Problems

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Total results21,641 problems

Knights and DragonsHard8
Geometry, Sorting +2No attempts yetTime limit4sMemory limit512 MB
Judgeable
Adding ParenthesesHard8
Dynamic programming, Recursion +2No attempts yetTime limit0.5sMemory limit512 MB
Judgeable
Add Parentheses 3Hard8
Divide and conquer, Dynamic programming +2No attempts yetTime limit1.5sMemory limit512 MB
Judgeable
Fraction ChallengeHard8
String, Hash map +2No attempts yetTime limit0.5sMemory limit512 MB
Judgeable
Counting StairsHard8
Dynamic programming, Math +2No attempts yetTime limit3sMemory limit512 MB
Judgeable
Distinct SubstringsHard8
String matching, Math +1No attempts yetTime limit3sMemory limit512 MB
Judgeable
Distance SumHard8
Graph, BFS +2No attempts yetTime limit4sMemory limit512 MB
Judgeable
FractionsHard8
Math, Number theory +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
King Kog's ReceptionHard8
Segment tree, Binary search +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
HikingHard8
Graph, Shortest path +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
Three Primary ColorsHard8
Divide and conquer, Segment tree +2No attempts yetTime limit3sMemory limit256 MB
Judgeable
XOR PokerHard8
Bit manipulation, Greedy +1No attempts yetTime limit2sMemory limit512 MB
Judgeable
The ABCD MurdererHard8
String matching, Array +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Shooter IslandHard8
Union-find, Intervals +2No attempts yetTime limit3sMemory limit512 MB
Judgeable
Erasing MatrixHard8
Graph, Greedy +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
Katty and WonkiHard8
Tree, Graph +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
The Pied PiperHard8
Graph, Simulation +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
Nader ShahHard8
Graph, Greedy +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Python ClassesHard8
Greedy, Union-find +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Shortest Common Non-SubsequenceHard8
Dynamic programming, Greedy +2No attempts yetTime limit5sMemory limit512 MB
Judgeable
What Goes Up Must Come DownHard8
Divide and conquer, Sorting +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Colorful TreeHard8
Tree, DFS +2No attempts yetTime limit5sMemory limit512 MB
Judgeable
Metal Bar CubeHard8
Greedy, Implementation +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Balance BeamHard8
Dynamic programming, Math +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Sort It OutHard8
Sorting, Combinatorics +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
BulldozerHard8
Geometry, Sorting +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
IlluminationHard8
Dynamic programming, Segment tree +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Trodden CableHard8
Shortest path, Graph +2No attempts yetTime limit5sMemory limit512 MB
Judgeable
Spotlight MovementHard8
Geometry, Simulation +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Gravity PointHard8
Geometry, Probability +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Identity FunctionHard8
Math, Number theory +1No attempts yetTime limit5sMemory limit512 MB
Judgeable
Live ProgrammingHard8
Dynamic programming, Sorting +2No attempts yetTime limit5sMemory limit512 MB
Judgeable
Endless BFSHard8
Graph, BFS +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Librarian's WorkHard8
Greedy, Dynamic programming +2No attempts yetTime limit5sMemory limit512 MB
Judgeable
Permutation PeriodHard8
Math, Number theory +2No attempts yetTime limit5sMemory limit512 MB
Judgeable
Santa's GiftHard8
Dynamic programming, Greedy +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Prefix Suffix SearchHard8
String matching, Trie +2No attempts yetTime limit3sMemory limit512 MB
Judgeable
Nim without ZeroHard8
Game theory, Bit manipulation +1No attempts yetTime limit2sMemory limit512 MB
Judgeable
Sum of QQHard8
Math, Number theory +1No attempts yetTime limit2sMemory limit512 MB
Judgeable
Clique ColoringHard8
Combinatorics, Math +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Cat DatingHard8
DFS, Greedy +2No attempts yetTime limit4sMemory limit1024 MB
Judgeable
DifferenceHard8
Simulation, Math +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Pear-wise VotingHard8
Bit manipulation, Dynamic programming +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Sequential YahtzeeHard8
Dynamic programming, Prefix sum +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Funny Number GameHard8
Bit manipulation, Math +2No attempts yetTime limit0.5sMemory limit512 MB
Judgeable
Fibonacci NimHard8
Game theory, Math +2No attempts yetTime limit0.5sMemory limit512 MB
Judgeable
Card GameHard8
Game theory, Dynamic programming +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Knight GameHard8
Game theory, Math +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Sum of VectorsHard8
Sorting, Geometry +2No attempts yetTime limit0.5sMemory limit512 MB
Judgeable
Naming the ComputerHard8
String matching, Dynamic programming +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
XOR MSTHard8
Trie, Minimum spanning tree +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Sequence and Queries 20Hard8
Trie, Bit manipulation +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Set and QueriesHard8
Bit manipulation, Math +2No attempts yetTime limit4sMemory limit512 MB
Judgeable
XOR SubmatrixHard8
Bit manipulation, Trie +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Distinct Substring Queries 2Hard8
String, String matching +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Graph and QueriesHard8
Graph, Union-find +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Tree and Queries 12Hard8
Tree, Union-find +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Substring ReplacementHard8
Dynamic programming, String matching +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
K-th SubstringHard8
String, Trie +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
String FoldingHard8
String, Brute force +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Chessboard Tour 1Hard8
BFS, Shortest path +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Number of Integer Lattice PointsHard8
Math, Number theory +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Sequence and Queries 22Hard8
Segment tree, Divide and conquer +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
MaaaaaaaaazeHard8
Brute force, BFS +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Maximum Subarray Sum and QueriesHard8
Segment tree, Divide and conquer +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Rope and QueriesHard8
Linked list, Implementation +2No attempts yetTime limit0.3sMemory limit512 MB
Judgeable
Piece of CakeHard8
Combinatorics, Geometry +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
It's a Mod, Mod, Mod, Mod WorldHard8
Math, Number theory +2No attempts yetTime limit5sMemory limit512 MB
Judgeable
Heaps of FunHard8
Probability, Dynamic programming +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Intersecting RectanglesHard8
Sorting, Segment tree +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Planes, Trains, but not AutomobilesHard8
Graph, Dynamic programming +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
3-SAT 2Hard8
Graph, DFS +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
RedistrictingHard8
Dynamic programming, Prefix sum +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
ShortcutHard8
Graph, Shortest path +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Cow DatingHard8
Math, Two pointers +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Cow LandHard8
Tree, DFS +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Painting the Barn (Gold)Hard8
Prefix sum, Matrix +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
KisikHard8
Sorting, Divide and conquer +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
SymphonyHard8
Sorting, Binary search +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Artifact RestorationHard8
Math, Number theory +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Broken DataHard8
Implementation, Greedy +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Ants on a CircleHard8
Math, Simulation +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
TouristHard8
Graph, Shortest path +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Truth TellersHard8
Array, Segment tree +2No attempts yetTime limit3.5sMemory limit256 MB
Judgeable
Candy BoxesHard8
Dynamic programming, Greedy +1No attempts yetTime limit1.5sMemory limit512 MB
Judgeable
Dynamic CentroidHard8
Tree, DFS +2No attempts yetTime limit1.5sMemory limit512 MB
Judgeable
Raider Choragi and Queries (Normal)Hard8
Dynamic programming, Segment tree +2No attempts yetTime limit5sMemory limit512 MB
Judgeable
SEGWAYHard8
Simulation, Implementation +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Circular DNAHard8
Array, Stack +2No attempts yetTime limit3sMemory limit512 MB
Judgeable
GosuHard8
Graph, BFS +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Alpine ValleyHard8
Tree, Graph +2No attempts yetTime limit3sMemory limit512 MB
Judgeable
Whiskey TradeHard8
Graph, Shortest path +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
String DecorationHard8
String, Sliding window +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Overflowing PopularityHard8
Dynamic programming, Greedy +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
The Valley OverflowsHard8
Tree, DFS +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Card Factory (Large)Hard8
Sorting, Binary search +2No attempts yetTime limit3sMemory limit256 MB
Judgeable
NC StringHard8
Combinatorics, Dynamic programming +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Making Everything WhiteHard8
Greedy, Implementation +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Superb DartHard8
Geometry, Graph +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Enchanted ForestHard8
Graph, Divide and conquer +2No attempts yetTime limit3sMemory limit512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Knights and DragonsGiven n distinct points (strength, magic), decide for each whether it lies in the convex hull of the others, since a point is reachable by repeated weighted averaging of the other points exactly when it is not a vertex of the hull.	Hard8	GeometrySorting+2	No attempts yet	4s	512 MB	Judgeable
Adding ParenthesesParenthesize a single-digit expression with non-nested single-operator parentheses to maximize its left-to-right value.	Hard8	Dynamic programmingRecursion+2	No attempts yet	0.5s	512 MB	Judgeable
Add Parentheses 3Parenthesize an alternating digit and +,-,* expression of length up to 19 to maximize its value, respecting left-to-right and multiplication-first rules.	Hard8	Divide and conquerDynamic programming+2	No attempts yet	1.5s	512 MB	Judgeable
Fraction ChallengeMultiply many huge fractions given as digit strings and output the reduced product as a/b.	Hard8	StringHash map+2	No attempts yet	0.5s	512 MB	Judgeable
Counting StairsCount symmetric stairs (partitions of n into distinct parts) with n cubes, modulo 998244353, for up to 1e4 queries with n up to 2e5.	Hard8	Dynamic programmingMath+2	No attempts yet	3s	512 MB	Judgeable
Distinct SubstringsGiven a period string p and length n, count distinct substrings of the string formed by repeating p and cutting to n. n may be 1e9.	Hard8	String matchingMath+1	No attempts yet	3s	512 MB	Judgeable
Distance SumGiven a connected undirected unweighted graph with at most n+42 edges, compute the sum of shortest-path distances over all unordered vertex pairs.	Hard8	GraphBFS+2	No attempts yet	4s	512 MB	Judgeable
FractionsGiven n, represent 1 - 1/n as a sum of fractions with denominators dividing n and strictly between 1 and n, or report that no such sum exists.	Hard8	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
King Kog's ReceptionKnights join or cancel reservations with a start time and duration; after each change, a query asks how long a visitor arriving at time t must wait, since she yields to a knight arriving at the same instant.	Hard8	Segment treeBinary search+2	No attempts yet	2s	512 MB	Judgeable
HikingPick a non-end point as the goal, walk uphill from node 1 to it and downhill to node N, and maximize h*E minus D times total distance or report that no route exists.	Hard8	GraphShortest path+2	No attempts yet	1s	256 MB	Judgeable
Three Primary ColorsGiven up to 25,000 colored rectangles painted one at a time without repainting already covered pixels, report the total area of each of the seven resulting color regions.	Hard8	Divide and conquerSegment tree+2	No attempts yet	3s	256 MB	Judgeable
XOR PokerGiven N integers, choose a nonempty subset of even size whose XOR is maximum and print that value.	Hard8	Bit manipulationGreedy+1	No attempts yet	2s	512 MB	Judgeable
The ABCD MurdererFind the fewest word occurrences needed to cover a target text exactly when cut-outs may overlap on matching text, or report -1 if impossible.	Hard8	String matchingArray+2	No attempts yet	2s	512 MB	Judgeable
Shooter IslandOn a 50 by 100000 grid, rectangles flood when hit, and after each query decide whether a radius-0.31416 boat can sail between two given squares on the remaining water.	Hard8	Union-findIntervals+2	No attempts yet	3s	512 MB	Judgeable
Erasing MatrixDecide whether all cells of a grid can be driven to zero by repeatedly adding the same integer k to two adjacent cells while keeping every value non-negative, and print a valid sequence of at most 10^6 operations.	Hard8	GraphGreedy+2	No attempts yet	1s	256 MB	Judgeable
Katty and WonkiAdd 2 edges to an N-vertex tree to maximize vertices lying on created cycles; return that maximum for the worst case for the tree owner.	Hard8	TreeGraph+2	No attempts yet	1s	256 MB	Judgeable
The Pied PiperPlace the fewest cells so every frozen walk under the U/D/L/R map enters a safe cell; model directed functional reverse graphs and find a minimum set of path-starting states.	Hard8	GraphSimulation+2	No attempts yet	1s	256 MB	Judgeable
Nader ShahFrom roads and marked Afshari edges, reconstruct the root and capture order consistent with the growth rule, lexicographically minimum, or output Wrong Map!.	Hard8	GraphGreedy+2	No attempts yet	2s	512 MB	Judgeable
Python ClassesReorder single-inheritance class definitions so every superclass appears before its subclasses, using the fewest cut-and-paste moves, or output -1 when superclass links form a cycle.	Hard8	GreedyUnion-find+2	No attempts yet	2s	512 MB	Judgeable
Shortest Common Non-SubsequenceGiven two binary strings of length up to 4000, find the shortest binary string that is a subsequence of neither, breaking ties by lexicographic order.	Hard8	Dynamic programmingGreedy+2	No attempts yet	5s	512 MB	Judgeable
What Goes Up Must Come DownRearrange the cards by adjacent swaps into a bitonic order with the fewest moves, counting inversions by value.	Hard8	Divide and conquerSorting+2	No attempts yet	2s	512 MB	Judgeable
Colorful TreeMaintain vertex colors on a tree under point updates and answer queries giving the number of edges in the minimal subtree spanning all vertices of one color.	Hard8	TreeDFS+2	No attempts yet	5s	512 MB	Judgeable
Metal Bar CubeGiven the four viewing counts from left, right, top and bottom of an N by N grid, decide whether any placement of blocked cells can produce exactly those counts.	Hard8	GreedyImplementation+2	No attempts yet	1s	512 MB	Judgeable
Balance BeamChoose at each beam position a cash value or a fair coin random walk stopped at the ends, maximizing expected payment for every starting position.	Hard8	Dynamic programmingMath+2	No attempts yet	2s	512 MB	Judgeable
Sort It OutFind the smallest subset of cow IDs S such that repeatedly yelling at each ID in S in increasing order eventually sorts the permutation, then output the K-th lexicographically smallest such subset.	Hard8	SortingCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
BulldozerChoose two parallel lines and take every weighted point between them, maximizing the sum of gold values minus rock costs.	Hard8	GeometrySorting+2	No attempts yet	2s	512 MB	Judgeable
IlluminationChoose a subset of trees to decorate, maximizing total beauty, so that for each of M given intervals at most one tree inside it is chosen.	Hard8	Dynamic programmingSegment tree+2	No attempts yet	2s	512 MB	Judgeable
Trodden CablePlace a cable along grid edges connecting two given corners so that, over repeated fixed walks, staff cross it as few times as possible.	Hard8	Shortest pathGraph+2	No attempts yet	5s	512 MB	Judgeable
Spotlight MovementGiven N spotlights whose centers move around polygonal orbits, decide whether Ciel can walk from a start point to an end point while staying inside at least one illuminated circle at all times.	Hard8	GeometrySimulation+2	No attempts yet	2s	512 MB	Judgeable
Gravity PointA random mass for tiles A and B is drawn from given ranges; find the chance the grid's center of gravity falls in a filled cell.	Hard8	GeometryProbability+2	No attempts yet	2s	512 MB	Judgeable
Identity FunctionGiven N, find the smallest positive k with every iterate F_k(a)=a for 1<=a<N under f(a)=a^N mod N, or output -1.	Hard8	MathNumber theory+1	No attempts yet	5s	512 MB	Judgeable
Live ProgrammingChoose a subset of songs within total length T and order them to maximize the sum of basic points minus squared feature differences between consecutive songs.	Hard8	Dynamic programmingSorting+2	No attempts yet	5s	512 MB	Judgeable
Endless BFSRun a BFS that forgets visited vertices, so the active set alternates between bipartition classes. Decide whether it ever equals all vertices and report the least step when it does.	Hard8	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
Librarian's WorkGiven a shuffled permutation with book weights, restore the original order using two adjacent-rotation-like moves and minimize total labor cost.	Hard8	GreedyDynamic programming+2	No attempts yet	5s	512 MB	Judgeable
Permutation PeriodStarting from the identity permutation, apply swaps one at a time and after each swap report the permutation's period modulo 1e9+7, where the period is the LCM of its cycle lengths.	Hard8	MathNumber theory+2	No attempts yet	5s	512 MB	Judgeable
Santa's GiftFor each family size k from 1 to M, choose a subset of gift kinds so k copies of each fit in capacity C, maximizing total price.	Hard8	Dynamic programmingGreedy+2	No attempts yet	2s	512 MB	Judgeable
Prefix Suffix SearchGiven N words and Q prefix/suffix pairs, report for each query how many words match both prefix and suffix. Total input length is up to 2.5 million.	Hard8	String matchingTrie+2	No attempts yet	3s	512 MB	Judgeable
Nim without ZeroAn impartial game where a move loses if it makes the XOR of all heap sizes equal zero. Decide the winner with optimal play.	Hard8	Game theoryBit manipulation+1	No attempts yet	2s	512 MB	Judgeable
Sum of QQCount axis-parallel rectangles in the multiplication table whose entries sum to exactly S, with S up to 100000.	Hard8	MathNumber theory+1	No attempts yet	2s	512 MB	Judgeable
Clique ColoringGiven up to five clique sizes, find the smallest number of vertices in a complete graph whose edges can be covered by cliques of those sizes with no repeated edge.	Hard8	CombinatoricsMath+2	No attempts yet	2s	512 MB	Judgeable
Cat DatingIn a rooted tree, each den holds female cats or male cats with a fall limit; count the maximum number of female-male pairs where a male can reach a female downward within the distance limit.	Hard8	DFSGreedy+2	No attempts yet	4s	1024 MB	Judgeable
DifferenceBuild the sequence from A1 incrementally, adding each next gap so that m hits as a value or an existing difference; report the first step that covers it.	Hard8	SimulationMath+2	No attempts yet	2s	512 MB	Judgeable
Pear-wise VotingGiven ranked ballots and a selectable candidate order, decide for each candidate whether some agenda makes that candidate win sequential pairwise contests.	Hard8	Bit manipulationDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Sequential YahtzeeGiven up to 195 sequential dice rolls, assign consecutive segments to the 13 Yahtzee categories in order to maximize the total score.	Hard8	Dynamic programmingPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
Funny Number GameGiven a 4-digit N and M turns of incrementing one digit with 9 wrapping to 0, decide which player forces the final value above N.	Hard8	Bit manipulationMath+2	No attempts yet	0.5s	512 MB	Judgeable
Fibonacci NimFind which piles lose the Fibonacci-Nim take-away game and decide the winner of the multi-pile sum game with optimal play.	Hard8	Game theoryMath+2	No attempts yet	0.5s	512 MB	Judgeable
Card GameTwo players alternately remove a chosen card and every card with a smaller number; decide the winner under optimal play.	Hard8	Game theoryDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Knight GameTwo players alternately place non-attacking knights on an N x N board; decide who wins under optimal play, with N up to 10,000.	Hard8	Game theoryMath+2	No attempts yet	1s	512 MB	Judgeable
Sum of VectorsChoose two of N vectors, each optionally sign-flipped per coordinate, to minimize the norm of their sum and output the pair with the chosen flips.	Hard8	SortingGeometry+2	No attempts yet	0.5s	512 MB	Judgeable
Naming the ComputerGiven a string S and integer K, find the shortest string that contains S as a substring at least K times, and output its length.	Hard8	String matchingDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
XOR MSTGiven N labeled vertices where the edge between any two has weight equal to the XOR of their labels, find the total cost of the minimum spanning tree.	Hard8	TrieMinimum spanning tree+2	No attempts yet	2s	512 MB	Judgeable
Sequence and Queries 20Maintain a multiset that starts with only 0, supporting insert, delete, and max-XOR queries where every element is XORed with x.	Hard8	TrieBit manipulation+2	No attempts yet	1s	512 MB	Judgeable
Set and QueriesAfter each insertion or deletion in a set of up to 500,000 integers, report the maximum XOR achievable by any subset of the current set.	Hard8	Bit manipulationMath+2	No attempts yet	4s	512 MB	Judgeable
XOR SubmatrixBuild the N by M matrix with A[i][j] = V[i] xor U[j] and find the submatrix whose elementwise xor is maximal.	Hard8	Bit manipulationTrie+2	No attempts yet	2s	512 MB	Judgeable
Distinct Substring Queries 2Process a stream of append-character and count-distinct-substrings queries on a growing string, answering each count query online.	Hard8	StringString matching+2	No attempts yet	1s	512 MB	Judgeable
Graph and QueriesMaintain an undirected graph under edge insertions and deletions, answering connectivity queries between two vertices after each update.	Hard8	GraphUnion-find+2	No attempts yet	2s	512 MB	Judgeable
Tree and Queries 12Maintain a forest under edge insertions and deletions, and answer connectivity queries between two vertices.	Hard8	TreeUnion-find+2	No attempts yet	2s	512 MB	Judgeable
Substring ReplacementReplace each question mark in S with a lowercase letter so that T appears as a substring as many times as possible, and report that maximum count.	Hard8	Dynamic programmingString matching+2	No attempts yet	2s	512 MB	Judgeable
K-th SubstringGiven a string S, answer queries that ask for the K-th distinct substring of S in lexicographic order, or -1 if it does not exist.	Hard8	StringTrie+2	No attempts yet	2s	512 MB	Judgeable
String FoldingFold the string at a sequence of positions into vertical columns, then find the longest column-run of one repeated character that starts at the bottom with no gaps.	Hard8	StringBrute force+2	No attempts yet	2s	512 MB	Judgeable
Chessboard Tour 1On an N by N board holding distinct numbers, find the fewest seconds (each a single piece move or a piece swap) to travel through squares 1, 2, ..., N^2 in order using a knight, bishop, and rook.	Hard8	BFSShortest path+2	No attempts yet	2s	512 MB	Judgeable
Number of Integer Lattice PointsCount pairs of lattice points in a grid whose connecting segment contains exactly K lattice points.	Hard8	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Sequence and Queries 22Given a sequence and a stream of updates and range-sum queries, answer each query for the sequence state after its k-th update only, where k can be any earlier prefix of updates.	Hard8	Segment treeDivide and conquer+2	No attempts yet	1s	512 MB	Judgeable
MaaaaaaaaazeGiven five 5x5 boards, rotate each freely, stack them in any order, then find the shortest path through the resulting 5x5x5 cube from one corner to the opposite corner.	Hard8	Brute forceBFS+2	No attempts yet	2s	512 MB	Judgeable
Maximum Subarray Sum and QueriesGiven an array, answer queries that ask for the maximum subarray sum inside a given index range.	Hard8	Segment treeDivide and conquer+2	No attempts yet	2s	512 MB	Judgeable
Rope and QueriesMaintain a string under up to 100,000 queries that cut a substring and move it to the front or back, and print single characters.	Hard8	Linked listImplementation+2	No attempts yet	0.3s	512 MB	Judgeable
Piece of CakeGiven a convex polygon with n vertices in clockwise order, compute the expected area of the convex polygon formed by picking k of the vertices uniformly at random.	Hard8	CombinatoricsGeometry+2	No attempts yet	2s	512 MB	Judgeable
It's a Mod, Mod, Mod, Mod WorldGiven p, q, n, compute the sum of (p*i mod q) for i from 1 to n, for up to 100000 queries with values up to 10^6.	Hard8	MathNumber theory+2	No attempts yet	5s	512 MB	Judgeable
Heaps of FunGiven a rooted tree where each node i draws a uniform random real in [0, b_i], compute the probability that every parent's value is less than both its children's values, modulo 1e9+7.	Hard8	ProbabilityDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Intersecting RectanglesGiven n axis-aligned rectangles with all x and y coordinates distinct, decide whether any two boundaries cross or touch. One rectangle fully containing another does not count.	Hard8	SortingSegment tree+2	No attempts yet	2s	512 MB	Judgeable
Planes, Trains, but not AutomobilesGiven a DAG of one-way train lines and complete flight connectivity, find the minimum number of flights to visit every city once and list all cities whose airport can be used on some optimal route.	Hard8	GraphDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
3-SAT 2Given a 3-CNF formula with N variables and M clauses, decide whether it is satisfiable and, if so, output a satisfying assignment.	Hard8	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
RedistrictingGiven a string of H and G representing a line of cows, split it into contiguous districts of length at most K minimizing the number of districts where G outnumbers or ties H.	Hard8	Dynamic programmingPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
ShortcutGiven a weighted undirected graph with cows at each node, add one shortcut edge from node 1 to any other node to maximize the total decrease in shortest-path travel time.	Hard8	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
Cow DatingGiven probabilities p_i, choose a contiguous interval maximizing the chance that exactly one bull accepts, and print 10^6 times that probability rounded down.	Hard8	MathTwo pointers+2	No attempts yet	2s	512 MB	Judgeable
Cow LandOn a weighted tree, support point value updates and path XOR queries between any two nodes, returning the XOR of enjoyment values along the unique route.	Hard8	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
Painting the Barn (Gold)Given N painted axis-aligned rectangles on a 200x200 grid, add up to two disjoint rectangles to maximize the total area covered by exactly K coats.	Hard8	Prefix sumMatrix+2	No attempts yet	2s	512 MB	Judgeable
KisikChoose K of N distinct buildings, arrange them side by side on the ground, and minimize the area of the enclosing bounding rectangle.	Hard8	SortingDivide and conquer+2	No attempts yet	2s	512 MB	Judgeable
SymphonyAdd one integer X to every element of A, then change at most K elements to any values, minimizing the sum of absolute differences against B.	Hard8	SortingBinary search+2	No attempts yet	1s	512 MB	Judgeable
Artifact RestorationGiven a grid with some unknown cells, fill unknowns with 0 or 1 so that the total number of people summed over all subrectangles is divisible by K.	Hard8	MathNumber theory+2	No attempts yet	1s	512 MB	Judgeable
Broken DataDelete some integers from a sequence so the rest reads as N M U1 V1 ... UM VM with 1 <= Ui,Vi <= N; among all valid restorations, maximize N, then M.	Hard8	ImplementationGreedy+2	No attempts yet	1s	512 MB	Judgeable
Ants on a CircleAnts move on a circle of N points, reversing on collision; for each query (P, X) find the earliest time point P has been visited at least X times.	Hard8	MathSimulation+2	No attempts yet	1s	512 MB	Judgeable
TouristGiven a weighted graph, for each city 2 through N find a shortest path from city 1, and count the minimum number of edges whose weights are re-photographed across all chosen paths.	Hard8	GraphShortest path+2	No attempts yet	1s	512 MB	Judgeable
Truth TellersGiven N people each stating a range for the number of truth tellers, find the maximum consistent truth-teller count after each of Q point updates.	Hard8	ArraySegment tree+2	No attempts yet	3.5s	256 MB	Judgeable
Candy BoxesGiven N boxes, each with m candies of sweetness a at cost c, find for every k from 1 to L the minimum price of boxes so that a subset of candies sums exactly to k.	Hard8	Dynamic programmingGreedy+1	No attempts yet	1.5s	512 MB	Judgeable
Dynamic CentroidFor each prefix tree formed by vertices 1..k, output the smallest centroid (the vertex whose removal leaves components of size at most k/2).	Hard8	TreeDFS+2	No attempts yet	1.5s	512 MB	Judgeable
Raider Choragi and Queries (Normal)A donut-shaped ring of 2N zones holds prisoner counts that change over Q updates; after each change, print the minimum number of squads, each covering one zone or two adjacent zones with total at most W.	Hard8	Dynamic programmingSegment tree+2	No attempts yet	5s	512 MB	Judgeable
SEGWAYSimulate N riders over a 300 m track with three speed sections and accelerators granting 1 s/m boost for X mod 20 meters, where X counts riders strictly ahead, and print each finish time.	Hard8	SimulationImplementation+2	No attempts yet	1s	512 MB	Judgeable
Circular DNAGiven a circular sequence of start and end markers for many gene types, choose a cut position that maximizes how many gene types have their markers properly nested in the resulting linear subsequence.	Hard8	ArrayStack+2	No attempts yet	3s	512 MB	Judgeable
GosuGiven a tournament where each pair has a winner, find a vertex whose maximum shortest directed distance to every other vertex is as small as possible.	Hard8	GraphBFS+2	No attempts yet	1s	1024 MB	Judgeable
Alpine ValleyGiven a weighted tree with shops and an exit, answer queries where one edge is removed and you need either the shortest distance to the exit or to the nearest shop from a village.	Hard8	TreeGraph+2	No attempts yet	3s	512 MB	Judgeable
Whiskey TradeModel the distribution network as a flow graph with node capacities and compute the maximum flow from Myeongjin to Jueun.	Hard8	GraphShortest path+2	No attempts yet	1s	256 MB	Judgeable
String DecorationGiven a string S and N pattern strings, find the length of the shortest substring of S that contains every pattern as a substring.	Hard8	StringSliding window+2	No attempts yet	2s	512 MB	Judgeable
Overflowing PopularityGiven M guests with arrival and departure times, choose when to insert up to K extra friends so that the count of ordinary attendees stays below T as long as possible.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	256 MB	Judgeable
The Valley OverflowsGiven a tree of valleys with heights, decide whether water starting from any non-K valley can reach valley K under the splash-up movement rule.	Hard8	TreeDFS+2	No attempts yet	1s	512 MB	Judgeable
Card Factory (Large)Each of N cards shows its front initially; given M queries K that flip every card whose visible number is at most K, report the final visible sum.	Hard8	SortingBinary search+2	No attempts yet	3s	256 MB	Judgeable
NC StringCount the permutations of chosen words (spaced apart) that contain an N before a later C, modulo 1e9+7.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Making Everything WhiteGiven an N by M black/white grid, choose for each cell one of three local color-inversion actions so that every cell ends up white, or report impossibility.	Hard8	GreedyImplementation+2	No attempts yet	1s	512 MB	Judgeable
Superb DartGiven a planar straight-line graph, list the areas of its bounded faces in increasing order, rounded to two decimals.	Hard8	GeometryGraph+2	No attempts yet	1s	512 MB	Judgeable
Enchanted ForestChoose a path from node 1 to node n minimizing the sum of the maximum a-value and maximum b-value over its edges.	Hard8	GraphDivide and conquer+2	No attempts yet	3s	512 MB	Judgeable