Problems

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Total results29,417 problems

A and B
Medium6
Greedy, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Building a Graph
Medium6
Tree, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Favorite Array
Medium6
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Paths of length K
Medium6
Matrix, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tidying up
Medium6
Geometry, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Ordinary Knapsack 2
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Collecting stars
Medium6
Greedy, Sorting+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Building Heights
Medium6
Greedy, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Karaoke 2
Medium6
Dynamic programming, Greedy
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Fun box packing
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Robot Movement
Medium6
Dynamic programming, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Number Lock
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Parade
Medium6
Graph, Shortest path+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Visits
Medium6
Graph, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Time Travel and Multiset
Medium6
Dynamic programming, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Trisle
Medium6
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Folding Paper
Medium6
Math, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Packing Balls
Medium6
Greedy, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Set Definition
Medium6
Heap, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Colorful Village 2
Medium6
Array, Binary search+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Stock Charts
Medium6
Geometry, Intervals+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tree Country
Medium6
Dynamic programming, Tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Acka
Medium6
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hongjun and balanced tables
Medium6
Combinatorics, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Happy Cow
Medium6
Dynamic programming, Intervals
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Happy Tree
Medium6
Tree, DFS+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Candy Density
Medium6
Math, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
A Dark Flame Dragon Sleeps in My Left Hand
Medium6
Tree, DFS+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Unusual Number
Medium6
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Good Sets
Medium6
Bit manipulation, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sum of subtree sizes
Medium6
Tree, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Chain Detonation
Medium6
Greedy, Intervals+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Rectangle and Squares
Medium6
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Zeroes and Ones
Medium6
Math, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Mountain Scenes
Medium6
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Box pushing robot
Medium6
BFS, Graph
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
History Cleanable DFA
Medium6
Graph, BFS+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
RATS Sequence
Medium6
Simulation, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
M and A
Medium6
Dynamic programming, String
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Line Gimmick
Medium6
Greedy, Implementation+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Shifting a Matrix
Medium6
Simulation, Implementation+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Donut Decoration
Medium6
Intervals, Sorting+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Points and Lines
Medium6
Implementation, Math+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Corrupt Election
Medium6
Brute force, Implementation+1
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Matrix Cipher
Medium6
Math, Simulation
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Model Railroad
Medium6
Minimum spanning tree, Union-find+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Maximum Clique of an Interval Graph
Medium6
Sorting, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Happy Kindergarten
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Dice Game Win Probability
Medium6
Dynamic programming, Probability+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Robot
Medium6
Probability, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Router 6
Medium6
Graph, Implementation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Pizza Placement
Medium6
Geometry, Math+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Professor KCM's Question
Medium6
Number theory, Math+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Binary Roads
Medium6
Graph, BFS+1
No attempts yet
Time limit
3s
Memory limit
64 MB
Judgeable
Divisors Again
Medium6
Number theory, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Domain clusters
Medium6
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sum of digits
Medium6
Math, Implementation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Rabbit Movement
Medium6
Simulation, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Turned away from class
Medium6
Math, Implementation
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Dice and Candies
Medium6
Dynamic programming, Probability+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Torus Sea
Medium6
Probability, Graph+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Flipping Coins
Medium6
Probability, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Kangho's Invitations
Medium6
Probability, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cutting a String
Medium6
Dynamic programming, Intervals
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
OR Score of a Sequence
Medium6
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sequence Sorting Queries
Medium6
Sorting, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Prefix and Suffix
Medium6
String, Hash map+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Product Sum Queries
Medium6
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Bamboo Blossoms
Medium6
Number theory, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Daruma Otoshi
Medium6
Dynamic programming, Intervals
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Big Truck
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Brackets
Medium6
Greedy, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Inverse factorial
Medium6
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Nine Packs
Medium6
Dynamic programming
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Unusual Darts
Medium6
Geometry, Brute force+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Obstacle Course Run
Medium6
Geometry, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tree
Medium6
Union-find, Tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Arccosine is a matter of faith
Medium6
Math, Implementation
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
A Typo in Floyd
Medium6
Shortest path, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Message Passing
Medium6
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Railroad
Medium6
Sorting, Sliding window+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Chess Tournament
Medium6
Union-find, Graph+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Lost in the Woods
Medium6
Graph, Probability+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
The sun goes down...
Medium6
Geometry, Brute force+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Bless You Autocorrect!
Medium6
Trie, Dynamic programming+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Daydreaming Stockbroker
Medium6
Greedy, Simulation
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Cocktail Shaker Sort
Medium6
Array, Simulation+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
The Escape
Medium6
BFS, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Carrot Farm
Medium6
Intervals, Tree+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Clique Graph Shortest Path Sum
Medium6
Graph, BFS+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Minimum turns on the number screws
Medium6
Greedy, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
School Tour
Medium6
Minimum spanning tree, Union-find+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Kookmin Land
Medium6
Math, Greedy+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Maximum bipartite matching
Medium6
Graph, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Array Sum
Medium6
Sorting, Hash map+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Coin Exchange
Medium6
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Iterated Sums
Medium6
Combinatorics, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Circles tangent to a line
Medium6
Brute force, Geometry+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Magic Trees
Medium6
Graph, Greedy
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Go
Medium6
Graph, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
A and BGiven two strings of A and B, decide whether S can be turned into T using only: append A, or reverse then append B.	Medium6	GreedyString+2	No attempts yet	2s	512 MB	Judgeable
Building a GraphBuild a connected graph (tree) with N nodes and N-1 edges, where each node's score depends on its degree, and maximize the total score.	Medium6	TreeDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Favorite ArrayCount length-N arrays with entries from 1 to K where no earlier element is a larger multiple of the next.	Medium6	Dynamic programmingCombinatorics+1	No attempts yet	2s	512 MB	Judgeable
Paths of length KCount the number of length-K walks in a directed graph given its adjacency matrix, where K can be as large as 10^9, and output the count modulo 10^9+7.	Medium6	MatrixGraph+2	No attempts yet	2s	512 MB	Judgeable
Tidying upPlace N points so the configuration is symmetric about the y-axis with equal multiplicities; minimize the total Euclidean distance moved.	Medium6	GeometryGreedy+2	No attempts yet	2s	512 MB	Judgeable
Ordinary Knapsack 2Given N item types with weight, satisfaction, and a copy count, choose a multiset whose total weight is at most M and whose total satisfaction is largest.	Medium6	Dynamic programmingGreedy+2	No attempts yet	1s	512 MB	Judgeable
Collecting starsEach stage yields up to 2 stars when cleared with enough stars in hand; find the minimum number of clears to collect all 2N stars or report it is impossible.	Medium6	GreedySorting+1	No attempts yet	2s	512 MB	Judgeable
Building HeightsWith building 1 at height 0, adjacent heights differing by at most K, and M caps, find the maximum achievable height of any building.	Medium6	GreedyImplementation+2	No attempts yet	2s	512 MB	Judgeable
Karaoke 2Assign the unclaimed middle pitches to one of two singers to minimize how many times the microphone changes hands across the song.	Medium6	Dynamic programmingGreedy	No attempts yet	2s	512 MB	Judgeable
Fun box packingGiven N box sizes, nest a box inside another when the outer size is at least twice the inner, each box holds at most one, and minimize the number of visible (unnested) boxes.	Medium6	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
Robot MovementA robot walks on an infinite grid following a fixed-length string of U, D, L, R moves. Change at most M characters to maximize how many times it returns to the origin.	Medium6	Dynamic programmingString+2	No attempts yet	2s	512 MB	Judgeable
Number LockGiven two equal-length digit strings S and T, find the minimum number of turns where each turn adds 1 or subtracts 1 (mod 10) to every dial in some contiguous range.	Medium6	Dynamic programmingGreedy+2	No attempts yet	2s	512 MB	Judgeable
ParadeFor each road, count the pairs of intersections whose shortest distance grows when that road is removed from the graph.	Medium6	GraphShortest path+1	No attempts yet	5s	512 MB	Judgeable
VisitsGiven an R by C grid and an integer K, decide whether a walk exists that visits every cell exactly K times, starting and ending anywhere.	Medium6	GraphGreedy+1	No attempts yet	2s	512 MB	Judgeable
Time Travel and MultisetProcess insert, delete, and count operations on a time-indexed multiset, where each value's count at time t depends on prior operations with time at most t.	Medium6	Dynamic programmingBinary search+2	No attempts yet	2s	512 MB	Judgeable
TrislePartition N powers into three nonempty groups to maximize the sum of the three XOR values.	Medium6	Dynamic programmingBit manipulation+1	No attempts yet	2s	512 MB	Judgeable
Folding PaperStarting from a W by H sheet, each fold keeps the longer of the two pieces along one axis; find the minimum number of folds that yields area exactly A, or -1.	Medium6	MathGreedy+2	No attempts yet	2s	512 MB	Judgeable
Packing BallsGiven counts of red, green, and blue balls, pack them all into minimum boxes where each box holds 1 to 3 balls of one color or three distinct colors.	Medium6	GreedyMath+2	No attempts yet	2s	512 MB	Judgeable
Set DefinitionFind the N-th smallest number in the set generated from 1 by repeatedly applying x -> 2x+1 and x -> 3x+1.	Medium6	HeapMath+1	No attempts yet	2s	512 MB	Judgeable
Colorful Village 2For each query range in a nondecreasing brightness array, report how many times the most frequent value appears.	Medium6	ArrayBinary search+1	No attempts yet	2s	512 MB	Judgeable
Stock ChartsGiven N piecewise-linear price graphs over K time points, find the minimum number of charts so that no two graphs on a chart intersect.	Medium6	GeometryIntervals+1	No attempts yet	2s	512 MB	Judgeable
Tree CountryCount the subsets of K vertices in a tree that form a connected subtree, modulo 1e9+7.	Medium6	Dynamic programmingTree+2	No attempts yet	2s	512 MB	Judgeable
AckaCount the ways to assign each of S songs to a nonempty subset of three singers so that the three singers get exactly D, K, and H songs.	Medium6	CombinatoricsDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Hongjun and balanced tablesCount the ways to fill a 3-by-C grid with nonnegative integers so that every triple of cells satisfying a + c = 2b sums to S.	Medium6	CombinatoricsMath+2	No attempts yet	2s	512 MB	Judgeable
Happy CowRemove portions from either end of a row over N days; on day d a portion with value H gives H times d. Maximize total happiness.	Medium6	Dynamic programmingIntervals	No attempts yet	2s	512 MB	Judgeable
Happy TreeFind the minimum number of leaves to remove so that no remaining vertex has a descendant whose path distance exceeds that descendant's value.	Medium6	TreeDFS+1	No attempts yet	2s	512 MB	Judgeable
Candy DensityChoose a candy density d minimizing the sum of \|W_i - d*C_i\|, and print the minimum as an exact reduced fraction.	Medium6	MathGreedy+2	No attempts yet	2s	512 MB	Judgeable
A Dark Flame Dragon Sleeps in My Left HandFor each node in a weighted tree, find the distance to the farthest other node (the tree's eccentricity).	Medium6	TreeDFS+1	No attempts yet	2s	512 MB	Judgeable
Unusual NumberGiven digit count a and multiplier b, find the smallest a-digit number whose last digit moved to the front equals b times the number, or report Impossible.	Medium6	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Good SetsCount nonempty subsets of {1,...,N} whose decimal digits, pooled together, use each digit 0-9 at most once.	Medium6	Bit manipulationCombinatorics+1	No attempts yet	2s	512 MB	Judgeable
Sum of subtree sizesCount all connected subgraphs of a tree and output the sum of their vertex counts modulo 1e9+7.	Medium6	TreeDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Chain DetonationPlace one extra bomb past the last one with unlimited power to destroy as many not-yet-detonated bombs, minimizing the duds among the original bombs.	Medium6	GreedyIntervals+1	No attempts yet	2s	512 MB	Judgeable
Rectangle and SquaresGiven target area AB and a square size C, find the rectangle of side C that is closest in area to AB, breaking ties toward the smaller area.	Medium6	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Zeroes and OnesInvert two adjacent characters of either of two binary strings to make them equal, using the fewest operations, or report -1.	Medium6	MathString+2	No attempts yet	2s	512 MB	Judgeable
Mountain ScenesCount vectors of w heights in [0,h] whose sum is at most n and which are not all equal, modulo 1e9+7.	Medium6	Dynamic programmingCombinatorics+2	No attempts yet	5s	512 MB	Judgeable
Box pushing robotCount the grid cells a box can reach when a robot walking on free cells can push it one step at a time from its start.	Medium6	BFSGraph	No attempts yet	4s	512 MB	Judgeable
History Cleanable DFAGiven a binary DFA, decide whether some input string drives every state to one common state.	Medium6	GraphBFS+1	No attempts yet	2s	512 MB	Judgeable
RATS SequenceSimulate a RATS sequence term by term for up to M steps, detecting the first term that repeats an earlier value or first takes the chain form 12334444 or 55667777.	Medium6	SimulationImplementation+2	No attempts yet	2s	512 MB	Judgeable
M and ADecide whether S can be interleaved character by character from a subsequence of S and a subsequence of T, both of the same length as S.	Medium6	Dynamic programmingString	No attempts yet	5s	512 MB	Judgeable
Line GimmickGiven a row of panels with arrows, pick a starting panel and count how many panels can disappear if the walk is chosen to maximize that count.	Medium6	GreedyImplementation+2	No attempts yet	5s	512 MB	Judgeable
Shifting a MatrixParse a compressed shift-operation string with nested repetitions, apply the row and column rotations to an N by N matrix, and print the result.	Medium6	SimulationImplementation+2	No attempts yet	5s	512 MB	Judgeable
Donut DecorationGiven N donuts and T interval operations each applying a task number, count donuts whose operations form tasks 1..K in order.	Medium6	IntervalsSorting+1	No attempts yet	5s	512 MB	Judgeable
Points and LinesParse an expression of points and lines joined by @, evaluate geometric operations, and print the resulting point rounded to 8 decimals.	Medium6	ImplementationMath+1	No attempts yet	8s	512 MB	Judgeable
Corrupt ElectionCount pairs (X, Y) such that voiding every voter with A_i>=X or B_i>=X or A_i+B_i>=Y leaves Cheki strictly ahead of Chaka.	Medium6	Brute forceImplementation+1	No attempts yet	1s	64 MB	Judgeable
Matrix CipherGiven the 2x2 matrix formed by reading a bitstring and right-multiplying by one of the two elementary matrices per bit, recover the bitstring.	Medium6	MathSimulation	No attempts yet	2s	512 MB	Judgeable
Model RailroadDecide if the existing tracks can be replaced, within the same total length budget, so that all stations become connected.	Medium6	Minimum spanning treeUnion-find+1	No attempts yet	2s	512 MB	Judgeable
Maximum Clique of an Interval GraphGiven N intervals, find a largest set of pairwise overlapping intervals, and output its size plus the vertex indices in lexicographically smallest order.	Medium6	SortingGreedy+2	No attempts yet	1s	512 MB	Judgeable
Happy KindergartenSplit a non-decreasing array of heights into K contiguous groups to minimize the sum of each group's max-minus-min.	Medium6	Dynamic programmingGreedy+2	No attempts yet	1s	512 MB	Judgeable
Dice Game Win ProbabilityA token moves on states 0 to N, stepping down with probability Q/P and up otherwise; find the probability of ending at N and print it modulo 1e9+7 as a reduced fraction.	Medium6	Dynamic programmingProbability+1	No attempts yet	1s	512 MB	Judgeable
RobotCompute the expected squared distance from the origin after a robot takes N probabilistic left, straight, or right moves, and print it as a fraction modulo 1e9+7.	Medium6	ProbabilityMath+1	No attempts yet	1s	512 MB	Judgeable
Router 6Construct a layered routing network of collectors, hubs, and distributors connecting N inputs to N outputs within given connection and power limits.	Medium6	GraphImplementation+1	No attempts yet	2s	512 MB	Judgeable
Pizza PlacementPlace circles tangent to two legs of a right triangle without overlapping earlier ones; report the area of the k-th largest.	Medium6	GeometryMath+1	No attempts yet	1s	256 MB	Judgeable
Professor KCM's QuestionGiven natural numbers, repeatedly replace two with their gcd and lcm, and maximize the largest number ever on the board. Print that maximum modulo 1e9+7.	Medium6	Number theoryMath+1	No attempts yet	3s	256 MB	Judgeable
Binary RoadsAli's carried value flips after every road, so each edge is usable only when its label matches his value; find the shortest 0-1 walk from node 0 to node N-1, or -1.	Medium6	GraphBFS+1	No attempts yet	3s	64 MB	Judgeable
Divisors AgainFor each of up to 10 ranges of at most 1001 integers, find the number in [L, U] with the most divisors.	Medium6	Number theoryPrefix sum+1	No attempts yet	2s	512 MB	Judgeable
Domain clustersGiven a directed graph of domains, find the size of the largest set in which every domain can reach every other domain.	Medium6	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
Sum of digitsSum every digit that appears in the decimal representations of 0 through n, where n can be as large as 10^16.	Medium6	MathImplementation+1	No attempts yet	2s	512 MB	Judgeable
Rabbit MovementGiven a colored board of at most 17 cells, simulate rabbits that move, collide, and shrink the board, then compute the expected number left from a uniformly random start.	Medium6	SimulationCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Turned away from classGiven Hyobin's random arrival time in [D,E] and Yeongseon's fixed wait-walk cycle, compute the probability that Yeongseon is C or more seconds late.	Medium6	MathImplementation	No attempts yet	2s	512 MB	Judgeable
Dice and CandiesFind the expected number of throws of a fair six-sided die until the running sum reaches at least N, and print the value to six decimals.	Medium6	Dynamic programmingProbability+2	No attempts yet	2s	512 MB	Judgeable
Torus SeaOn a torus of size N by M, a random walk moves diagonally each day; find the expected number of days to first reach (x, y), or -1 if unreachable.	Medium6	ProbabilityGraph+1	No attempts yet	2s	512 MB	Judgeable
Flipping CoinsEach step flips a uniformly random set of A_i coins; find the expected number of heads after all K steps.	Medium6	ProbabilityDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Kangho's InvitationsGiven each friend's single disliked friend, find the expected number of friends who accept when a uniformly random invitation order is used.	Medium6	ProbabilityMath+1	No attempts yet	2s	512 MB	Judgeable
Cutting a StringGiven cut positions on a string of length N, find the order of cuts that minimizes the total cost, where each cut of a piece of length L costs L.	Medium6	Dynamic programmingIntervals	No attempts yet	2s	512 MB	Judgeable
OR Score of a SequenceSplit the array into K contiguous non-empty groups and maximize the sum of each group's bitwise OR.	Medium6	Dynamic programmingBit manipulation+1	No attempts yet	2s	512 MB	Judgeable
Sequence Sorting QueriesGiven a sequence, each query sorts it, adds X to the elements at positions L through R, and sorts again; output the final sorted sequence.	Medium6	SortingImplementation+2	No attempts yet	1s	128 MB	Judgeable
Prefix and SuffixCount the distinct substrings of S that both start with string A and end with string B, where A and B may overlap within a substring.	Medium6	StringHash map+1	No attempts yet	2s	512 MB	Judgeable
Product Sum QueriesFor each query K, sum the products of all K-element subsets of A, counting positions separately, modulo 100003.	Medium6	Dynamic programmingCombinatorics+1	No attempts yet	2s	512 MB	Judgeable
Bamboo BlossomsChoose n lifetimes of at least m years, one per block, so the first year with no blossom in any block is as late as possible; report that year.	Medium6	Number theoryGreedy+1	No attempts yet	2s	512 MB	Judgeable
Daruma OtoshiGiven a stack of weighted blocks, remove adjacent pairs whose weights differ by at most 1, in any order, to maximize the total removed.	Medium6	Dynamic programmingIntervals	No attempts yet	2s	512 MB	Judgeable
Big TruckFind a shortest path from node 1 to node n in an undirected weighted graph, and among all shortest paths maximize the total items collected at visited nodes.	Medium6	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
BracketsGiven a bracket string, decide whether flipping the brackets in at most one contiguous segment can turn the whole string into a balanced, valid bracket sequence.	Medium6	GreedyPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
Inverse factorialGiven a huge number that is some factorial n!, recover the integer n. The input can have up to a million digits.	Medium6	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Nine PacksGiven multiset pile sizes of hotdog and bun packs, buy the fewest total packs so the chosen hotdogs and buns sum to the same number.	Medium6	Dynamic programming	No attempts yet	2s	512 MB	Judgeable
Unusual DartsGiven seven dart positions forming a simple polygon in some unknown order and the win probability of a random three-dart throw, find the dart order that matches it.	Medium6	GeometryBrute force+1	No attempts yet	2s	512 MB	Judgeable
Obstacle Course RunGiven vertical wall segments, find the shortest eastbound route from a start point to a finish line and list the y coordinates of all distinct endpoints of shortest routes.	Medium6	GeometryGraph+2	No attempts yet	2s	512 MB	Judgeable
TreeGiven a rooted tree, process a mix of edge deletions and connectivity queries in order, answering YES or NO for each query.	Medium6	Union-findTree+2	No attempts yet	2s	512 MB	Judgeable
Arccosine is a matter of faithPrint up to 100000 integers whose sum is between -100 and 100, so that adding each value divided by 100 in floating point makes acos differ from the exact result by over 0.001.	Medium6	MathImplementation	No attempts yet	2s	512 MB	Judgeable
A Typo in FloydCount ordered pairs whose shortest-path values differ when Floyd's outer loop skips vertex N as an intermediate.	Medium6	Shortest pathDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Message PassingCount the telephone calls made at time t when each informed employee calls d new people over the next d time units, modulo 31991.	Medium6	Dynamic programmingCombinatorics+1	No attempts yet	1s	512 MB	Judgeable
RailroadGiven n intervals with distinct endpoint positions, find the maximum number of intervals fully contained in some segment of fixed length d.	Medium6	SortingSliding window+2	No attempts yet	1s	512 MB	Judgeable
Chess TournamentGiven reported chess results, decide whether some assignment of skill levels makes all results true, where equal skills draw and higher skill always wins.	Medium6	Union-findGraph+1	No attempts yet	5s	512 MB	Judgeable
Lost in the WoodsGiven an undirected graph, find the expected number of random-walk steps from node 0 until node N-1 is reached.	Medium6	GraphProbability+2	No attempts yet	5s	512 MB	Judgeable
The sun goes down...Given up to 100000 distinct points in the plane, decide whether two straight lines can cover all of them.	Medium6	GeometryBrute force+2	No attempts yet	5s	512 MB	Judgeable
Bless You Autocorrect!For each target word, compute the fewest keystrokes using letter keys, tab (autocomplete to the most common dictionary word matching the typed prefix), and backspace.	Medium6	TrieDynamic programming+1	No attempts yet	3s	512 MB	Judgeable
Daydreaming StockbrokerGiven daily stock prices and a 100000 share cap, find the maximum money starting from $100 when whole shares can be bought and sold.	Medium6	GreedySimulation	No attempts yet	1s	512 MB	Judgeable
Cocktail Shaker SortSimulate cocktail shaker sort on a permutation and report the number of swaps performed in each of the N steps.	Medium6	ArraySimulation+1	No attempts yet	1s	512 MB	Judgeable
The EscapeIn a three-floor grid dungeon with walls, ladders, and one-way trapdoors linking labelled squares, find the minimum time to reach the exit ladder on floor 1.	Medium6	BFSGraph+2	No attempts yet	2s	512 MB	Judgeable
Carrot FarmMaintain a set of disjoint planted intervals under plant and harvest operations; after each, report the empty or planted area directly left and right of the affected span. Each area is (number of columns) times L.	Medium6	IntervalsTree+2	No attempts yet	3s	512 MB	Judgeable
Clique Graph Shortest Path SumA graph is given as a union of K cliques on overlapping vertex lists; sum the shortest path lengths over all vertex pairs.	Medium6	GraphBFS+1	No attempts yet	2s	512 MB	Judgeable
Minimum turns on the number screwsEach left turn on a screw also rotates every screw below it; find the fewest total notches to reach the wanted digit string.	Medium6	GreedyMath	No attempts yet	1s	128 MB	Judgeable
School TourChoose a spanning tree of the graph rooted at the entrance that contains the fixed edge to building 1, find the min and max possible number of uphill edges among its edges, and print (max)^2 - (min)^2.	Medium6	Minimum spanning treeUnion-find+2	No attempts yet	1s	256 MB	Judgeable
Kookmin LandGiven four integer points, find the integer side length L>=1 of an axis-aligned square centered at the origin minimizing the total Manhattan distance to assign each point to a distinct vertex.	Medium6	MathGreedy+1	No attempts yet	2s	128 MB	Judgeable
Maximum bipartite matchingGiven bipartite part sizes n1, n2, matching size ans, and minimum degree d, find the maximum possible number of edges, or -1 if impossible.	Medium6	GraphGreedy+2	No attempts yet	2s	512 MB	Judgeable
Array SumReorder two arrays to make some sum value repeat as often as possible; report the maximum repeat count and the largest such sum.	Medium6	SortingHash map+1	No attempts yet	5s	512 MB	Judgeable
Coin ExchangeGiven the generating-function coefficients of a coin multiset, answer queries that remove N coins of value V and report the new coefficient of x^D modulo 1e9+7.	Medium6	Dynamic programmingCombinatorics+1	No attempts yet	2s	512 MB	Judgeable
Iterated SumsCompute S(k, n) mod 1,000,000,007, where S iterates prefix sums k times starting from S(0, n) = n.	Medium6	CombinatoricsMath+1	No attempts yet	2s	512 MB	Judgeable
Circles tangent to a lineArrange N given circles on one side of a line, each touching it, without interiors overlapping, and minimize the span between the leftmost and rightmost touch points.	Medium6	Brute forceGeometry+1	No attempts yet	2s	512 MB	Judgeable
Magic TreesGiven a directed graph, repeatedly pick a vertex to mark magic and let magic or protected vertices protect their out-neighbors; maximize magic and unprotected vertices.	Medium6	GraphGreedy	No attempts yet	2s	512 MB	Judgeable
GoPlace black stones to capture dead white stones, where a white stone dies when all its empty neighbors are filled, and maximize the final count of empty cells.	Medium6	GraphGreedy+2	No attempts yet	2s	512 MB	Judgeable