Problems

Pick a problem, code in the editor, and watch the judge run real test cases. The archive is open to browse

Under construction

Still being built. Things may change

Total results29,450 problems

Cheating a Boolean Tree (Small)
Medium5
Tree, Dynamic programming
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Cheating a Boolean Tree (Large)
Medium5
Dynamic programming, Tree+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Milkshakes (Small)
Medium5
Greedy, Implementation+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Saving the Universe
Medium5
Greedy, Implementation
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Saving the Universe (Large)
Medium5
Greedy, Implementation+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Longest Increasing Subsequence 3
Medium5
Dynamic programming, Binary search
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Color Wheel (Small)
Medium5
Simulation, String+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Traffic (Small)
Medium5
Tree, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Legendary JBNU
Medium5
Array, Sorting+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Roller Coaster
Medium5
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Branch Assignment
Medium5
Graph, Shortest path+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
String Theory
Medium5
Dynamic programming, String+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Inha Suit
Medium5
Dynamic programming, Graph+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Doki Doki Snack Handout
Medium5
Stack, Simulation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Name Generator
Medium5
String, Greedy+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Bus Routes
Medium5
Tree, Math+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Seat Assignment
Medium5
Greedy, Sorting+1
No attempts yet
Time limit
0.8s
Memory limit
32 MB
Judgeable
A Walk Around the Main Campus
Medium5
Dynamic programming, Graph+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Make It One 2
Medium5
Dynamic programming, BFS+1
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Junseo the Librarian King
Medium5
Dynamic programming, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
N-dimensional travel
Medium5
Hash map, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Souvenir
Medium5
Simulation, Queue+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Birthday Presents
Medium5
Sorting, Sliding window+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cheating a Boolean Tree
Medium5
Tree, Dynamic programming
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Handing out candies
Medium5
Dynamic programming, Combinatorics
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Magic Potion
Medium5
Shortest path, Graph+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hosting Contests
Medium5
Greedy, Binary search
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
A and B 2
Medium5
String, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Nice Pairs
Medium5
String, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Multiple Switches
Medium5
Greedy, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Double and Add
Medium5
Greedy, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Ducks
Medium5
Greedy, Simulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Trees and Path Lengths 2
Medium5
Math, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tree with the longest diameter
Medium5
Tree, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Palindromic substrings
Medium5
Brute force, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Turn Game 2
Medium5
Math, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
pqr
Medium5
Combinatorics, Number theory+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Movement 3
Medium5
Math, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Powers of Three Walk
Medium5
Math, Number theory+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Turning A into B
Medium5
String, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
ABCDE
Medium5
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Centipede legs
Medium5
Math, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Beehive
Medium5
Math, Geometry+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
DNA Sequencing
Medium5
Trie, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Counting Music Scores
Medium5
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Distinct rational numbers
Medium5
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Change a Password
Medium5
Brute force, Sorting+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Aurora Princess
Medium5
Graph, DFS+1
No attempts yet
Time limit
1s
Memory limit
32 MB
Judgeable
Grid Forest
Medium5
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
32 MB
Judgeable
Intervals of Unique Numbers
Medium5
Two pointers, Sliding window+2
No attempts yet
Time limit
1s
Memory limit
32 MB
Judgeable
Make all numbers equal 2
Medium5
Greedy, Implementation
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Dwarves
Medium5
Graph, Topological sort+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Selling CPUs
Medium5
Dynamic programming, Greedy
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Maze
Medium5
Probability, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Window
Medium5
Math, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Two Stage Router
Medium5
Graph, Implementation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Spontaneous Trip
Medium5
Probability, Dynamic programming+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Smallest possible poll sample
Medium5
Math, Brute force
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Torres del Paine
Medium5
Geometry, Math
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Minimum Swaps
Medium5
Array, Hash map+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Train Line Construction
Medium5
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Secret Password
Medium5
String matching, Array+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Bits Equalizer
Medium5
Greedy, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Lucky Tickets
Medium5
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Ecology
Medium5
Dynamic programming, Probability+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Fibonacci Chicken
Medium5
Dynamic programming, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Resort
Medium5
Dynamic programming, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Gas Stations
Medium5
Greedy, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Equal leaf distances
Medium5
Tree, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Hamming Ellipses
Medium5
Combinatorics, Math+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Memory Match
Medium5
Simulation, Hash map+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Presidential Elections
Medium5
Greedy, Sorting
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Fleecing the Raffle
Medium5
Math, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cyclic Triangle
Medium5
Math, Implementation+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Water Pump
Medium5
Array, Prefix sum
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Contiguous Sum 2
Medium5
Dynamic programming, Array
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hidden Anagrams
Medium5
Hash map, String+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Coprime Pairs
Medium5
Number theory, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Othello Rearrangement
Medium5
Greedy, Math+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Tangsuyuk Game
Medium5
String, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Trading Union Departures
Medium5
Graph, Simulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hard Cuts
Medium5
Dynamic programming, Implementation
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Manta Ray
Medium5
Geometry, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hide and Seek 3
Medium5
BFS, Graph+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Number of arithmetic triples
Medium5
Hash map, Math
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Soccer Game
Medium5
Greedy, Sorting
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Percolation
Medium5
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Jewelry Store
Medium5
Dynamic programming, Combinatorics
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Rouba-Monte
Medium5
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Guess the Number from Divisors and Multiples
Medium5
Number theory, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Isosceles Cube Triangle
Medium5
Array, Brute force+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Mário's Lockers
Medium5
Sliding window, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Command History
Medium5
Array, Hash map+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Stock exchange
Medium5
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Tri-du
Medium5
Math, Probability+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Sum of Factorials
Medium5
Dynamic programming, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Loteria
Medium5
Math, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Shuffled Deck
Medium5
Math, Sorting+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
RSA
Medium5
Number theory, Math
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Grandpa Pepe's Pizza
Medium5
Math, Implementation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Cheating a Boolean Tree (Small)Given a complete boolean tree with switchable gates, find the minimum number of gate flips so the root evaluates to V.	Medium5	TreeDynamic programming	No attempts yet	5s	512 MB	Judgeable
Cheating a Boolean Tree (Large)Given a complete binary tree of AND/OR gates with fixed leaf values, find the fewest changeable gates to flip so the root equals V, or report IMPOSSIBLE.	Medium5	Dynamic programmingTree+2	No attempts yet	5s	512 MB	Judgeable
Milkshakes (Small)Assign each flavor malted or unmalted so every customer gets a liked type, minimizing malted batches, with at most one malted liked type per customer.	Medium5	GreedyImplementation+2	No attempts yet	5s	512 MB	Judgeable
Saving the UniverseGiven a stream of queries, each matching one engine's name, find the fewest engine switches needed to serve all queries without matching a query's name.	Medium5	GreedyImplementation	No attempts yet	5s	512 MB	Judgeable
Saving the Universe (Large)Given a query stream and a set of engines, choose which engine handles each query, never an engine matching the query, to minimize the number of switches.	Medium5	GreedyImplementation+2	No attempts yet	5s	512 MB	Judgeable
Longest Increasing Subsequence 3Given a sequence of up to 10^6 integers, find the length of the longest strictly increasing subsequence.	Medium5	Dynamic programmingBinary search	No attempts yet	3s	512 MB	Judgeable
Color Wheel (Small)Repaint a circular string of R, G, B cells K times by a local rule, then report the final count of each color.	Medium5	SimulationString+1	No attempts yet	1s	256 MB	Judgeable
Traffic (Small)Given a tree and Q tickets, count how many tickets use each edge along the unique path, then report the edge with the largest count (smallest station pair on ties).	Medium5	TreePrefix sum+2	No attempts yet	2s	512 MB	Judgeable
Legendary JBNUMaintain a set of integer keys with values, supporting insert, update-by-nearest-key, and query that prints the nearest key's value, -1, or ?.	Medium5	ArraySorting+2	No attempts yet	2s	128 MB	Judgeable
Roller CoasterFrom a sequence of column heights, delete columns so the survivors strictly decrease then strictly increase (either part may be empty); output the maximum number of survivors.	Medium5	Dynamic programmingArray+2	No attempts yet	1s	128 MB	Judgeable
Branch AssignmentPartition b branches into s nonempty groups to minimize total round-trip courier distance, where a message from branch i to j costs dist(i,hq)+dist(hq,j).	Medium5	GraphShortest path+1	No attempts yet	5s	512 MB	Judgeable
String TheoryGiven alternating runs of quote characters, find the largest k for which the whole string is a k-quotation.	Medium5	Dynamic programmingString+1	No attempts yet	2s	512 MB	Judgeable
Inha SuitStarting at height 1, choose one of five moves before each tree so the height lands on a hole, minimizing teleport (T) uses within limit K.	Medium5	Dynamic programmingGraph+1	No attempts yet	1s	128 MB	Judgeable
Doki Doki Snack HandoutGiven a queue of numbered students, check whether they can be passed out in order 1 to N using one last-in-first-out holding spot.	Medium5	StackSimulation	No attempts yet	1s	128 MB	Judgeable
Name GeneratorSplit a string into k different non-empty consecutive parts, or report that no such split exists, choosing the lexicographically smallest sequence.	Medium5	StringGreedy+1	No attempts yet	2s	256 MB	Judgeable
Bus RoutesOn a tree with N stops, every ordered pair sends a bus along the unique path; for each stop count how many of the N(N-1) buses halt there, including endpoints.	Medium5	TreeMath+1	No attempts yet	3s	1024 MB	Judgeable
Seat AssignmentAssign seats left to right, each time giving the seat to the still-unseated request with the smallest right endpoint that covers it.	Medium5	GreedySorting+1	No attempts yet	0.8s	32 MB	Judgeable
A Walk Around the Main CampusCount closed walks of exactly D minutes from the Information Science Building in a fixed eight-building graph, modulo 1e9+7.	Medium5	Dynamic programmingGraph+1	No attempts yet	1s	512 MB	Judgeable
Make It One 2Find the fewest operations (divide by 3, divide by 2, or subtract 1) turning N into 1, and print the lexicographically smallest shortest path.	Medium5	Dynamic programmingBFS+1	No attempts yet	0.5s	512 MB	Judgeable
Junseo the Librarian KingGiven book numbers and weights, move the lightest total weight of books so the numbers end up in non-decreasing order.	Medium5	Dynamic programmingSorting+2	No attempts yet	2s	512 MB	Judgeable
N-dimensional travelGiven a walk on an N-dimensional integer grid as a list of coordinate indices and signs, decide whether all visited points, including start and end, are distinct.	Medium5	Hash mapImplementation+2	No attempts yet	2s	512 MB	Judgeable
SouvenirParticipants sit in a circle; stage t removes the t^3-th person counting clockwise from the current host, and you find the last survivor.	Medium5	SimulationQueue+2	No attempts yet	2s	512 MB	Judgeable
Birthday PresentsPick a subset of presents whose price range is below D, maximizing total satisfaction.	Medium5	SortingSliding window+2	No attempts yet	2s	512 MB	Judgeable
Cheating a Boolean TreeIn a tournament-style Boolean tree, flip the fewest changeable AND/OR gates so the root evaluates to V, or report it impossible.	Medium5	TreeDynamic programming	No attempts yet	2s	512 MB	Judgeable
Handing out candiesFor every K, count the ways to choose one candy of each brand 1 through K, and print the total over all K.	Medium5	Dynamic programmingCombinatorics	No attempts yet	2s	512 MB	Judgeable
Magic PotionGiven a complete graph with edge weights and K potions that halve one trip's time, find the shortest time from city 0 to city 1.	Medium5	Shortest pathGraph+1	No attempts yet	2s	512 MB	Judgeable
Hosting ContestsGiven counts of five problem groups, each usable at one of its allowed difficulty slots, find the maximum number of easy-medium-hard contests.	Medium5	GreedyBinary search	No attempts yet	2s	512 MB	Judgeable
A and B 2Given two strings of A and B, decide whether repeatedly appending A or appending B then reversing can turn S into T.	Medium5	StringGreedy+2	No attempts yet	2s	512 MB	Judgeable
Nice PairsCount pairs (x, y) with A <= x < y <= B where y is a rotation of x's digits (a suffix moved to the front), counting duplicates only once.	Medium5	StringMath+2	No attempts yet	2s	512 MB	Judgeable
Multiple SwitchesGiven N bulbs as Y/N, find the fewest presses of switches that flip multiples to turn all bulbs off, or -1 if impossible.	Medium5	GreedyMath+2	No attempts yet	2s	512 MB	Judgeable
Double and AddStarting from an all-zero array, find the minimum number of single-element increments and whole-array doublings that produce the target array B.	Medium5	GreedyBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
DucksSplit a string of q,u,a,c,k into the fewest interleaved subsequences, each reading as 'quack' repeated.	Medium5	GreedySimulation+1	No attempts yet	2s	512 MB	Judgeable
Trees and Path Lengths 2Find leaf counts p, q, r on a fixed 4-vertex path so the tree has exactly S length-3 paths, minimizing N then (p,q,r).	Medium5	MathImplementation+2	No attempts yet	2s	512 MB	Judgeable
Tree with the longest diameterGiven the number of vertices at each level from the root, build a tree realizing those level counts with the maximum possible diameter.	Medium5	TreeGreedy+2	No attempts yet	2s	512 MB	Judgeable
Palindromic substringsCount length-N uppercase strings whose length-M substrings include at least K palindromes.	Medium5	Brute forceString+2	No attempts yet	2s	512 MB	Judgeable
Turn Game 2Decide whether turn wins of weights 1, 3, 5, ... can give Yunho x and Donghyeok y points, minimizing Yunho's wins.	Medium5	MathGreedy+1	No attempts yet	2s	512 MB	Judgeable
pqrCount index triples p<q<r whose product A[p]A[q]A[r] is divisible by K, for N up to 2000.	Medium5	CombinatoricsNumber theory+1	No attempts yet	2s	512 MB	Judgeable
Movement 3Decide whether (x, y) is reachable by moving 3^k right or up on each step k, starting at the origin.	Medium5	MathBit manipulation+1	No attempts yet	2s	512 MB	Judgeable
Powers of Three WalkGiven a target point, decide whether it is reachable if stage k moves exactly 3^k in one of the four axis directions.	Medium5	MathNumber theory+1	No attempts yet	2s	512 MB	Judgeable
Turning A into BGiven two equal-length uppercase strings A and B, find the minimum number of moves that bring a chosen character to the front of A so that A becomes B, or -1 if impossible.	Medium5	StringGreedy+2	No attempts yet	2s	512 MB	Judgeable
ABCDEGiven an undirected friendship graph, decide whether it contains a simple path of five distinct vertices, that is, a path with four edges.	Medium5	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
Centipede legsGiven n and m notes, choose left and right leg counts summing to n, both at least 1, maximizing how many notes have l_i <= left and r_i <= right, breaking ties by smallest left count.	Medium5	MathPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
BeehiveGiven two cell indices in an infinite hexagonal beehive numbered by distance from cell 1, find the grid distance between those cells.	Medium5	MathGeometry+1	No attempts yet	2s	512 MB	Judgeable
DNA SequencingEach printed line can be trimmed to any prefix; pick prefixes of length at least M so the number of distinct resulting strings is maximized.	Medium5	TrieString+2	No attempts yet	2s	512 MB	Judgeable
Counting Music ScoresCount scores over two pitches and two durations with n seconds total, balanced pitch counts, at least as many long notes as short, and alternating pitches starting low.	Medium5	CombinatoricsDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Distinct rational numbersCount distinct values of a/b with 0 <= a <= b <= N, i.e. fractions in [0,1] with reduced denominator at most N.	Medium5	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Change a PasswordGiven an old N-digit password, find the length-N permutation of distinct digits that maximizes the cyclic distance from the old value, breaking ties by smallest number.	Medium5	Brute forceSorting+2	No attempts yet	5s	512 MB	Judgeable
Aurora PrincessGiven each person's parents and a list of people who die or leave the country, count how many remain alive with both parents alive in Korea.	Medium5	GraphDFS+1	No attempts yet	1s	32 MB	Judgeable
Grid ForestOn the integer lattice, one unit step moves between adjacent trees; find the shortest walk from (x, y) to the origin that keeps the origin visible at every stop.	Medium5	MathNumber theory+2	No attempts yet	1s	32 MB	Judgeable
Intervals of Unique NumbersCount pairs (i, j) where the subarray from i to j has all distinct values, with N up to 100000.	Medium5	Two pointersSliding window+2	No attempts yet	1s	32 MB	Judgeable
Make all numbers equal 2Given a sequence where one Add raises a whole run of equal neighboring values by 1, find the minimum number of Adds to make all values equal.	Medium5	GreedyImplementation	No attempts yet	2s	512 MB	Judgeable
DwarvesGiven strict size comparisons between named dwarves, decide whether the statements are mutually consistent.	Medium5	GraphTopological sort+2	No attempts yet	2s	512 MB	Judgeable
Selling CPUsSell up to c CPUs across m ordered merchants, each paying p_i for exactly i CPUs in one deal, to maximize total money.	Medium5	Dynamic programmingGreedy	No attempts yet	2s	512 MB	Judgeable
MazeBob moves through a multi-graph where each letter opens doors with that label; given the letter sequence, compute the probability he reaches room n, choosing uniformly among available matching doors.	Medium5	ProbabilityDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
WindowPick a uniformly random axis-aligned subrectangle of an H by W grid; find the expected number of cells times 9, modulo 1e9+7.	Medium5	MathCombinatorics+2	No attempts yet	1s	512 MB	Judgeable
Two Stage RouterGiven N, a connection cap, and a power cap, construct a two-stage router graph with collectors and distributors that satisfies all correctness conditions.	Medium5	GraphImplementation+1	No attempts yet	2s	512 MB	Judgeable
Spontaneous TripGiven flight counts between airports, find the most likely airport reached after exactly K random flights starting from ICN.	Medium5	ProbabilityDynamic programming+1	No attempts yet	3s	256 MB	Judgeable
Smallest possible poll sampleGiven a percentage printed to three decimals, find the smallest sample size n for which some count k rounds to that percentage.	Medium5	MathBrute force	No attempts yet	1s	256 MB	Judgeable
Torres del PaineFor each test case, compute the area inside a rectangle from which three given points are seen in a fixed clockwise order.	Medium5	GeometryMath	No attempts yet	1s	256 MB	Judgeable
Minimum SwapsGiven permutations A and B, find the minimum number of swaps within A that turn it into B.	Medium5	ArrayHash map+2	No attempts yet	1s	64 MB	Judgeable
Train Line ConstructionOn an N by N grid with resident counts and blocked cells, find a 4-direction path between two stations minimizing the sum of cell weights along it.	Medium5	GraphShortest path+2	No attempts yet	1s	64 MB	Judgeable
Secret PasswordGiven two length-N sequences, decide whether one is a cyclic rotation of the other.	Medium5	String matchingArray+2	No attempts yet	1s	64 MB	Judgeable
Bits EqualizerGiven S with 0, 1, ? and T with 0 and 1, find the fewest moves (0 to 1, ? to 0 or 1, swap two positions) to turn S into T, or -1.	Medium5	GreedyString+2	No attempts yet	2s	512 MB	Judgeable
Lucky TicketsCount digit strings of length 2N whose first N digits sum to the same value as the last N digits, modulo 1e9+7.	Medium5	Dynamic programmingCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
EcologyCompute the probability that exactly M of N birds wear a tracker after D days of catching C random birds each day.	Medium5	Dynamic programmingProbability+1	No attempts yet	2s	512 MB	Judgeable
Fibonacci ChickenGiven N, split it into Fibonacci-derived (people, chicken) pairs whose people counts sum to N, and report the minimum and maximum total chickens.	Medium5	Dynamic programmingMath+2	No attempts yet	1s	128 MB	Judgeable
ResortChoose one-day, 3-day, and 5-day passes over a vacation with blocked days so every open day is covered at minimum cost, where 3 coupons buy a free one-day pass.	Medium5	Dynamic programmingGreedy+1	No attempts yet	2s	512 MB	Judgeable
Gas StationsGiven road lengths and per-city fuel prices on a line, buy fuel along the way to minimize the total cost of driving from the first city to the last.	Medium5	GreedyArray+2	No attempts yet	2s	512 MB	Judgeable
Equal leaf distancesRaise edge weights in a weighted perfect binary tree so every root-to-leaf path has equal length, minimizing the total weight.	Medium5	TreeGreedy+2	No attempts yet	1s	512 MB	Judgeable
Hamming EllipsesCount words of length n over a q-symbol alphabet whose Hamming distances to two given words sum to exactly D.	Medium5	CombinatoricsMath+2	No attempts yet	5s	512 MB	Judgeable
Memory MatchGiven the history of a Memory match game, find how many pairs you can guarantee scoring on the current turn.	Medium5	SimulationHash map+1	No attempts yet	5s	512 MB	Judgeable
Presidential ElectionsGiven per-state delegates, fixed votes, and undecided voters, find the minimum number of undecided voters to convince so the Constituents win a delegate majority, with ties going to the Federals.	Medium5	GreedySorting	No attempts yet	5s	512 MB	Judgeable
Fleecing the RaffleAdd k slips with your name to a box of n slips so the chance your name is drawn exactly once among p draws is maximized.	Medium5	MathCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Cyclic TriangleGiven a triangle size and cell coordinates, report the digit placed at that cell by the spiral border-filling order.	Medium5	MathImplementation+1	No attempts yet	5s	512 MB	Judgeable
Water PumpPlace one pump in a cell, let water drain toward it from both sides, and find the cell that removes the most water.	Medium5	ArrayPrefix sum	No attempts yet	2s	512 MB	Judgeable
Contiguous Sum 2Find the maximum contiguous subarray sum after optionally deleting at most one element from the sequence.	Medium5	Dynamic programmingArray	No attempts yet	2s	512 MB	Judgeable
Hidden AnagramsGiven two lowercase strings s1 and s2, find the maximum length of a substring of s1 that is an anagram of some substring of s2.	Medium5	Hash mapString+2	No attempts yet	10s	512 MB	Judgeable
Coprime PairsGiven N, count the unordered pairs of coprime natural numbers whose least common multiple equals N.	Medium5	Number theoryMath	No attempts yet	1s	128 MB	Judgeable
Othello RearrangementGiven two length-N strings of W and B, find the minimum number of swap-two-positions and flip-one-piece operations to turn the start into the target.	Medium5	GreedyMath+1	No attempts yet	2s	256 MB	Judgeable
Tangsuyuk GameGiven a word of distinct letters, find the shortest memorized cyclic string each player repeats to always say the correct next letter.	Medium5	StringMath+1	No attempts yet	1s	128 MB	Judgeable
Trading Union DeparturesStarting from country L leaving, each country exits once at least half its original partners have left; decide whether X exits too.	Medium5	GraphSimulation+1	No attempts yet	2s	512 MB	Judgeable
Hard CutsFor each w by h rectangle, find the minimum number of integer-sided squares that tile it exactly.	Medium5	Dynamic programmingImplementation	No attempts yet	2s	256 MB	Judgeable
Manta RayFor each data set, count the plankton points that fall inside the rectangle swept by a mouth of width w moving distance t in direction alpha.	Medium5	GeometryMath+2	No attempts yet	2s	512 MB	Judgeable
Hide and Seek 3Given start N and target K, find the minimum number of one-step moves when moving X to X-1 or X+1 costs one second and moving X to 2X costs nothing.	Medium5	BFSGraph+1	No attempts yet	2s	512 MB	Judgeable
Number of arithmetic triplesCount index triples i < j < k where the three values A_i, A_j, A_k form an arithmetic progression.	Medium5	Hash mapMath	No attempts yet	3s	512 MB	Judgeable
Soccer GameGiven n teams and their reported win counts in a round-robin with no ties, decide if some set of match results produces exactly those scores.	Medium5	GreedySorting	No attempts yet	2s	512 MB	Judgeable
PercolationGiven an M by N grid of conducting (0) and blocking (1) cells, decide whether any conducting cell in the top row connects to a conducting cell in the bottom row through edge-adjacent conducting cells.	Medium5	GraphDFS+2	No attempts yet	1s	512 MB	Judgeable
Jewelry StoreWith unlimited gems of each of N kinds, list all total values obtainable by choosing exactly K gems.	Medium5	Dynamic programmingCombinatorics	No attempts yet	5s	512 MB	Judgeable
Rouba-MonteSimulate a card game where players draw, steal montes, and discard mismatches; report the winners by monte size.	Medium5	SimulationImplementation+2	No attempts yet	1s	512 MB	Judgeable
Guess the Number from Divisors and MultiplesGiven A, B, C, D, find the smallest N where A divides N, B does not, N divides C, and N does not divide D, or print -1.	Medium5	Number theoryMath+1	No attempts yet	1s	512 MB	Judgeable
Isosceles Cube TriangleGiven column heights, find the largest h such that some 2h-1 consecutive columns can all be reduced to the shape 1,2,...,h,...,2,1.	Medium5	ArrayBrute force+1	No attempts yet	1s	512 MB	Judgeable
Mário's LockersGiven the positions of L free lockers, find the minimum number of swaps to gather N of them into consecutive positions.	Medium5	Sliding windowPrefix sum+2	No attempts yet	1s	512 MB	Judgeable
Command HistoryGiven a sequence of positions in a command history, simulate running each command by the nearest occurrence and total the up-arrow presses needed.	Medium5	ArrayHash map+2	No attempts yet	1s	512 MB	Judgeable
Stock exchangeGiven daily prices and a fixed fee per buy, find the maximum total profit when holding at most one share at a time and each share must be sold later.	Medium5	Dynamic programmingGreedy+2	No attempts yet	1s	512 MB	Judgeable
Tri-duGiven two known card values, pick a third value from 1 to 13 that maximizes the chance of holding a winning triple or pair against one opponent.	Medium5	MathProbability+1	No attempts yet	1s	512 MB	Judgeable
Sum of FactorialsGiven N up to 100000, find the fewest factorials (repeats allowed) whose sum equals N.	Medium5	Dynamic programmingMath+1	No attempts yet	1s	512 MB	Judgeable
LoteriaDecide whether K target parities can be chosen so that no non-empty subset of the given rows has column sums matching all of them.	Medium5	MathBit manipulation+2	No attempts yet	1s	512 MB	Judgeable
Shuffled DeckFor a deck of P distinct cards, find how many times the given interleaving shuffle must be repeated until the deck returns to its sorted order.	Medium5	MathSorting+1	No attempts yet	2s	512 MB	Judgeable
RSAFactor N into its two primes to recover phi(N), then use modular inverse and fast exponentiation to decrypt C and print M.	Medium5	Number theoryMath	No attempts yet	2s	512 MB	Judgeable
Grandpa Pepe's PizzaGiven N olive positions on a circle of circumference C, decide whether equal sectors of length C/N can each contain exactly one olive.	Medium5	MathImplementation+1	No attempts yet	2s	512 MB	Judgeable