Problems

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Total results21,518 problems

Lonely Dreamoon 2Hard8
Sorting, Greedy +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Rectangles Inside RectangleHard8
Dynamic programming, Sorting +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
La Vie En RoseHard8
String matching, Dynamic programming +2No attempts yetTime limit2.5sMemory limit64 MB
Judgeable
Izhevsk Training CampHard8
Bit manipulation, Brute force +2No attempts yetTime limit3sMemory limit256 MB
Judgeable
Expected LCPHard8
Probability, Combinatorics +2No attempts yetTime limit1.5sMemory limit256 MB
Judgeable
ImmigrationHard8
Geometry, Math +2No attempts yetTime limit2sMemory limit256 MB
Judgeable
Graph Coloring 2Hard8
Dynamic programming, Bit manipulation +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
PhysicsHard8
Math, Sorting +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Array and OperationsHard8
Segment tree, Binary search +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Value of the ArrayHard8
Combinatorics, Sorting +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
VierHard8
Hash map, Math +2No attempts yetTime limit2sMemory limit256 MB
Judgeable
WeltallHard8
Combinatorics, Dynamic programming +2No attempts yetTime limit4sMemory limit256 MB
Judgeable
ChampionshipsHard8
Graph, Greedy +2No attempts yetTime limit1.5sMemory limit256 MB
Judgeable
TrianglesHard8
Geometry, Hash map +2No attempts yetTime limit10sMemory limit256 MB
Judgeable
Subtract if Greater!Hard8
Segment tree, Binary search +2No attempts yetTime limit5sMemory limit512 MB
Judgeable
Best DivisionHard8
Dynamic programming, Prefix sum +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
Intersection is Not Allowed!Hard8
Dynamic programming, Combinatorics +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
K-valueHard8
Binary search, Tree +2No attempts yetTime limit6sMemory limit256 MB
Judgeable
Eel and GridHard8
Combinatorics, Math +1No attempts yetTime limit1sMemory limit256 MB
Judgeable
Cups and BeansHard8
Game theory, Dynamic programming +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
Delivering FlyersHard8
Tree, Greedy +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Function ReconstructionHard8
Graph, Combinatorics +2No attempts yetTime limit1.5sMemory limit1024 MB
Judgeable
TriangulationHard8
Combinatorics, Dynamic programming +2No attempts yetTime limit2.5sMemory limit256 MB
Judgeable
Drought (Large)Hard8
Dynamic programming, Greedy +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Taking ItemsHard8
Graph, Dynamic programming +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Second Diameter of a TreeHard8
Tree, DFS +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Urban BlightHard8
Geometry, Sorting +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Voucher PreparationHard8
Greedy, Sorting +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Searching for StringsHard8
Sliding window, String matching +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Swapping SeatsHard8
Greedy, Sliding window +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
A Game with GrundyHard8
Geometry, Sorting +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Exercise DeadlinesHard8
Greedy, Sorting +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Flop SortingHard8
Implementation, Sorting +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
How Many Burgers?Hard8
Dynamic programming, Greedy +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
FeastHard8
Dynamic programming, Greedy +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Internet ProblemHard8
Graph, DFS +2No attempts yetTime limit5sMemory limit512 MB
Judgeable
Fancy FenceHard8
Stack, Divide and conquer +2No attempts yetTime limit1sMemory limit32 MB
Judgeable
ExperimentHard8
Graph, Simulation +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Roadside AdvertisementsHard8
Tree, Graph +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Rock ClimbingHard8
Graph, Greedy +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Panda SkiHard8
Graph, Dynamic programming +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Cash GapHard8
Greedy, Sorting +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Jet TrainsHard8
Union-find, Graph +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Flexible SegmentsHard8
Number theory, Math +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Counting in the OrderHard8
Stack, Array +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Right-hand obstructionHard8
Simulation, Queue +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Operation <<Permutation>>Hard8
Graph, Topological sort +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Shushpanchiks and the CinemaHard8
Math, Intervals +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Cipher BreakingHard8
Graph, DFS +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
A Strange ExhibitHard8
Implementation, Greedy +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
String ProcessingHard8
Divide and conquer, String +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Planet NineHard8
Math, Number theory +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Similar ArraysHard8
Graph, DFS +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
LinearizationHard8
Bit manipulation, Prefix sum +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Equal MaximumsHard8
Array, Stack +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Pandemic 2Hard8
Tree, DFS +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Heavy BurgerHard8
Segment tree, String matching +2No attempts yetTime limit3sMemory limit1024 MB
Judgeable
BusHard8
Simulation, Greedy +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
«Exclusive or» Strikes BackHard8
Bit manipulation, Number theory +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
SpeedingHard8
Binary search, Greedy +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
PostersHard8
Dynamic programming, Segment tree +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
QuadtreeHard8
Tree, Dynamic programming +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
GarlandHard8
Dynamic programming, String +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Broken Line 04Hard8
Sorting, Greedy +2No attempts yetTime limit0.1sMemory limit512 MB
Judgeable
Broken Line 05Hard8
Greedy, Sorting +2No attempts yetTime limit0.1sMemory limit512 MB
Judgeable
Broken Line 08Hard8
Sorting, Greedy +2No attempts yetTime limit0.1sMemory limit512 MB
Judgeable
Handcrafted GiftHard8
Greedy, Sorting +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Painting SquaresHard8
String, Combinatorics +2No attempts yetTime limit4sMemory limit1024 MB
Judgeable
Carnival TicketsHard8
Greedy, Sorting +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Counting MushroomsHard8
Implementation, Math +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
StationsHard8
Tree, DFS +2No attempts yetTime limit20sMemory limit1024 MB
Judgeable
Sea BattleHard8
Math, Number theory +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Turtles in the PondHard8
Graph, Union-find +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Painting the FenceHard8
Greedy, Binary search +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Rotating PlateHard8
Geometry, Binary search +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Strange CityHard8
Graph, DFS +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Min-hashingHard8
Graph, Simulation +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Remote ControlHard8
Simulation, Prefix sum +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Bit StringHard8
Dynamic programming, String matching +2No attempts yetTime limit1.5sMemory limit1024 MB
Judgeable
Trading SystemHard8
Heap, Prefix sum +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Counting the Number of TreesHard8
Dynamic programming, Tree +2No attempts yetTime limit2sMemory limit256 MB
Judgeable
Nowruz 2Hard8
Graph, Tree +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Nowruz 3Hard8
Graph, Tree +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Nowruz 9Hard8
Graph, Tree +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Nowruz 10Hard8
Graph, Tree +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Toy TrainHard8
Graph, Game theory +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Cup of JamshidHard8
Bit manipulation, Binary search +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Last SupperHard8
Greedy, Implementation +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Card ShuffleHard8
Implementation, Math +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
Vista 1Hard8
Geometry, Greedy +2No attempts yetTime limit0.1sMemory limit128 MB
Judgeable
Vista 2Hard8
Geometry, Greedy +2No attempts yetTime limit0.1sMemory limit128 MB
Judgeable
Hero Loves Powers of Two! Hero Loves Powers of Two!Hard8
Bit manipulation, Greedy +2No attempts yetTime limit2.2sMemory limit222 MB
Judgeable
Since It Has Come to This, Become the Memorization KingHard8
Tree, DFS +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Dessert CaféHard8
Tree, Graph +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Imprecise ComputerHard8
Greedy, Math +1No attempts yetTime limit1sMemory limit512 MB
Judgeable
SwitchesHard8
Math, Matrix +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Bubble BubbleHard8
Sorting, Prefix sum +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Trees Hate Queries~Hard8
Segment tree, Prefix sum +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Icpcan AlphabetHard8
Dynamic programming, Brute force +2No attempts yetTime limit3sMemory limit512 MB
Judgeable
Nunchucks ShopHard8
Combinatorics, Math +2No attempts yetTime limit2sMemory limit512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Lonely Dreamoon 2Reorder the given integers so that the smallest absolute difference between adjacent elements is as large as possible, and print any optimal ordering.	Hard8	SortingGreedy+2	No attempts yet	1s	512 MB	Judgeable
Rectangles Inside RectanglePick a non-overlapping subset of axis-parallel rectangles that each touch the left or right side of a big rectangle, maximizing total weight.	Hard8	Dynamic programmingSorting+2	No attempts yet	1s	512 MB	Judgeable
La Vie En RoseCount which length-m windows of s can be produced from pattern p by swapping disjoint adjacent pairs that are non-overlapping and strictly separated.	Hard8	String matchingDynamic programming+2	No attempts yet	2.5s	64 MB	Judgeable
Izhevsk Training CampGiven nine contests, each a ranking of n teams, pick three contests so that the number of team pairs ordered the same way in all three is minimized.	Hard8	Bit manipulationBrute force+2	No attempts yet	3s	256 MB	Judgeable
Expected LCPCompute the expected length of the longest common prefix among n independent uniform random infinite binary strings, output as a fraction mod 1e9+7.	Hard8	ProbabilityCombinatorics+2	No attempts yet	1.5s	256 MB	Judgeable
ImmigrationPeter moves along the x-axis while tracking an object whose velocity changes n times; find the maximum absolute angular speed of his gaze from time t0 onward.	Hard8	GeometryMath+2	No attempts yet	2s	256 MB	Judgeable
Graph Coloring 2Compute the chromatic number of every non-empty vertex subset of a graph with n at most 18, then fold the values into one hash.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
PhysicsBalls move on a line with acceleration tied to speed, collide elastically, and each query asks for the k-th smallest velocity at time t.	Hard8	MathSorting+2	No attempts yet	1s	512 MB	Judgeable
Array and OperationsMaintain an array under range add, range floor-square-root, and range sum queries, printing each sum.	Hard8	Segment treeBinary search+2	No attempts yet	1s	512 MB	Judgeable
Value of the ArrayFor each k from 1 to n, sum over all non-empty subsequences the sum of their min(size, k) largest elements, modulo 998244353.	Hard8	CombinatoricsSorting+2	No attempts yet	1s	512 MB	Judgeable
VierGiven a random permutation, find two distinct unordered pairs with equal sums of indices and equal sums of permutation values, both modulo n.	Hard8	Hash mapMath+2	No attempts yet	2s	256 MB	Judgeable
WeltallFind the d-th lexicographic permutation of 1..n that has exactly k fixed points.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	4s	256 MB	Judgeable
ChampionshipsFind the largest set S of vertices such that the induced subgraph on S is connected and every vertex in S has degree at least d within S.	Hard8	GraphGreedy+2	No attempts yet	1.5s	256 MB	Judgeable
TrianglesGiven up to 2000 distinct points, count right triangles formed by three of the points whose area falls in the inclusive range [A, B].	Hard8	GeometryHash map+2	No attempts yet	10s	256 MB	Judgeable
Subtract if Greater!Maintain a multiset under queries that ask for the k-th smallest element and queries that subtract x from every element greater than x, then report each k-th smallest.	Hard8	Segment treeBinary search+2	No attempts yet	5s	512 MB	Judgeable
Best DivisionGiven a pseudorandom array, find the largest K such that A can be split into K nonempty intervals of length at most L, each with XOR sum at most X.	Hard8	Dynamic programmingPrefix sum+2	No attempts yet	1s	256 MB	Judgeable
Intersection is Not Allowed!Count the ways to route K non-crossing monotone paths from fixed top squares to fixed bottom squares on an N by N board, modulo 1e9+7.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	1s	256 MB	Judgeable
K-valueGiven a weighted tree, find the minimum k-value among simple paths with between L and R edges, where the k-value is the element at rank floor(r/k)+1 of the sorted edge weights.	Hard8	Binary searchTree+2	No attempts yet	6s	256 MB	Judgeable
Eel and GridAn eel on a toroidal H by W grid walks right or down, painting cells, until it returns to a painted cell; count Hamiltonian-style walks that cover every cell and end at (0,0).	Hard8	CombinatoricsMath+1	No attempts yet	1s	256 MB	Judgeable
Cups and BeansBeans sit in cups 1 through N-1, each with a move limit C_i; players alternate sliding one bean to a lower cup and whoever cannot move loses. Decide the winner.	Hard8	Game theoryDynamic programming+2	No attempts yet	1s	256 MB	Judgeable
Delivering FlyersOn a unit-weight tree, find the shortest closed walk from S that covers every node, given the rider can cover all nodes within distance D from any single stop.	Hard8	TreeGreedy+2	No attempts yet	1s	1024 MB	Judgeable
Function ReconstructionGiven the full reachability matrix of a functional graph on N nodes, count the number of functions f consistent with it, modulo 1e9+7.	Hard8	GraphCombinatorics+2	No attempts yet	1.5s	1024 MB	Judgeable
TriangulationCount, over all triangulations of a regular N-gon with a proper red/blue coloring, the total number of red triangles, modulo 998244353.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	2.5s	256 MB	Judgeable
Drought (Large)Maximize the sum of a_i minus the sum of b_j over nonnegative reals a and b subject to a_i - b_j <= c_ij, then round the answer to the nearest integer.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	1024 MB	Judgeable
Taking ItemsEach item may require others first, cycles mean all-or-nothing; pick a feasible set of items maximizing total mood change.	Hard8	GraphDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
Second Diameter of a TreeGiven a weighted tree with up to 100,000 vertices, find the distance of the second farthest pair of vertices, allowing a tie with the diameter.	Hard8	TreeDFS+2	No attempts yet	1s	1024 MB	Judgeable
Urban BlightGiven points and weighted segments, find a horizontal line whose intersection with the segments maximizes the total weight of segments it touches.	Hard8	GeometrySorting+2	No attempts yet	2s	1024 MB	Judgeable
Voucher PreparationGiven members with distinct skills and names, answer many queries: remove the b highest-skilled members, then partition the best M*a remaining into a teams to maximize the summed product of skills, and output the XOR of the names of all chosen members.	Hard8	GreedySorting+2	No attempts yet	2s	1024 MB	Judgeable
Searching for StringsCount how many distinct permutations of the needle string N occur as a contiguous substring of the haystack string H.	Hard8	Sliding windowString matching+2	No attempts yet	2s	512 MB	Judgeable
Swapping SeatsGiven a circular string of A, B, C, find the minimum number of seat swaps needed so each letter forms one contiguous block.	Hard8	GreedySliding window+2	No attempts yet	2s	512 MB	Judgeable
A Game with GrundyFor each i from 0 to N, count integer x positions with L <= x <= R that lie strictly inside at most i of N triangular visibility wedges.	Hard8	GeometrySorting+2	No attempts yet	1s	512 MB	Judgeable
Exercise DeadlinesEach of N unit-time exercises has a deadline; find the minimum number of adjacent swaps of the identity permutation that orders the exercises so none misses its deadline, or -1.	Hard8	GreedySorting+2	No attempts yet	1s	512 MB	Judgeable
Flop SortingGiven two permutations of 1..N, output a sequence of flop operations (swap the min and max inside [l,r]) that turns the first permutation into the second, with at most 300000 operations.	Hard8	ImplementationSorting+2	No attempts yet	2s	512 MB	Judgeable
How Many Burgers?Split N burgers with given utilities among three people so that the youngest gets the most he can while not exceeding either senior's total.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	1024 MB	Judgeable
FeastChoose at most K disjoint non-empty subarrays of A so that the total sum of their elements is as large as possible.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	512 MB	Judgeable
Internet ProblemGiven a directed graph, find all vertices lying on every walk from 1 to n, and only on walks from 1 to n, so a walk passes through each chosen vertex exactly once.	Hard8	GraphDFS+2	No attempts yet	5s	512 MB	Judgeable
Fancy FenceCount axis-aligned integer rectangles lying on a histogram of N sections with heights h_i and widths w_i, modulo 1e9+7.	Hard8	StackDivide and conquer+2	No attempts yet	1s	32 MB	Judgeable
ExperimentGiven users with group memberships and pairs of opposed users, decide whether a set of users can be chosen with at most one per group and at least one user from each opposed pair.	Hard8	GraphSimulation+2	No attempts yet	2s	1024 MB	Judgeable
Roadside AdvertisementsOn a weighted tree, for each of Q queries with five distinct nodes, find the total weight of every edge lying on some shortest path between a pair of the five.	Hard8	TreeGraph+2	No attempts yet	1s	512 MB	Judgeable
Rock ClimbingFind the smallest K such that every K-subset of N rocks contains two rocks A, B with A reachable from B by a strictly upward chain of moves, each move bounded by the max slippery rate.	Hard8	GraphGreedy+2	No attempts yet	1s	512 MB	Judgeable
Panda SkiGiven gates with scores and move limits, find the maximum total score of a downward path from peak to base, counting each gate once.	Hard8	GraphDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Cash GapGiven payments with allowed day ranges, decide whether some placement and ordering of the payments forces the balance below zero.	Hard8	GreedySorting+2	No attempts yet	1s	512 MB	Judgeable
Jet TrainsMaintain a growing friendship graph and a growing train-route graph; each query asks how many friends of v lie in v's current connected component.	Hard8	Union-findGraph+2	No attempts yet	2s	512 MB	Judgeable
Flexible SegmentsFor each n up to 10000, decide whether some n consecutive positive integers admit a +1/-1 choice per element preserving the product, and output the start and signs.	Hard8	Number theoryMath+2	No attempts yet	1s	512 MB	Judgeable
Counting in the OrderEach soldier looks left or right and sees past people no taller than the target; count how many soldiers each one sees.	Hard8	StackArray+2	No attempts yet	1s	512 MB	Judgeable
Right-hand obstructionCars arrive in four queues at a crossroad; a front car passes only if the queue on its right is empty, so simulate second by second and report each car's crossing time or -1.	Hard8	SimulationQueue+2	No attempts yet	1s	512 MB	Judgeable
Operation <<Permutation>>Given inequalities between positions of an unknown permutation, find the earliest prefix of the conditions that pins down the permutation uniquely, or -1 if never.	Hard8	GraphTopological sort+2	No attempts yet	1s	512 MB	Judgeable
Shushpanchiks and the CinemaGiven an n by n grid with m blocked seats, choose k consecutive free seats in one row minimizing the sum of Manhattan distances to a target seat.	Hard8	MathIntervals+2	No attempts yet	2s	512 MB	Judgeable
Cipher BreakingOutput a press sequence of at most 2n! buttons so that every permutation of 1..n appears as a contiguous block, for n up to 9.	Hard8	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
A Strange ExhibitGiven the inversion counts of every window of length k in an unknown permutation of 1..n, reconstruct any valid permutation.	Hard8	ImplementationGreedy+2	No attempts yet	2s	512 MB	Judgeable
String ProcessingDecide whether a recursive split-and-swap program can turn string S into T, and if so output the 2^k - 1 bit program.	Hard8	Divide and conquerString+2	No attempts yet	2s	512 MB	Judgeable
Planet NineDecide whether a register can go from a to b using operations that add 9x and operations that delete leading digits, all of which are 1.	Hard8	MathNumber theory+2	No attempts yet	1s	512 MB	Judgeable
Similar ArraysGiven pairs of positions, decide whether there is an array with all distinct values and an array with a repeated value that agree on every listed comparison, and output both arrays.	Hard8	GraphDFS+2	No attempts yet	1s	512 MB	Judgeable
LinearizationFor each query substring whose length is a power of two, find the minimum number of contiguous flips that make it a parity-of-AND pattern; the answer reduces to half the number of adjacent differing pairs after an XOR derivative.	Hard8	Bit manipulationPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
Equal MaximumsCount quadruples of indices i<=j<k<=l where the maximum of a[i..j] equals the maximum of a[k..l], modulo 1e9+7, for n up to 100000.	Hard8	ArrayStack+2	No attempts yet	1s	512 MB	Judgeable
Pandemic 2On a weighted tree where some vertices start infected and the infection spreads along edges at speed one, find the maximum number of uninfected connected components that ever exist at one moment.	Hard8	TreeDFS+2	No attempts yet	1s	512 MB	Judgeable
Heavy BurgerMaintain a string of parentheses under range flips, and for each query on a substring report the minimum number of characters to insert so the substring becomes a balanced parenthesis sequence.	Hard8	Segment treeString matching+2	No attempts yet	3s	1024 MB	Judgeable
BusSimulate bus boarding with passengers sitting in the closest free seat or standing over an occupied one, and choose Anton's seat minimizing the total time someone stands over him.	Hard8	SimulationGreedy+2	No attempts yet	2s	512 MB	Judgeable
«Exclusive or» Strikes BackFor each query with a and n up to 1e18, find the smallest non-negative b such that a xor b is divisible by n.	Hard8	Bit manipulationNumber theory+2	No attempts yet	2s	512 MB	Judgeable
SpeedingGiven n road segments with speed limits and lengths, plus m speeding ranges with fines, find for each car the maximum fine guaranteed from its entry and exit times.	Hard8	Binary searchGreedy+2	No attempts yet	2s	512 MB	Judgeable
PostersOn a cycle of n posters, choose a subset with no run of four consecutive chosen positions, maximizing total colorfulness, and answer after each of q point updates.	Hard8	Dynamic programmingSegment tree+2	No attempts yet	2s	512 MB	Judgeable
QuadtreeGiven a 2^n by 2^n binary matrix and a budget k, flip at most k entries so the resulting matrix has a quadtree with the fewest possible cells.	Hard8	TreeDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
GarlandDelete elements from a binary string so the remaining string is beautiful (beads left of each 1 equal beads right of it, bounded by neighboring 1s), maximizing length.	Hard8	Dynamic programmingString+2	No attempts yet	2s	512 MB	Judgeable
Broken Line 04Construct an axis-aligned broken line starting at the origin that passes through every given dot, minimizing the number of segments for partial credit.	Hard8	SortingGreedy+2	No attempts yet	0.1s	512 MB	Judgeable
Broken Line 05Given n points with distinct x and y coordinates, build a horizontal/vertical polyline from the origin covering all points, minimizing the number of segments.	Hard8	GreedySorting+2	No attempts yet	0.1s	512 MB	Judgeable
Broken Line 08Output-only task: build a horizontal and vertical broken line from the origin that touches every given dot, minimizing the number of segments for partial score.	Hard8	SortingGreedy+2	No attempts yet	0.1s	512 MB	Judgeable
Handcrafted GiftColor n beads red or blue so that every given interval contains exactly x[i] distinct colors (x[i] is 1 or 2), or report that no coloring works.	Hard8	GreedySorting+2	No attempts yet	1s	1024 MB	Judgeable
Painting SquaresPaint squares black or white and choose the smallest k so that the color pattern in any window of length k, together with whether it runs off the row, always identifies the window's start.	Hard8	StringCombinatorics+2	No attempts yet	4s	1024 MB	Judgeable
Carnival TicketsGiven n sorted lists (n even), choose k disjoint transversal sets of one element per list to maximize the sum over rounds of the minimized total absolute deviation from a best center b.	Hard8	GreedySorting+2	No attempts yet	2s	1024 MB	Judgeable
Counting MushroomsGiven that mushroom 0 is species A, use a machine that counts adjacent differing pairs in a queried row to determine how many of the n mushrooms are species A.	Hard8	ImplementationMath+2	No attempts yet	2s	1024 MB	Judgeable
StationsLabel the stations of a tree so that a station holding a packet can pick the correct next hop knowing only its own label, the target label, and its neighbours' labels.	Hard8	TreeDFS+2	No attempts yet	20s	1024 MB	Judgeable
Sea BattleTwo fleets of point ships move on an infinite grid at periodic step intervals; find the earliest step at which any ship from one fleet shares a cell with any ship from the other, or -1.	Hard8	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Turtles in the PondGiven a growing connected set of grid cells, after each insertion decide whether every pair can be joined by a path that uses only two fixed directions of movement.	Hard8	GraphUnion-find+2	No attempts yet	2s	512 MB	Judgeable
Painting the FenceGiven n segment lengths on a cyclic fence of k boards, order the painters and place each segment to maximize the minimum number of boards each painter is first to paint.	Hard8	GreedyBinary search+2	No attempts yet	2s	512 MB	Judgeable
Rotating PlateGiven a simple polygon pinned at its first vertex, find for each of m external points the maximum clockwise and counterclockwise rotation before the polygon hits that point.	Hard8	GeometryBinary search+2	No attempts yet	2s	512 MB	Judgeable
Strange CityChoose a subset of edges in an undirected graph so that every vertex has odd degree, or report that no such subset exists.	Hard8	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
Min-hashingGiven a graph with a distinct label per node, repeatedly replace each node's value by the minimum value among its neighbors and find the largest number of node pairs sharing a value at any iteration.	Hard8	GraphSimulation+2	No attempts yet	1s	1024 MB	Judgeable
Remote ControlGiven one blocked cell at the origin and a fixed command string of N moves, find the final cell for each of Q starting positions.	Hard8	SimulationPrefix sum+2	No attempts yet	2s	1024 MB	Judgeable
Bit StringCount bit strings of length n that contain P1 as a substring but avoid P2, modulo 1,000,000,007.	Hard8	Dynamic programmingString matching+2	No attempts yet	1.5s	1024 MB	Judgeable
Trading SystemGiven n integers and k, list the k largest sums among all contiguous subarrays, in non-increasing order.	Hard8	HeapPrefix sum+2	No attempts yet	1s	512 MB	Judgeable
Counting the Number of TreesCount, modulo 1e9+7, the binary search trees on keys 1..N that the insertion procedure can produce with height at most K.	Hard8	Dynamic programmingTree+2	No attempts yet	2s	256 MB	Judgeable
Nowruz 2Given a grid with rocks, block some free cells with bushes so the remaining free cells form a tree with as many degree-one cells as possible.	Hard8	GraphTree+2	No attempts yet	1s	512 MB	Judgeable
Nowruz 3Turn a grid with rocks into a tree-shaped maze by blocking cells with bushes so that many free cells have exactly one free neighbor.	Hard8	GraphTree+2	No attempts yet	1s	512 MB	Judgeable
Nowruz 9Given a grid with rocks, plant bushes so the remaining free cells form a tree, maximizing the number of cells that have exactly one free neighbor.	Hard8	GraphTree+2	No attempts yet	1s	512 MB	Judgeable
Nowruz 10Output-only task: given a grid with rocks, plant bushes so the free cells form a tree, maximizing the number of free cells with exactly one free neighbor.	Hard8	GraphTree+2	No attempts yet	1s	512 MB	Judgeable
Toy TrainOn a directed graph with charging stations, two players alternately fix the outgoing edge of each newly visited vertex; decide for every start whether Arezou can force the train to keep moving forever.	Hard8	GraphGame theory+2	No attempts yet	2s	512 MB	Judgeable
Cup of JamshidFind a hidden point in a square using queries that return \|x-p\| XOR \|y-q\| for chosen points, staying within a query budget.	Hard8	Bit manipulationBinary search+2	No attempts yet	1s	512 MB	Judgeable
Last SupperWrite two programs: one reads the request sequence and outputs a short bit string, the other uses only that string plus online requests to make optimal eviction choices.	Hard8	GreedyImplementation+2	No attempts yet	2s	512 MB	Judgeable
Card ShuffleGiven an odd deck size N and positions A and B, find the shortest sequence of X and Y shuffles that moves the card at position A to position B.	Hard8	ImplementationMath+2	No attempts yet	1s	256 MB	Judgeable
Vista 1Given up to a million points in the plane, output a cyclic tour that visits every point once and returns to the start, judged by total Euclidean length.	Hard8	GeometryGreedy+2	No attempts yet	0.1s	128 MB	Judgeable
Vista 2Given up to a million points in the plane, output a cyclic tour visiting every point whose total Euclidean length is at most a constant factor times the optimal tour.	Hard8	GeometryGreedy+2	No attempts yet	0.1s	128 MB	Judgeable
Hero Loves Powers of Two! Hero Loves Powers of Two!Given up to 2.2M numbers, delete at most one, represent the rest as sums of distinct powers of two, XOR the resulting exponent sets, and print twice the maximum XOR value.	Hard8	Bit manipulationGreedy+2	No attempts yet	2.2s	222 MB	Judgeable
Since It Has Come to This, Become the Memorization KingAfter M rounds where a chosen student splits from their mentor and takes their whole subtree into a new group, answer K queries about whether two students share a group after round A.	Hard8	TreeDFS+2	No attempts yet	2s	1024 MB	Judgeable
Dessert CaféOn a weighted tree with k marked apartment nodes, count the nodes p for which some marked node z is strictly closer to p than to every other node.	Hard8	TreeGraph+2	No attempts yet	1s	512 MB	Judgeable
Imprecise ComputerGiven n and a sequence of n nonnegative integers, decide whether it can be the difference sequence of a double round-robin tournament played on {1,...,n} where each comparison may be answered arbitrarily when the two numbers differ by one.	Hard8	GreedyMath+1	No attempts yet	1s	512 MB	Judgeable
SwitchesGiven an N by N 0/1 matrix linking switches to lights, decide whether each light can be lit alone, and if so print the switches to press for every light.	Hard8	MathMatrix+2	No attempts yet	1s	512 MB	Judgeable
Bubble BubbleFor each index, replace that one element with any real number and report the minimum number of adjacent swaps bubble sort needs to sort the resulting array.	Hard8	SortingPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
Trees Hate Queries~Maintain a sparse array over positions up to 1e9, apply range additions, and answer queries for the sum of a range after the first k updates.	Hard8	Segment treePrefix sum+2	No attempts yet	1s	512 MB	Judgeable
Icpcan AlphabetCount the total orders on n letters that make two nested min/max expressions evaluate to the same letter.	Hard8	Dynamic programmingBrute force+2	No attempts yet	3s	512 MB	Judgeable
Nunchucks ShopGiven n and k, find the minimum number of binary strings of length n such that every length-n binary string pair with total k ones can be formed by joining two stored sticks, each usable in either orientation.	Hard8	CombinatoricsMath+2	No attempts yet	2s	512 MB	Judgeable