Problems

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Total results29,068 problems

Aurora Borealis
Medium7
Geometry, Binary search+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Bribing the Prisoners
Medium7
Dynamic programming, Intervals+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Finding a string with enough inversions
Medium7
Backtracking, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Mutalisk 2
Medium7
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Distinct valid bracket subsequences
Medium7
Dynamic programming, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Food Chain
Medium7
Union-find, Graph
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Card Sets
Medium7
Binary search, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Fox and Card Game
Medium7
Game theory, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Next Special String
Medium7
String, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Selling RNA Strands
Medium7
Trie, String matching
No attempts yet
Time limit
2s
Memory limit
1536 MB
Judgeable
Number Sets
Medium7
Union-find, Number theory+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Alice and Bob's difference game
Medium7
Game theory, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Coloring the Balls
Medium7
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
New Hanoi Tower
Medium7
BFS, Implementation+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Zoo
Medium7
Combinatorics, Dynamic programming
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tree Edit
Medium7
Tree, DFS+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Limited Memory
Medium7
Binary search, Math+2
No attempts yet
Time limit
7s
Memory limit
4 MB
Judgeable
Last three digits of the integer part
Medium7
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Easily limited memory
Medium7
Binary search, Sorting+2
No attempts yet
Time limit
7s
Memory limit
4 MB
Judgeable
Two Weights
Medium7
Shortest path, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Karaoke
Medium7
Dynamic programming, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Turn Game
Medium7
Math, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Decompose into a Product
Medium7
Number theory, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Minho's number game
Medium7
Combinatorics, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hexagonal Board
Medium7
Graph, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Palindrome Walk
Medium7
BFS, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tournament winner placements
Medium7
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Number lock 2
Medium7
Dynamic programming, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cutting Trees
Medium7
Dynamic programming, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
GCD Table
Medium7
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Moving Stones Around a Circle
Medium7
Greedy, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Scrooge Minho 2
Medium7
Tree, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Packing Balls 2
Medium7
Greedy, Math
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Splitting a String
Medium7
Dynamic programming, String+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Secret Lines
Medium7
Sorting, Divide and conquer+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Sum of Matrix Powers
Medium7
Divide and conquer, Matrix+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
A Heap of Heaps
Medium7
Math, Brute force+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hongjun's matrix
Medium7
Binary search, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Colorful Village 3
Medium7
Prefix sum, Sorting+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Chains of Multiples
Medium7
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Secret Mission
Medium7
Dynamic programming, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
ntopia
Medium7
Combinatorics, Math
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
h(n)
Medium7
Number theory, Binary search+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Suffix Array 1
Medium7
String, Sorting+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Painting the Balls
Medium7
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hongjun and Antimatter
Medium7
Dynamic programming, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hongjun and the Tree 2
Medium7
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Teams Creation
Medium7
Combinatorics, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Maximal Sum
Medium7
Sorting, Divide and conquer+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Fancy Antiques
Medium7
Brute force, Bit manipulation+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Greeting Card Envelopes
Medium7
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
K-Inversions
Medium7
Divide and conquer, String+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Laser Game
Medium7
Geometry, Graph+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Funfair
Medium7
Dynamic programming, Sorting+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cafebazaar
Medium7
Graph, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Fibonacci Sequence
Medium7
Math, Matrix+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Brocard Point
Medium7
Geometry, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Delete Files
Medium7
Dynamic programming, Geometry+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Speedrun
Medium7
Probability, Dynamic programming
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Flowers
Medium7
Math, Greedy+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Cookie Counter
Medium7
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Rock Paper Scissors Ranking
Medium7
Probability, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Starlight Falls
Medium7
Geometry, Intervals+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Special Unit CH
Medium7
Simulation, Implementation
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Greedy Coin Exchange
Medium7
Greedy, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Fairies' Sorcery
Medium7
Simulation, Implementation
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Jolly Jelly Jiffy
Medium7
Stack, Topological sort+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Masonry Bridge
Medium7
Graph, Minimum spanning tree+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Knapsack in a Globalized World
Medium7
Number theory, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
One-Way Roads
Medium7
Graph, Greedy
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Common Knowledge
Medium7
Combinatorics, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Routing
Medium7
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The Sadness of Division
Medium7
Graph, Minimum spanning tree+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Crime Party
Medium7
Binary search, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Xor of Subset Sums
Medium7
Bit manipulation, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Ability
Medium7
Probability, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Bits
Medium7
Probability, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cards
Medium7
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tree
Medium7
Combinatorics, Union-find+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Bracelets
Medium7
Combinatorics, Number theory+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Kangaroo
Medium7
Dynamic programming, Combinatorics
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Bracket Match
Medium7
Stack, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Light Up
Medium7
Backtracking, Brute force+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Reading the stone slab
Medium7
Dynamic programming, Segment tree+1
No attempts yet
Time limit
4s
Memory limit
256 MB
Judgeable
Password
Medium7
Array, String matching+1
No attempts yet
Time limit
4s
Memory limit
256 MB
Judgeable
Fish
Medium7
Prefix sum, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Bitcoin Mining Fields
Medium7
Geometry, Math
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Celtic Symmetry
Medium7
Geometry, Hash map+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sum of matrix powers
Medium7
Divide and conquer, Matrix+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Holiday Roads
Medium7
Tree, Probability+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Lottery interest
Medium7
Probability, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cutting down trees
Medium7
Greedy, Sorting
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Suffix array 2
Medium7
String, Sorting+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Birthday Cake
Medium7
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Longest palindromic substring
Medium7
String, Binary search+1
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
3D Printing
Medium7
Graph, BFS+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Deciphering Characters
Medium7
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Arcade!
Medium7
Probability, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Gas Stations
Medium7
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Frog
Medium7
Shortest path, Geometry+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Aurora BorealisGiven sightings at distinct times and positions, find the minimum cloud length so a unit-speed interval can cover every sighting.	Medium7	GeometryBinary search+1	No attempts yet	1s	1024 MB	Judgeable
Bribing the PrisonersRelease Q prisoners from a row of P cells in the order that minimizes bribes paid to neighbors reached by the news. Find that minimum total cost.	Medium7	Dynamic programmingIntervals+1	No attempts yet	2s	512 MB	Judgeable
Finding a string with enough inversionsFind the lexicographically smallest permutation of the first N lowercase letters with at least V inversions that is not smaller than the given string S.	Medium7	BacktrackingCombinatorics+1	No attempts yet	2s	512 MB	Judgeable
Mutalisk 2Given up to 20 SCVs with health, each attack deals 9, 3, and 1 damage to three distinct SCVs; find the minimum number of attacks to destroy all of them.	Medium7	Dynamic programmingBit manipulation+1	No attempts yet	2s	512 MB	Judgeable
Distinct valid bracket subsequencesCount distinct non-empty balanced bracket strings that appear as subsequences of a given bracket string of length at most 100, modulo 1,000,000,007.	Medium7	Dynamic programmingString+2	No attempts yet	2s	512 MB	Judgeable
Food ChainCount records that are invalid or contradict earlier records, treating same-kind and eats relations consistently.	Medium7	Union-findGraph	No attempts yet	2s	512 MB	Judgeable
Card SetsGiven counts of N card types and a pile of jokers, find the maximum number of decks, where each deck is either one card of every type or one card of every type but one plus a joker.	Medium7	Binary searchGreedy+2	No attempts yet	2s	512 MB	Judgeable
Fox and Card GameTwo players alternately take the top (Ciel) or bottom (Jiro) card of one of n piles; find both optimal final scores.	Medium7	Game theoryGreedy+2	No attempts yet	2s	512 MB	Judgeable
Next Special StringGiven a binary special string (each split satisfies U < V), find the next special string of the same length in lexicographic order, or -1 if none exists.	Medium7	StringGreedy+2	No attempts yet	2s	512 MB	Judgeable
Selling RNA StrandsFor each query pair P, Q, count how many dictionary strings start with P and end with Q, where the prefix and suffix may overlap.	Medium7	TrieString matching	No attempts yet	2s	1536 MB	Judgeable
Number SetsCount the connected components formed when numbers A through B are merged whenever they share a prime factor at least P.	Medium7	Union-findNumber theory+1	No attempts yet	2s	512 MB	Judgeable
Alice and Bob's difference gameTwo players alternately add the absolute difference of two set elements when that difference is not already present; determine the winner under optimal play.	Medium7	Game theoryMath+2	No attempts yet	2s	512 MB	Judgeable
Coloring the BallsCount the sequences formed by drawing all balls from a box where the last ball of color 1 appears before the last of color 2, and so on.	Medium7	Dynamic programmingCombinatorics+1	No attempts yet	2s	512 MB	Judgeable
New Hanoi TowerGiven three rods with up to 10 labeled disks, find the minimum number of moves to sort them so each rod holds only its matching disk type.	Medium7	BFSImplementation+2	No attempts yet	5s	512 MB	Judgeable
ZooCount assignments of N animals to two kinds so that the reported same-kind taller counts can be realized by some ordering of distinct heights.	Medium7	CombinatoricsDynamic programming	No attempts yet	2s	512 MB	Judgeable
Tree EditCut one weighted edge of a tree and reattach it elsewhere with the same weight; find the maximum possible diameter.	Medium7	TreeDFS+1	No attempts yet	2s	512 MB	Judgeable
Limited MemoryGenerate a huge pseudorandom array with a linear recurrence and answer many order-statistic queries without storing the array.	Medium7	Binary searchMath+2	No attempts yet	7s	4 MB	Judgeable
Last three digits of the integer partFor each n up to 2e9, report the last three digits of the integer part of (3+sqrt(5))^n, zero padded to three digits.	Medium7	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Easily limited memoryFind the q-th smallest elements of a pseudorandom sequence without storing the whole sequence, then print the sum of the answers.	Medium7	Binary searchSorting+2	No attempts yet	7s	4 MB	Judgeable
Two WeightsGiven an undirected graph with two weights per edge, find the path from 0 to 1 minimizing the product of the two total weight sums.	Medium7	Shortest pathGraph+2	No attempts yet	2s	512 MB	Judgeable
KaraokeAssign each note of a sequence to one of two singers so that the total of the absolute pitch jumps within each singer's subsequence is minimized.	Medium7	Dynamic programmingArray+2	No attempts yet	2s	512 MB	Judgeable
Turn GameGiven final scores x and y, decide whether some prefix of 1,2,3,... can be partitioned into two groups summing to x and y, and find the minimum count of terms in Yunho's group.	Medium7	MathGreedy+2	No attempts yet	2s	512 MB	Judgeable
Decompose into a ProductGiven m as a product of n factors (n ≤ 500, each up to 1e9), count ordered n-tuples of positive integers whose product is m, modulo 1e9+9.	Medium7	Number theoryCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Minho's number gameCount integers from 1 to N divisible by at least one of up to 20 given numbers, where duplicates and multiples make plain unions invalid.	Medium7	CombinatoricsNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Hexagonal BoardGiven a subset of cells on an N by N hexagonal board, find the minimum number of colors so adjacent marked cells differ.	Medium7	GraphGreedy+2	No attempts yet	2s	512 MB	Judgeable
Palindrome WalkGiven an undirected labeled graph, find the length of the shortest walk from vertex 0 to vertex 1 whose edge-label string is a palindrome, or -1 if none exists.	Medium7	BFSGraph+2	No attempts yet	2s	512 MB	Judgeable
Tournament winner placementsCount, over all N! seatings of N players in a fixed bracket, how many make each player the champion given a full win/loss table.	Medium7	Dynamic programmingCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Number lock 2Given two equal-length digit strings S and T, find the fewest moves to turn S into T where a move shifts any contiguous block of dials one step up or down modulo 10.	Medium7	Dynamic programmingGreedy+2	No attempts yet	2s	512 MB	Judgeable
Cutting TreesCut at most M trees per evening with distinct machines to exactly D_i meters, and find the minimum total height after T days.	Medium7	Dynamic programmingGreedy+1	No attempts yet	2s	512 MB	Judgeable
GCD TableGiven all N^2 pairwise gcd values of a hidden sequence in random order, recover the sequence.	Medium7	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Moving Stones Around a CircleGiven stone counts a and b on a cycle of N positions, find the minimum number of moves to transform a into b, or report impossibility.	Medium7	GreedyPrefix sum+1	No attempts yet	2s	512 MB	Judgeable
Scrooge Minho 2Given a tree with N cities, place the fewest police stations so that every city and every road is covered, where a station covers its city, its neighbors, and all incident roads.	Medium7	TreeDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Packing Balls 2Given counts of balls in K colors, pack them into boxes of capacity K where each box is all one color or all distinct colors, using as few boxes as possible.	Medium7	GreedyMath	No attempts yet	2s	512 MB	Judgeable
Splitting a StringChoose K non-overlapping substrings of A that also appear in B in the same non-overlapping order, maximizing their total length.	Medium7	Dynamic programmingString+1	No attempts yet	2s	512 MB	Judgeable
Secret LinesSum \|Xa - Xb\| * max(Va, Vb) over all pairs of members with given power and position.	Medium7	SortingDivide and conquer+1	No attempts yet	1s	512 MB	Judgeable
Sum of Matrix PowersGiven an N by N matrix A and K, compute A + A^2 + ... + A^K with all entries reduced modulo M.	Medium7	Divide and conquerMatrix+1	No attempts yet	2s	512 MB	Judgeable
A Heap of HeapsFor every k from 1 to n-1, treat the array as a k-ary heap and count how many nodes are smaller than their parent.	Medium7	MathBrute force+1	No attempts yet	2s	512 MB	Judgeable
Hongjun's matrixGiven sequences A and B of length N, find the K-th smallest value among all N^2 products A_i * B_j.	Medium7	Binary searchSorting+2	No attempts yet	2s	512 MB	Judgeable
Colorful Village 3For each query range of houses, report the highest number of times any single brightness value appears within that range.	Medium7	Prefix sumSorting+1	No attempts yet	5s	512 MB	Judgeable
Chains of MultiplesCount non-decreasing length-L sequences of values from 1 to N where in every pair one value divides the other, modulo 1e9+7.	Medium7	CombinatoricsDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Secret MissionGiven n candidates with talkativeness values, use at most s adjacent swaps to make the sum of the first k values as small as possible.	Medium7	Dynamic programmingGreedy+2	No attempts yet	2s	512 MB	Judgeable
ntopiaCount the number of ways to assign 1, 2, or 3 of three singers to each of S songs so each singer reaches a given song count.	Medium7	CombinatoricsMath	No attempts yet	2s	512 MB	Judgeable
h(n)Given n up to 10^18, find the smallest x with x raised to d(x), its divisor count, equal to n, or -1.	Medium7	Number theoryBinary search+1	No attempts yet	2s	512 MB	Judgeable
Suffix Array 1Given S, decide whether some lexicographically smaller string of the same length has an identical suffix array. Constraints: \|S\| <= 50.	Medium7	StringSorting+1	No attempts yet	2s	512 MB	Judgeable
Painting the BallsGiven M range-painting operations used in order with unknown colors, count how many distinct final black/white ball colorings are possible.	Medium7	Dynamic programmingBit manipulation+1	No attempts yet	2s	512 MB	Judgeable
Hongjun and AntimatterCount contiguous subarrays of length at least 2 that can be split into two disjoint nonempty parts with equal sums, modulo 1e9+7.	Medium7	Dynamic programmingPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
Hongjun and the Tree 2Count the ways to cut edges of a tree so every remaining component has exactly one black vertex, modulo 1e9+7.	Medium7	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
Teams CreationCount the ways to partition n students into exactly k unnumbered teams so that any two teams are separated by a threshold on skill level.	Medium7	CombinatoricsSorting+2	No attempts yet	2s	512 MB	Judgeable
Maximal SumFor each query value b_j, find the maximum sum of a contiguous segment of a whose elements are all at least b_j, or 0 if none exists.	Medium7	SortingDivide and conquer+2	No attempts yet	2s	512 MB	Judgeable
Fancy AntiquesPick at most k shops so that every item can be bought (original or knock-off) at a visited shop, minimizing total price.	Medium7	Brute forceBit manipulation+2	No attempts yet	10s	512 MB	Judgeable
Greeting Card EnvelopesPartition up to 15 card types into at most k groups so the total waste, where each group's waste uses one enclosing envelope sized to the group's max width and max height, is minimized.	Medium7	Dynamic programmingBit manipulation+2	No attempts yet	3s	512 MB	Judgeable
K-InversionsFor every distance k, count pairs (i,j) with i<j, s[i]='B', s[j]='A', and j-i=k, over a string of up to a million characters.	Medium7	Divide and conquerString+2	No attempts yet	10s	512 MB	Judgeable
Laser GameGiven n directed rays and two points s and t, find the minimum number of rays a curve from s to t must cross.	Medium7	GeometryGraph+1	No attempts yet	2s	512 MB	Judgeable
FunfairPick and order k games from n so the expected final money is maximized, then report that value.	Medium7	Dynamic programmingSorting+1	No attempts yet	2s	512 MB	Judgeable
CafebazaarAssign each full-time developer and each critical application to a matching partner while maximizing total payoff, or report -1 if impossible.	Medium7	GraphDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Fibonacci SequenceFor up to 1000 queries, compute the x-th Fibonacci number modulo 10^9, where x can be as large as 2^48.	Medium7	MathMatrix+2	No attempts yet	2s	512 MB	Judgeable
Brocard PointGiven the coordinates of a triangle's vertices in anticlockwise order, compute the coordinates of its Brocard point and print them to five decimal places.	Medium7	GeometryMath+2	No attempts yet	2s	512 MB	Judgeable
Delete FilesGiven a top-aligned list of name boxes with widths, find the minimum number of axis-aligned rectangle selections whose deletions remove all 'y' files and keep all 'n' files.	Medium7	Dynamic programmingGeometry+2	No attempts yet	5s	512 MB	Judgeable
SpeedrunGiven per-road win probabilities, choose checkpoints to save at so the expected time to reach checkpoint n is minimized.	Medium7	ProbabilityDynamic programming	No attempts yet	8s	512 MB	Judgeable
FlowersMinimize Wpw + sum F_ipf_i subject to Wvw_i + F_ivf_i >= th_i, with W,F_i >= 0 and reals allowed.	Medium7	MathGreedy+1	No attempts yet	8s	512 MB	Judgeable
Cookie CounterCount sequences of D days, each amount in [0, X), summing to N, modulo 1e9+7.	Medium7	CombinatoricsDynamic programming+1	No attempts yet	8s	512 MB	Judgeable
Rock Paper Scissors RankingGiven each contestant's probabilities for scissors, rock, and paper, find the probability that contestant 1 finishes in place K of the recursive elimination tournament.	Medium7	ProbabilityDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Starlight FallsGiven two observers' angular-direction and distance-range observations, decide whether a consistent star placement exists and find the maximum number of stars.	Medium7	GeometryIntervals+2	No attempts yet	2s	128 MB	Judgeable
Special Unit CHSimulate a cart moving on a line with agents that board it, are shot, die, and revive, and report the cart's position at each query time.	Medium7	SimulationImplementation	No attempts yet	2s	64 MB	Judgeable
Greedy Coin ExchangeGiven sorted coin denominations starting with 1, decide whether the greedy largest-coin-first method always uses the fewest coins for every amount.	Medium7	GreedyDynamic programming+2	No attempts yet	1s	64 MB	Judgeable
Fairies' SorceryGiven M-1 recorded spells and the final arrangement, find the position and type of one missing spell cast by a specified fairy.	Medium7	SimulationImplementation	No attempts yet	2s	256 MB	Judgeable
Jolly Jelly JiffyCount and lexicographically minimize total orders consistent with the final box state of an insertion-sort-like stacking process and one extra value.	Medium7	StackTopological sort+2	No attempts yet	2s	256 MB	Judgeable
Masonry BridgeGiven a connected undirected graph with edge weights, find the minimum over edge orderings of the earliest time island 1 and island N connect, and the maximum such time.	Medium7	GraphMinimum spanning tree+2	No attempts yet	2s	128 MB	Judgeable
Knapsack in a Globalized WorldWith unlimited copies of n item sizes, decide whether some multiset sums to exactly k, where k can reach 10^18.	Medium7	Number theoryDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
One-Way RoadsOrient every edge of an undirected graph so that the maximum number of edges entering any vertex is as small as possible.	Medium7	GraphGreedy	No attempts yet	2s	512 MB	Judgeable
Common KnowledgeCount pairs of n-digit scores where each player, seeing only half of both boards, can deduce all 2n digits.	Medium7	CombinatoricsBit manipulation+1	No attempts yet	2s	512 MB	Judgeable
RoutingFind the minimum total processing time for a message from server 1 to server n, where each server blocks forwarding certain (previous server, next server) pairs and revisiting servers adds their cost again.	Medium7	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
The Sadness of DivisionSplit N members into two camps, respecting fixed members, to minimize the total weight of pairs split across camps, and output the lexicographically smallest camp A.	Medium7	GraphMinimum spanning tree+2	No attempts yet	1s	512 MB	Judgeable
Crime PartyEach suspect has two friends with thresholds; pick the smallest cost K so every suspect gets at least one friend whose threshold is at most K, with each person defending at most one suspect.	Medium7	Binary searchGreedy+2	No attempts yet	1s	512 MB	Judgeable
Xor of Subset SumsGiven n integers, find the XOR of the sums of all 2^n subsets.	Medium7	Bit manipulationCombinatorics+1	No attempts yet	1s	512 MB	Judgeable
AbilityCompute the expected damage of one attack where abilities are tried in a uniformly random order without replacement until one fires, and output the fraction modulo 1e9+7.	Medium7	ProbabilityMath+2	No attempts yet	2s	512 MB	Judgeable
BitsGiven N bits and K odd random index toggles per operation after sorting, compute for each starting zero count the expected number of operations to reach all ones.	Medium7	ProbabilityDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
CardsFind the probability that L random packs of N equally likely card types meet every demand D_i, output as a fraction mod 1e9+7.	Medium7	Dynamic programmingCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
TreeCount labelled trees on N vertices that contain all M given edges, modulo 1e9+7, with N up to 1e9.	Medium7	CombinatoricsUnion-find+2	No attempts yet	1s	512 MB	Judgeable
BraceletsCount the distinct bracelets (necklaces up to rotation and reflection) with at most N beads over K colors, modulo 1e9+7.	Medium7	CombinatoricsNumber theory+2	No attempts yet	1s	512 MB	Judgeable
KangarooCount the alternating-direction routes by which a kangaroo visits every cell of a row exactly once, starting at cs and ending at cf.	Medium7	Dynamic programmingCombinatorics	No attempts yet	2s	512 MB	Judgeable
Bracket MatchGiven a lowercase string S, find the lexicographically smallest matching bracket sequence, or print -1 if none exists.	Medium7	StackGreedy+1	No attempts yet	2s	512 MB	Judgeable
Light UpPlace bulbs on white cells of an N by N Light Up board so every white cell is lit and each numbered black cell has the required count of adjacent bulbs, choosing the lexicographically smallest solution.	Medium7	BacktrackingBrute force+2	No attempts yet	2s	256 MB	Judgeable
Reading the stone slabAfter each range replacement on a string, count the number of subsequences equal to a given name of length at most 5, modulo 1e9+7.	Medium7	Dynamic programmingSegment tree+1	No attempts yet	4s	256 MB	Judgeable
PasswordGiven finishes over N years, find the lexicographically largest password substring allowed by rules and count its occurrences.	Medium7	ArrayString matching+1	No attempts yet	4s	256 MB	Judgeable
FishCount contiguous subarrays whose sum is at least K.	Medium7	Prefix sumDivide and conquer+2	No attempts yet	1s	64 MB	Judgeable
Bitcoin Mining FieldsGiven up to a million integer points, find the largest squared Euclidean distance between any two of them and print it.	Medium7	GeometryMath	No attempts yet	1s	64 MB	Judgeable
Celtic SymmetryGiven up to 1000 distinct integer points in the plane, count the distinct lines of symmetry of the set.	Medium7	GeometryHash map+2	No attempts yet	2s	512 MB	Judgeable
Sum of matrix powersCompute A + A^2 + ... + A^B for an N by N matrix A, with B up to 1e11, printing every entry modulo 1000.	Medium7	Divide and conquerMatrix+1	No attempts yet	2s	512 MB	Judgeable
Holiday RoadsOn a tree, each of M families picks one of the other N-1 cities uniformly and independently; find the expected number of roads used by every family.	Medium7	TreeProbability+1	No attempts yet	2s	512 MB	Judgeable
Lottery interestCompute Kangho's expected balance after C weekly lottery drawings, where each ticket (one per won) is equally likely to win J, and print the exact fraction.	Medium7	ProbabilityMath+1	No attempts yet	2s	512 MB	Judgeable
Cutting down treesCut every tree to height 0; each recharge costs b_i where i is the largest index already felled, and you must minimize total cost given increasing a_i and decreasing b_i.	Medium7	GreedySorting	No attempts yet	2s	512 MB	Judgeable
Suffix array 2Sort all suffixes of a string lexicographically and output the starting index of each suffix in sorted order.	Medium7	StringSorting+1	No attempts yet	2s	512 MB	Judgeable
Birthday CakeCount proper colorings of a cycle with N vertices and K colors, plus a center, as vertices are forced to differ from the center over time.	Medium7	Dynamic programmingCombinatorics+1	No attempts yet	2s	256 MB	Judgeable
Longest palindromic substringFind the length of the longest contiguous substring of S that reads the same forwards and backwards.	Medium7	StringBinary search+1	No attempts yet	0.5s	512 MB	Judgeable
3D PrintingSelect exactly k of n non-overlapping unit-direction cubes whose grid adjacency graph is connected, minimizing the union's surface area.	Medium7	GraphBFS+1	No attempts yet	2s	512 MB	Judgeable
Deciphering CharactersDecide whether two binary images represent the same character by comparing their connected components and the containment (surrounds) relations among them.	Medium7	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
Arcade!Given a triangular grid of holes with per-hole bounce probabilities and payouts, compute the expected payout of one dropped ball.	Medium7	ProbabilityDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Gas StationsIn a connected undirected weighted graph, buy fuel at cities with given prices to travel from city 1 to city N at minimum total cost, with no tank limit.	Medium7	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
FrogFind the minimum total squared jump cost for a frog to travel from the lower bank to the upper bank across axis-aligned logs.	Medium7	Shortest pathGeometry+2	No attempts yet	1s	512 MB	Judgeable