
Sliding window, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
El Dorado
Medium5
Dynamic programming, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
A Game with Marbles
Medium5
Dynamic programming, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Grocery store
Medium5
Brute force, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Automatic Typo Correction
Medium5
String, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Basic Wall Maze
Medium5
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Wine Trading in Gergovia
Medium5
Greedy, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
106 Miles to Chicago
Medium5
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
In Danger
Medium5
Math, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Assistance Required
Medium5
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Sierpinski Fractal
Medium5
Divide and conquer, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Code the Tree
Medium5
Tree, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Decode the Tree
Medium5
Tree, Heap+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Anagram Groups
Medium5
Hash map, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Equidistance
Medium5
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Counting Fibonacci Numbers
Medium5
Math, Binary search+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Bee Maja
Medium5
Math, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Quad Tree
Medium5
Recursion, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Friends
Medium5
String, Stack+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Team Queue
Medium5
Queue, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
France '98
Medium5
Dynamic programming, Probability+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Solving Linear Equations
Medium5
Math, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Eeny Meeny Moo
Medium5
Simulation, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Humble Numbers
Medium5
Dynamic programming, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Rhinoceros Beetle
Medium5
Implementation, Sorting+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Collatz Conjecture
Medium5
Simulation, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
String Encryption
Medium5
String, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
God Save the i-th Queen
Medium5
Array, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Clock Captcha
Medium5
Implementation, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Peculiar Primes
Medium5
Backtracking, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Railway Transportation
Medium5
Greedy, Binary search+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
C-Style Loops
Medium5
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Building a New Depot
Medium5
Geometry, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Storehouse
Medium5
Greedy, Hash map+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sea Battle
Medium5
Implementation, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Die Is Cast
Medium5
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Perfect Symmetry
Medium5
Hash map, Geometry+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Spiderman's Workout
Medium5
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tournament Ranking
Medium5
Graph, Topological sort+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Traffic Planning
Medium5
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Median Weight Bead
Medium5
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Choose Your Own Arithmetic
Medium5
Brute force, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Alice Through the Looking Glass
Medium5
Recursion, Divide and conquer+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Putnam Rank Range
Medium5
Math, Implementation
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Spies Like Us
Medium5
Graph, Hash map+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Barking Dogs!
Medium5
Simulation, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Shuffle
Medium5
Implementation, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Degrees of Separation
Medium5
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Nukit
Medium5
Game theory, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Twenty-four
Medium5
Brute force, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Moving Day
Medium5
Graph, Topological sort+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Snowflakes
Medium5
Hash map, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
CN Tower
Medium5
Sorting, Two pointers+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bananas
Medium5
String, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Quantum Operations
Medium5
Implementation, Matrix+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pinball Ranking
Medium5
Binary search, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Spreadsheet
Medium5
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Super Plumber
Medium5
Dynamic programming, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Scribble
Medium5
String, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Spam
Medium5
String, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cookies
Medium5
Geometry, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
String ConstructionRepeatedly take the leftmost or rightmost character of S and append it to T; among all such T, output the lexicographically smallest, wrapping lines at 80 characters.	Medium5	GreedyString+2	No attempts yet	1s	128 MB	Judgeable
Radar InstallationEach island on the sea side of a line must be covered by radars of reach d placed on the line, so find the minimum number of placements or report -1 if some island is unreachable.	Medium5	GreedyIntervals+2	No attempts yet	1s	128 MB	Judgeable
String Construction 2Build the lexicographically smallest string by repeatedly taking either the first or last character of the remaining string and appending it, with ties broken by comparing inward.	Medium5	GreedyTwo pointers+2	No attempts yet	1s	128 MB	Judgeable
Charm BraceletChoose a subset of N charms, each with a weight and a desirability, so that total weight stays within M and total desirability is maximized.	Medium5	Dynamic programmingArray+2	No attempts yet	1s	128 MB	Judgeable
Cow ContestGiven the winners of head-to-head matches, count how many cows have a skill rank that is fully forced by the results.	Medium5	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
Pearl PairingGiven counts of each pearl color, output the canonical pairing that matches the pearl at position i with the pearl at position i + N/2 in sorted order.	Medium5	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
The Loathesome Hay BalerRollers touch when center distance equals the sum of radii; find the path from the drive roller to the take-off roller and sum the absolute speeds, truncated.	Medium5	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
Cow TravellingCount the number of walks of exactly T steps on a grid from a start cell to a target cell, where each step moves to a vertically or horizontally adjacent open cell.	Medium5	Dynamic programmingMatrix+2	No attempts yet	1s	128 MB	Judgeable
MunchingFind the length of a shortest grid path from the cow to the barn through grass, then report the number of grass squares munched along it.	Medium5	BFSGraph+2	No attempts yet	1s	256 MB	Judgeable
Cows on SkatesFind a shortest orthogonal path from (1,1) to (R,C) through open grid cells, breaking ties by the lexicographically smallest sequence of cells.	Medium5	BFSGraph+2	No attempts yet	1s	128 MB	Judgeable
Fence RepairSplit one board into N planks of given lengths; each cut costs the length of the piece being cut, so find the minimum total cost.	Medium5	GreedyHeap+2	No attempts yet	1s	128 MB	Judgeable
Dream CountingCount how many times each decimal digit 0 through 9 appears when writing every integer from M to N.	Medium5	MathBrute force+2	No attempts yet	1s	128 MB	Judgeable
Tallest CowGiven the tallest cow's height and index plus pairs where cow a sees cow b, find each cow's maximum possible height consistent with all observations.	Medium5	GreedyPrefix sum+2	No attempts yet	1s	128 MB	Judgeable
Balanced LineupGiven a static array of cow heights, answer queries giving the max minus min over each range [A, B].	Medium5	Segment treeArray	No attempts yet	1s	128 MB	Judgeable
Managing AllowanceFind the smallest fixed withdrawal amount K so that the N daily costs can be covered using exactly M withdrawals, counting forced top-ups and optional extra ones.	Medium5	Binary searchGreedy+2	No attempts yet	1s	128 MB	Judgeable
ATM PIN TheftGiven a sequence of observed key presses (digits and at most one backspace), count the four-digit PINs that could produce exactly that sequence of pressed keys.	Medium5	Dynamic programmingCombinatorics+2	No attempts yet	1s	128 MB	Judgeable
Hopeless CoachGiven past win, draw, and loss counts, find the probability that the team earns at least P points over the next N matches.	Medium5	Dynamic programmingProbability+2	No attempts yet	1s	128 MB	Judgeable
Chessboard DanceSimulate a beetle on an 8x8 board following move and turn commands, pushing chains of pieces that may fall off the board.	Medium5	SimulationImplementation+2	No attempts yet	1s	128 MB	Judgeable
Crazy SearchCount how many distinct length-N substrings appear in a given text, where the text uses characters from an alphabet of size NC.	Medium5	StringHash map+2	No attempts yet	1s	128 MB	Judgeable
Erdös NumbersPapers list authors under titles, and each query asks the shortest co-authorship distance from Erdos; unreachable authors get infinity.	Medium5	GraphBFS+2	No attempts yet	1s	128 MB	Judgeable
Prime LandGiven an integer x in prime-base form (prime powers in decreasing order), print the same representation for x - 1.	Medium5	Number theoryMath+2	No attempts yet	1s	128 MB	Judgeable
FORCALRead text lines in blocks and scan each line into FORCAL tokens (identifiers, literals, symbols, keywords), printing TOKEN ERROR and skipping the block on an invalid string.	Medium5	StringImplementation+1	No attempts yet	1s	128 MB	Judgeable
PacketsGiven counts of 1x1 through 6x6 square tiles, find the minimum number of 6x6 parcels needed to pack them all.	Medium5	GreedyImplementation+2	No attempts yet	1s	128 MB	Judgeable
Extended Lights OutGiven a 5 by 6 Lights Out board, find the unique set of button presses that turns every light off, then print the press grid.	Medium5	Brute forceBit manipulation+2	No attempts yet	1s	128 MB	Judgeable
EntropyFor each line of text, print the fixed 8-bit ASCII bit length, the optimal prefix-free Huffman bit length, and the compression ratio rounded to one decimal.	Medium5	GreedyHeap+2	No attempts yet	1s	128 MB	Judgeable
AreaGiven the move vectors of a robot tracing a grid polygon, compute the number of interior grid points, boundary grid points, and the area using Pick's theorem.	Medium5	GeometryMath+2	No attempts yet	1s	128 MB	Judgeable
GridlandFor a rectangular grid of towns with eight-direction roads, compute the length of the shortest tour that visits every town once and returns to the start.	Medium5	MathGreedy+2	No attempts yet	1s	128 MB	Judgeable
Bit MapsConvert a rectangular bitmap between raw 0/1 array form and its recursive quadrant decomposition, honoring the split rules for odd dimensions.	Medium5	Divide and conquerRecursion+2	No attempts yet	1s	128 MB	Judgeable
String ComputerCompute the minimum number of single-character insert, delete, or change operations needed to turn one string into another.	Medium5	Dynamic programmingString+2	No attempts yet	1s	128 MB	Judgeable
Coconuts: The Second StoryFor each N, find the largest K such that K crew members can each remove one coconut, split the rest into K piles, and leave a final pile divisible by K.	Medium5	MathNumber theory+2	No attempts yet	1s	128 MB	Judgeable
Nonstop TravelGiven up to six traffic signals with green, yellow, and red timings starting at 2:00 AM, find all integer speeds from 30 to 60 mph that never hit a red light.	Medium5	SimulationMath+2	No attempts yet	1s	128 MB	Judgeable
Stockbroker GrapevineFor each directed weighted graph, find the vertex whose shortest paths reach every other vertex, minimizing the maximum distance; print it and that time, or disjoint.	Medium5	Shortest pathGraph+2	No attempts yet	1s	128 MB	Judgeable
FactFor each N up to 10000, find the last non-zero digit of N! and print it with N right-aligned in a field of width 5.	Medium5	MathNumber theory+2	No attempts yet	1s	128 MB	Judgeable
Horseshoe ScoringScore each four-toss turn by deciding ringer, toucher, swinger, or zero for each horseshoe and summing the points.	Medium5	GeometryImplementation+1	No attempts yet	1s	128 MB	Judgeable
Extrapolation Using a Difference TableExtend a sequence by k steps using a polynomial difference table, always assuming the highest-order differences stay constant, and print the (n+k)-th term.	Medium5	MathDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
Hi-QSimulate a peg solitaire game on a 33-hole plus board, always taking the move with the largest target then largest source, and report the sum of remaining peg holes.	Medium5	SimulationImplementation+1	No attempts yet	1s	128 MB	Judgeable
Call ForwardingGiven timestamped call forwarding rules, follow each call through the active chain, printing the final extension or 9999 if a loop is entered.	Medium5	SimulationHash map+2	No attempts yet	1s	128 MB	Judgeable
SlurpysGiven up to 10 short strings, decide whether each one is a Slurpy, meaning a Slimp followed by a Slump under the recursive grammar in the statement.	Medium5	RecursionString+2	No attempts yet	1s	128 MB	Judgeable
Power ShortageGiven a connected weighted undirected graph, keep a subset of roads so every pair of houses stays connected while maximizing the total length of removed roads.	Medium5	Minimum spanning treeGraph+2	No attempts yet	1s	256 MB	Judgeable
Broken KeyboardFor each test case, find the length of the longest substring of the sentence that contains at most m distinct characters.	Medium5	Sliding windowString+2	No attempts yet	1s	128 MB	Judgeable
El DoradoCount the increasing subsequences of length exactly k in a sequence of n distinct numbers, for several test cases.	Medium5	Dynamic programmingArray+1	No attempts yet	1s	128 MB	Judgeable
A Game with MarblesEach move takes one marble from a bowl and, if it is not bowl 1, adds one marble to every lower-numbered bowl; count the total moves until all bowls are empty.	Medium5	Dynamic programmingMath+1	No attempts yet	1s	128 MB	Judgeable
Grocery storeFind all quadruples of positive cent prices with equal sum and product totalling at most 20 euros, and print them in ascending lexicographic order.	Medium5	Brute forceMath+1	No attempts yet	1s	128 MB	Judgeable
Automatic Typo CorrectionGiven a dictionary, classify each queried word as correct, a misspelling of the first similar dictionary word, or unknown, using three specific edit types.	Medium5	StringHash map+2	No attempts yet	1s	128 MB	Judgeable
Basic Wall MazeGiven a 6 by 6 grid, three blocking walls, a start and an end square, print the lexicographically smallest shortest path using N, E, S, W moves.	Medium5	BFSGraph+2	No attempts yet	1s	128 MB	Judgeable
Wine Trading in GergoviaGiven net wine demands along a line summing to zero, find the minimum total transport cost (one unit per bottle per adjacent step).	Medium5	GreedyPrefix sum+2	No attempts yet	1s	128 MB	Judgeable
106 Miles to ChicagoGiven a graph where each edge has a percent probability of staying uncaught, find the path from node 1 to node n that maximizes the product of these probabilities.	Medium5	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
In DangerGiven n people in a circle where every second person is eliminated starting from person 1, report the final surviving position; n arrives encoded as xyez.	Medium5	MathRecursion+2	No attempts yet	1s	128 MB	Judgeable
Assistance RequiredGenerate lucky numbers by repeatedly removing every k-th remaining element, and report the n-th lucky number for each query.	Medium5	SimulationImplementation+2	No attempts yet	1s	128 MB	Judgeable
The Sierpinski FractalDraw the outline of a depth-n Sierpinski triangle in ASCII, 2^n rows tall, with no trailing spaces and blank lines between the test cases.	Medium5	Divide and conquerRecursion+2	No attempts yet	1s	128 MB	Judgeable
Code the TreeParse a parenthesized tree description, then repeatedly remove the smallest-numbered leaf and print its neighbor to build the Prufer code.	Medium5	TreeImplementation+2	No attempts yet	1s	128 MB	Judgeable
Decode the TreeGiven a Prüfer code, rebuild the labeled tree on n vertices and print it as a canonical rooted word with children sorted by number.	Medium5	TreeHeap+2	No attempts yet	1s	128 MB	Judgeable
Anagram GroupsGroup distinct words that are anagrams of each other, then print the five largest groups sorted by size and smallest word.	Medium5	Hash mapSorting+2	No attempts yet	1s	128 MB	Judgeable
EquidistanceGiven coordinates of locations on a sphere, for each query find the surface distance from a third point to the great circle equidistant from two given points.	Medium5	GeometryMath+2	No attempts yet	1s	128 MB	Judgeable
Counting Fibonacci NumbersFor each query pair a and b up to 10^100, count how many Fibonacci numbers fall in the closed interval [a, b].	Medium5	MathBinary search+2	No attempts yet	1s	256 MB	Judgeable
Bee MajaConvert a spiral hex-grid cell number into hexagonal axial coordinates using the orientation shown in the sample.	Medium5	MathImplementation+2	No attempts yet	1s	128 MB	Judgeable
Quad TreeDecode a quad tree string into an n by n black and white image, then print each row as XBM hexadecimal bytes.	Medium5	RecursionDivide and conquer+2	No attempts yet	1s	128 MB	Judgeable
FriendsEvaluate set expressions over uppercase letters using union, intersection, and difference, where * binds tighter than + and - and equal operators left-associate.	Medium5	StringStack+2	No attempts yet	1s	128 MB	Judgeable
Team QueueSimulate a team queue where each new element cuts in behind its own teammates, if any, and otherwise joins the tail; print every dequeued element.	Medium5	QueueHash map+2	No attempts yet	1s	128 MB	Judgeable
France '98Given win probabilities for every pair of 16 teams and a fixed bracket, compute each team's probability of winning the single-elimination tournament.	Medium5	Dynamic programmingProbability+2	No attempts yet	1s	128 MB	Judgeable
Solving Linear EquationsParse each linear equation written in a recursive grammar with parentheses and multiplication, then report no, infinite, or the unique solution rounded to six decimals.	Medium5	MathRecursion+2	No attempts yet	1s	128 MB	Judgeable
Eeny Meeny MooFor each n, find the smallest step size m so that in the elimination order starting at city 1, city 2 is eliminated last.	Medium5	SimulationBrute force+2	No attempts yet	1s	128 MB	Judgeable
Humble NumbersFor each n up to 5842, print the nth number whose only prime factors are 2, 3, 5, or 7, formatted with the correct English ordinal suffix.	Medium5	Dynamic programmingMath+2	No attempts yet	1s	128 MB	Judgeable
Rhinoceros BeetleGiven shared community cards and each player's two hole cards, evaluate every player's best five-card poker hand and print the indices of all winners.	Medium5	ImplementationSorting+2	No attempts yet	2s	128 MB	Judgeable
Collatz ConjectureFor each pair A and B, generate both Collatz sequences up to 1 and find the first value they share, reporting its index in each sequence.	Medium5	SimulationHash map+2	No attempts yet	1s	128 MB	Judgeable
String EncryptionClean the plaintext (drop spaces, uppercase), then invert the given transposition decryption rule to produce the matching ciphertext.	Medium5	StringImplementation+2	No attempts yet	1s	128 MB	Judgeable
God Save the i-th QueenGiven a board and placed queens, count empty squares not sharing a row, column, or diagonal with any queen.	Medium5	ArrayHash map+2	No attempts yet	1s	128 MB	Judgeable
Clock CaptchaDecode a 7-line seven-segment clock image with dots as wildcards and print the unique valid time or ambiguous.	Medium5	ImplementationSimulation+1	No attempts yet	1s	128 MB	Judgeable
Peculiar PrimesList every integer in [X, Y] whose prime factors all belong to a given set of at most 10 primes, or print none.	Medium5	BacktrackingMath+2	No attempts yet	1s	128 MB	Judgeable
Railway TransportationSplit the arrival sequence into the fewest contiguous-order groups, each nondescending in arrival order, and report the count or failure if it exceeds M.	Medium5	GreedyBinary search+1	No attempts yet	1s	128 MB	Judgeable
C-Style LoopsCount the iterations of a C for loop whose counter wraps modulo 2^k, or report FOREVER if it never reaches the stopping value.	Medium5	MathNumber theory+2	No attempts yet	1s	128 MB	Judgeable
Building a New DepotGiven the corner posts of an axis-aligned rectilinear polygon (listed in no particular order), reconstruct the polygon and compute its total perimeter.	Medium5	GeometrySorting+2	No attempts yet	1s	128 MB	Judgeable
StorehouseGiven a sequence of truck cargo requests and B bays, decide which bay holds which cargo type to minimize the number of loads, assuming optimal offline knowledge.	Medium5	GreedyHash map+1	No attempts yet	1s	128 MB	Judgeable
Sea BattleCount rectangular ships of '#' cells on a grid, verify no two touch even diagonally, and report bad placement if the ships are not valid rectangles.	Medium5	ImplementationArray+2	No attempts yet	1s	128 MB	Judgeable
The Die Is CastRead a pixel image, split non-background pixels into dice connected by shared edges, count the dot regions inside each die, and print the counts sorted.	Medium5	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
The Perfect SymmetryGiven a set of distinct integer points, decide whether it has a center of symmetry and, if so, print that center to one decimal place.	Medium5	Hash mapGeometry+2	No attempts yet	1s	128 MB	Judgeable
Spiderman's WorkoutAssign plus or minus signs to the distances so the partial sums stay at or above 0 and return to 0 at the end, minimizing the peak height.	Medium5	Dynamic programmingGreedy+2	No attempts yet	1s	128 MB	Judgeable
Tournament RankingGiven game results between teams, produce the lexicographically smallest topological order, or report that no valid ranking exists due to a cycle.	Medium5	GraphTopological sort+2	No attempts yet	1s	128 MB	Judgeable
Traffic PlanningGiven a directed graph and a start node, list the nodes not reachable from the start by a path of one or more edges; print OK if none.	Medium5	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
Median Weight BeadGiven weighted comparisons between beads, count how many beads cannot be the median because at least (N+1)/2 beads are known heavier or lighter.	Medium5	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
Choose Your Own ArithmeticGiven working digits and exactly W add-or-multiply steps applied left to right from a single digit, decide whether each target value is reachable.	Medium5	Brute forceDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Alice Through the Looking GlassGiven a magnification level and a cell coordinate, decide whether that cell of the 5^m by 5^m self-similar grid is filled or empty.	Medium5	RecursionDivide and conquer+1	No attempts yet	2s	512 MB	Judgeable
Putnam Rank RangeGiven the average rank for each distinct score, find the rank range occupied by the block of contestants holding your score.	Medium5	MathImplementation	No attempts yet	2s	512 MB	Judgeable
Spies Like UsGiven a bipartite graph, decide whether any two vertices on the same side share at most one common neighbor on the other side.	Medium5	GraphHash map+2	No attempts yet	2s	512 MB	Judgeable
Barking Dogs!Given dogs with wake-up delays and a directed hearing graph, simulate who barks each second from 0 to T and count each dog's barks.	Medium5	SimulationGraph+2	No attempts yet	2s	512 MB	Judgeable
ShuffleGiven a permutation of 27 characters, apply it N times to a short string and print the result.	Medium5	ImplementationMath+2	No attempts yet	2s	512 MB	Judgeable
Degrees of SeparationMaintain a friendship graph under edge insertions and deletions, and answer queries about friend counts, friends-of-friends counts, and shortest-path distance between two people.	Medium5	GraphBFS+2	No attempts yet	1s	128 MB	Judgeable
NukitGiven counts of particles A, B, C, D, two players alternately remove one of five fixed multisets; find who wins under optimal play.	Medium5	Game theoryDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
Twenty-fourFor each hand of four cards, find the largest integer value at most 24 reachable by an expression that uses all four values with +, -, *, / and only exact division.	Medium5	Brute forceRecursion+2	No attempts yet	1s	128 MB	Judgeable
Moving DayGiven n people each moving from one address to another on a single street, find the lexicographically smallest order of moves so every destination is vacant in time.	Medium5	GraphTopological sort+1	No attempts yet	1s	128 MB	Judgeable
SnowflakesGiven up to 100,000 snowflakes of six arm lengths each, find whether two are identical under cyclic rotation or reversal.	Medium5	Hash mapString+2	No attempts yet	1s	128 MB	Judgeable
CN TowerGiven angles of landmarks around a rotating restaurant that turns 360 degrees every 72 minutes, find the shortest time window covering all distinct angles.	Medium5	SortingTwo pointers+2	No attempts yet	1s	128 MB	Judgeable
BananasDecide for each word whether it fits the recursive grammar of a monkey language, where words wrap other words in N and in B...S.	Medium5	StringRecursion+2	No attempts yet	1s	128 MB	Judgeable
Quantum OperationsCompute the tensor product of several integer matrices and report its element extremes plus maximum and minimum row and column sums.	Medium5	ImplementationMatrix+2	No attempts yet	1s	128 MB	Judgeable
Pinball RankingGiven scores in play order, compute each game's rank as one plus the number of earlier-or-later scores strictly above it, then output the average rank as a reduced fraction.	Medium5	Binary searchSorting+2	No attempts yet	1s	128 MB	Judgeable
SpreadsheetEvaluate each spreadsheet cell, treating formula cells as sums of other cells, and mark any cell involved in a dependency cycle as undefined.	Medium5	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
Super PlumberFind the maximum total coin value on a path from the bottom-left to the bottom-right of a grid where SP moves right, up, or down without revisiting cells.	Medium5	Dynamic programmingImplementation	No attempts yet	1s	128 MB	Judgeable
ScribbleGiven seven tiles with letter values and a dictionary of up to 100000 words, find the highest-scoring dictionary word formable from the tiles, or 0 if none is.	Medium5	StringHash map+2	No attempts yet	1s	128 MB	Judgeable
SpamCount trigram frequencies in sample spam and non-spam messages, then classify each test message by which sample it matches more closely under the cosine similarity measure.	Medium5	StringHash map+2	No attempts yet	1s	128 MB	Judgeable
CookiesGiven up to 10 points, find the diameter of the smallest enclosing circle.	Medium5	GeometryBrute force+2	No attempts yet	1s	128 MB	Judgeable