Problems

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Total results21,491 problems

Kaisa - SurvivalHard8
Tree, DFS +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
VlakHard8
Trie, Game theory +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Strange StringsHard8
String, Hash map +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
To Fish or Not to FishHard8
Greedy, Sorting +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
CCTV ControlHard8
Array, Implementation +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Dao and Dizzy's DateHard8
Dynamic programming, Math +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Complex QueriesHard8
Graph, Bit manipulation +2No attempts yetTime limit2.5sMemory limit1024 MB
Judgeable
Painting PipsHard8
Math, Dynamic programming +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Permutations on the Road: BobHard8
Divide and conquer, Math +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Neural NetworksHard8
Dynamic programming, Combinatorics +2No attempts yetTime limit4sMemory limit1024 MB
Judgeable
Broken lineHard8
Greedy, Bit manipulation +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Game On BoardHard8
Math, Combinatorics +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
InvHard8
Combinatorics, Dynamic programming +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Walking PlanHard8
Graph, Shortest path +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Partition NumberHard8
Dynamic programming, Combinatorics +2No attempts yetTime limit3sMemory limit256 MB
Judgeable
All your base are belong to usHard8
Geometry, Binary search +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Universal and Existential QuantifiersHard8
Greedy, Sorting +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Lotte Giants and GahuiHard8
Math, Number theory +2No attempts yetTime limit0.5sMemory limit512 MB
Judgeable
Just Buy Your Drinks, PleaseHard8
Binary search, Sorting +2No attempts yetTime limit3sMemory limit1024 MB
Judgeable
Necklace ConstructionHard8
Dynamic programming, String +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Moon and SunHard8
Math, Combinatorics +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Cul-De-Sac ParadesHard8
Tree, DFS +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Shopping ChangesHard8
Divide and conquer, Sorting +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Down We DigHard8
Game theory, Dynamic programming +2No attempts yetTime limit5sMemory limit512 MB
Judgeable
Three MachinesHard8
Math, Number theory +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Subway MapHard8
Minimum spanning tree, Union-find +2No attempts yetTime limit4sMemory limit1024 MB
Judgeable
Ostap and chairsHard8
Geometry, Binary search +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
Combine The GearsHard8
Math, Number theory +2No attempts yetTime limit2sMemory limit256 MB
Judgeable
Arrange and Count!Hard8
Combinatorics, Math +2No attempts yetTime limit5sMemory limit512 MB
Judgeable
The LocksmithHard8
Math, Number theory +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Space Station PromenadeHard8
Dynamic programming, Prefix sum +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
SkidorHard8
Sliding window, Heap +2No attempts yetTime limit7sMemory limit1024 MB
Judgeable
Christmas ShoppingHard8
Dynamic programming, Bit manipulation +2No attempts yetTime limit4sMemory limit1024 MB
Judgeable
Decorative DominoesHard8
Graph, DFS +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
XOR Data StructureHard8
Trie, Bit manipulation +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
MapleStoryHard8
Dynamic programming, Shortest path +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Space StationsHard8
Union-find, Geometry +2No attempts yetTime limit2.5sMemory limit1024 MB
Judgeable
Divisor RitualHard8
Bit manipulation, Dynamic programming +2No attempts yetTime limit1.75sMemory limit1024 MB
Judgeable
Maskpunk 2077Hard8
Segment tree, Binary search +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
The Formula Sicheol LovedHard8
Number theory, Math +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
KakaoTalkHard8
Geometry, Hash map +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Game Developer SeungheeHard8
Math, Number theory +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Dance MoovesHard8
Graph, Simulation +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
No Time to PaintHard8
Prefix sum, Stack +2No attempts yetTime limit5sMemory limit512 MB
Judgeable
Safety InspectionHard8
Binary search, Greedy +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Growing Vegetables is Fun 4Hard8
Dynamic programming, Greedy +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Drawing CirclesHard8
Geometry, Sorting +2No attempts yetTime limit5sMemory limit1024 MB
Judgeable
Perfect Path PatrolHard8
Tree, Greedy +2No attempts yetTime limit4sMemory limit1024 MB
Judgeable
Slow DownHard8
Graph, Shortest path +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Hallway and ButlerHard8
Tree, DFS +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Power LinkHard8
Math, Implementation +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Jumping StonesHard8
Intervals, Sorting +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Healthy LifestyleHard8
Graph, DFS +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Presidential GameHard8
Game theory, Dynamic programming +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Galatea's DietHard8
Combinatorics, Math +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Flip and CombosHard8
Segment tree, Divide and conquer +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Dams in DistressHard8
Tree, DFS +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
GameHard8
Dynamic programming, Probability +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
GPAHard8
Dynamic programming, Greedy +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
Local MaximaHard8
Combinatorics, Math +1No attempts yetTime limit4sMemory limit512 MB
Judgeable
MinerHard8
Intervals, Sorting +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
RobotHard8
Simulation, Prefix sum +2No attempts yetTime limit3sMemory limit512 MB
Judgeable
Biological Software UtilitiesHard8
Combinatorics, Tree +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Bitonic OrderingHard8
Sorting, Greedy +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Exciting TournamentHard8
Dynamic programming, Greedy +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Kth SubtreeHard8
Tree, Dynamic programming +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Longest Common Subsequence of PermutationsHard8
Dynamic programming, Bit manipulation +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Rainbow NumbersHard8
Dynamic programming, Math +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Agamemnon's OdysseyHard8
Tree, Greedy +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Basic BasisHard8
Math, Bit manipulation +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Full Depth Morning ShowHard8
Tree, DFS +2No attempts yetTime limit3sMemory limit1024 MB
Judgeable
Solar EnergyHard8
Geometry, Sorting +2No attempts yetTime limit9sMemory limit1024 MB
Judgeable
Magic ScaleHard8
Heap, Sorting +2No attempts yetTime limit3sMemory limit512 MB
Judgeable
Paper SnowflakesHard8
Simulation, Sorting +2No attempts yetTime limit5sMemory limit1024 MB
Judgeable
Antimatter RainHard8
Sorting, Segment tree +2No attempts yetTime limit7sMemory limit1024 MB
Judgeable
RestaurantsHard8
Greedy, Hash map +2No attempts yetTime limit3sMemory limit2048 MB
Judgeable
Modern Art 3Hard8
Dynamic programming, Intervals +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Year of the CowHard8
Dynamic programming, Greedy +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Fakes and ShidgetHard8
Binary search, Greedy +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Ah, It's Yesterday Once MoreHard8
Greedy, Math +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
FireworksHard8
Math, Probability +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Just Another Game of StonesHard8
Segment tree, Game theory +2No attempts yetTime limit5sMemory limit512 MB
Judgeable
Monster HunterHard8
Tree, Dynamic programming +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Miner SeokHard8
Sorting, Binary search +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
FactorialHard8
Number theory, Math +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Stern's SequenceHard8
Math, Number theory +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Teleport TravelHard8
Tree, Dynamic programming +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
MafiaHard8
Graph, Union-find +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Fibonacci StringsHard8
String, Dynamic programming +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Messy kangaroo babiesHard8
String, Dynamic programming +2No attempts yetTime limit5sMemory limit1024 MB
Judgeable
Social DistanseringHard8
Binary search, Greedy +2No attempts yetTime limit3sMemory limit1024 MB
Judgeable
Flying a DroneHard8
Dynamic programming, Binary search +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
BowlingHard8
Greedy, Sorting +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
DecompressionHard8
String, Sorting +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Bus PassHard8
Graph, BFS +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Dice Password SecurityHard8
Dynamic programming, String matching +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
TheatreHard8
Dynamic programming, Bit manipulation +2No attempts yetTime limit5sMemory limit1024 MB
Judgeable
Computational IchthyologyHard8
Greedy, Simulation +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
About Love...Hard8
Geometry, Binary search +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
NumberHard8
Math, Number theory +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Kaisa - SurvivalGiven a rooted tree, take the LCA of every ordered pair of vertices (including x=y), collect all N^2 results into one multiset, sort it, then print the sum of values at odd and even positions.	Hard8	TreeDFS+2	No attempts yet	1s	1024 MB	Judgeable
VlakTwo players alternately append letters so the growing word stays a prefix of a word in the mover's own song; decide who wins under optimal play.	Hard8	TrieGame theory+2	No attempts yet	1s	512 MB	Judgeable
Strange StringsGiven a string s, count the number of distinct substrings t such that the set of substrings of t equals the set of subsequences of t.	Hard8	StringHash map+2	No attempts yet	1s	512 MB	Judgeable
To Fish or Not to FishChoose fishing points to visit and bases to sell at along a river, paying fuel only while moving upstream, to maximize profit.	Hard8	GreedySorting+2	No attempts yet	1s	512 MB	Judgeable
CCTV ControlGiven an n by m grid of 1s and 2s that can be cyclically shifted in rows and columns, maximize the number of 2x2 blocks whose four cells all match.	Hard8	ArrayImplementation+2	No attempts yet	2s	512 MB	Judgeable
Dao and Dizzy's DateWalk on a line of N places for T minutes starting and ending at place 1, gaining h[j] whenever you move to place j, and maximize total happiness.	Hard8	Dynamic programmingMath+2	No attempts yet	1s	1024 MB	Judgeable
Complex QueriesGiven a connected weighted undirected graph, define d(u,v) as the maximum XOR weight of any walk from u to v; answer queries asking for the XOR of d(i,j) over all pairs l<=i<j<=r.	Hard8	GraphBit manipulation+2	No attempts yet	2.5s	1024 MB	Judgeable
Painting PipsGiven N dice and M total pips to distribute across faces, find the maximum expected product of the rolled values.	Hard8	MathDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
Permutations on the Road: BobGiven up to N queries returning the inversion count within a subarray, reconstruct the hidden permutation of length N.	Hard8	Divide and conquerMath+2	No attempts yet	2s	1024 MB	Judgeable
Neural NetworksCount labeled layered digraphs in which every node lies on some directed path from layer 1 to layer N, modulo 998244353.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	4s	1024 MB	Judgeable
Broken lineAssign each of the up to 16 distinct letters a fixed arrow (right or up) so the area under the resulting monotone staircase path is maximized.	Hard8	GreedyBit manipulation+2	No attempts yet	1s	512 MB	Judgeable
Game On BoardCount the minimal initial boards (with the fewest black cells) on an n by m grid from which the closure rule paints every cell black, modulo 998244353.	Hard8	MathCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
InvCount involutions of n elements with exactly k inversions and report the count modulo 2.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Walking PlanFor each query, find the minimum total length of a walk from s to t that uses at least k edges in a directed weighted graph.	Hard8	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
Partition NumberCount partitions of m into nondecreasing positive parts, where a given set of n values is forbidden as a part, modulo 1e9+7.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	3s	256 MB	Judgeable
All your base are belong to usChoose any point in the plane to minimize the sum of distances to the K farthest bases, and output that minimum sum.	Hard8	GeometryBinary search+2	No attempts yet	2s	512 MB	Judgeable
Universal and Existential QuantifiersGiven N half-open intervals whose union is [0,L), find the fewest intervals whose union is [0,L) and the fewest k such that any k intervals already cover [0,L).	Hard8	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
Lotte Giants and GahuiCount length-n sequences of positive integers whose gcd is G and lcm is L, printing each answer modulo 1e9+7.	Hard8	MathNumber theory+2	No attempts yet	0.5s	512 MB	Judgeable
Just Buy Your Drinks, PleaseEach query asks for the highest taste threshold t such that liquids with d_i >= t can supply at least L liters within budget g, respecting per-liquid caps.	Hard8	Binary searchSorting+2	No attempts yet	3s	1024 MB	Judgeable
Necklace ConstructionGiven a target string of up to 300 lowercase letters, find the minimum number of edit and copy-reverse operations to build it from an empty buffer necklace.	Hard8	Dynamic programmingString+2	No attempts yet	2s	512 MB	Judgeable
Moon and SunCount indices i where changing A_i to some other integer in [-100000, 100000] makes the single element of the N-fold difference sequence a multiple of 235813.	Hard8	MathCombinatorics+2	No attempts yet	1s	512 MB	Judgeable
Cul-De-Sac ParadesGiven a weighted tree, choose edge-disjoint paths that each start and end at a leaf, maximizing the total weight of the edges used.	Hard8	TreeDFS+2	No attempts yet	1s	512 MB	Judgeable
Shopping ChangesGiven a fixed change sequence and several wallets, find for each wallet the insertion position that minimizes the total inversion count after inserting the change block.	Hard8	Divide and conquerSorting+2	No attempts yet	2s	512 MB	Judgeable
Down We DigGiven n 8-character steps, for each prefix of steps determine the winner of a token game where a move from step i to j is legal when the Hamming similarity of the two steps is at least j-i.	Hard8	Game theoryDynamic programming+2	No attempts yet	5s	512 MB	Judgeable
Three MachinesCount pairs (a,b) with 1 <= a < b <= m from which three rewrite operations on integer pairs can generate every card (1, a_i).	Hard8	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Subway MapGiven a connected graph where some edge weights are unknown and a marked edge subset connects every node to node 1, find the minimum possible weight of each unknown edge so that the marked edges form a minimum spanning tree.	Hard8	Minimum spanning treeUnion-find+2	No attempts yet	4s	1024 MB	Judgeable
Ostap and chairsGiven N x-coordinates and N y-coordinates, find real k and b minimizing the sum of \|x_i - (k*y_i + b)\|.	Hard8	GeometryBinary search+2	No attempts yet	1s	256 MB	Judgeable
Combine The GearsGiven a budget b, choose gear sizes with total cost at most b to maximize the number of distinct pointer-direction tuples, output as a natural logarithm.	Hard8	MathNumber theory+2	No attempts yet	2s	256 MB	Judgeable
Arrange and Count!Given a sequence, count modulo 1e9+7 how many distinct orderings the prefix-reversal-then-append operation can produce, over multiple test cases.	Hard8	CombinatoricsMath+2	No attempts yet	5s	512 MB	Judgeable
The LocksmithMaintain a dynamic set of arithmetic progressions (a mod b) and answer point queries asking whether any active progression contains a given lock number.	Hard8	MathNumber theory+2	No attempts yet	1s	1024 MB	Judgeable
Space Station PromenadeA circular station has m windows on given modules that must be visited in order from module 1 and back; minimize total travel subject to equal clockwise and counterclockwise distances.	Hard8	Dynamic programmingPrefix sum+2	No attempts yet	1s	1024 MB	Judgeable
SkidorFind an L by L square with no trees whose height range is minimal, breaking ties by smallest top row then left column.	Hard8	Sliding windowHeap+2	No attempts yet	7s	1024 MB	Judgeable
Christmas ShoppingAssign each of K friends a distinct present from N items to maximize the total of the chosen liking values a[i][j].	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	4s	1024 MB	Judgeable
Decorative DominoesGiven an arrangement of n dominoes on a grid, assign each of the 2n ends an integer (0 to 10^6) so that touching ends share a number and no number appears more than twice, or report impossible.	Hard8	GraphDFS+2	No attempts yet	1s	512 MB	Judgeable
XOR Data StructureMaintain a multiset under add, delete-all-min, delete-all-max, and queries for the element minimizing or maximizing v XOR s.	Hard8	TrieBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
MapleStoryGiven N hunting grounds with entry experience thresholds and per-minute rates, plus travel times, find the maximum experience obtainable within T minutes.	Hard8	Dynamic programmingShortest path+2	No attempts yet	2s	1024 MB	Judgeable
Space StationsEach station is a line segment, two axis-aligned or point contact connects them; for each query decide if two stations lie in the same connected component.	Hard8	Union-findGeometry+2	No attempts yet	2.5s	1024 MB	Judgeable
Divisor RitualGiven N cards with digits 1 to 9, count permutations where the last card's digit divides the number formed by the first N-1 cards, and output that probability.	Hard8	Bit manipulationDynamic programming+2	No attempts yet	1.75s	1024 MB	Judgeable
Maskpunk 2077Houses sit on a line with mask costs and edge travel times; handle point updates to travel times and queries for the cheapest mask reachable from a house within m minutes.	Hard8	Segment treeBinary search+2	No attempts yet	1s	1024 MB	Judgeable
The Formula Sicheol LovedCompute two nested-sum formulas involving gcd and lcm over all index pairs up to N, each reduced modulo a prime K, for N up to 10^6.	Hard8	Number theoryMath+2	No attempts yet	1s	1024 MB	Judgeable
KakaoTalkGiven N distinct lines, count pairs that intersect (meet at exactly one point), so parallel distinct lines and coincident lines do not count.	Hard8	GeometryHash map+2	No attempts yet	2s	1024 MB	Judgeable
Game Developer SeungheePerform M operations on sequence A, each adding Bi to all elements then deleting multiples of 7 unless that would empty the sequence, and report the final sequence modulo 1e9+7.	Hard8	MathNumber theory+2	No attempts yet	1s	1024 MB	Judgeable
Dance MoovesGiven K position swaps repeated forever, count for each cow how many distinct positions in the line she ever occupies.	Hard8	GraphSimulation+2	No attempts yet	1s	512 MB	Judgeable
No Time to PaintGiven a target string of 26 ordered colors and Q queries, each leaving one interval unpainted, find the minimum number of brush strokes to paint the rest, where a stroke paints a contiguous range one color and no lighter color may cover a darker one.	Hard8	Prefix sumStack+2	No attempts yet	5s	512 MB	Judgeable
Safety InspectionK carpenters start at coordinate 0 on a line and must finish inspecting Bi items at facility i located at coordinate Ai, where each minute allows one unit of movement or one inspection; find the minimum total time.	Hard8	Binary searchGreedy+2	No attempts yet	2s	1024 MB	Judgeable
Growing Vegetables is Fun 4Given N heights in a row, each operation adds 1 to a contiguous interval; find the minimum number of operations so the final sequence strictly increases then strictly decreases.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	512 MB	Judgeable
Drawing CirclesGiven up to 2000 circles drawn in order, each new circle erases the interior of everything already there; find the total length of circumference still visible.	Hard8	GeometrySorting+2	No attempts yet	5s	1024 MB	Judgeable
Perfect Path PatrolGiven a tree whose edges each need to lie on exactly p patrol paths, find the minimum number of paths (each between two junctions) that achieve all edge demands.	Hard8	TreeGreedy+2	No attempts yet	4s	1024 MB	Judgeable
Slow DownRaise some edge weights in a connected undirected graph so the shortest path from node 1 to node N grows by at least 1, paying the total increase, and minimize that cost.	Hard8	GraphShortest path+2	No attempts yet	1s	512 MB	Judgeable
Hallway and ButlerCount the closed walks from room 1 that traverse each edge of a weighted tree exactly w_i times, modulo 998244353.	Hard8	TreeDFS+2	No attempts yet	1s	512 MB	Judgeable
Power LinkMaintain generator powers under point updates and answer queries, each asking for the sum of pairwise products of the generators feeding one appliance.	Hard8	MathImplementation+2	No attempts yet	1s	512 MB	Judgeable
Jumping StonesMaintain a set of present stones under insertions and deletions and answer the minimum jump energy between two present stones, where jumping a gap of length g costs (g-1)^2.	Hard8	IntervalsSorting+2	No attempts yet	2s	512 MB	Judgeable
Healthy LifestyleGiven a connected undirected graph, answer queries asking whether two edge-disjoint paths exist between a pair of vertices.	Hard8	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
Presidential GameTwo players alternately merge 2 to K adjacent elements, John by sum and Preston by XOR, until one value remains; decide who wins when John needs the final value odd.	Hard8	Game theoryDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Galatea's DietCount sequences of M candy types from N choices, where a few days have fixed types, so that no two consecutive days share a type, modulo 1e9+7.	Hard8	CombinatoricsMath+2	No attempts yet	1s	512 MB	Judgeable
Flip and CombosMaintain a binary array under range flip operations and answer queries for the longest run of equal bits inside a subarray.	Hard8	Segment treeDivide and conquer+2	No attempts yet	2s	512 MB	Judgeable
Dams in DistressGiven a rooted tree of dams with capacities and current water, find the minimum rain at one node (or the root) that sends at least w water to the root.	Hard8	TreeDFS+2	No attempts yet	2s	1024 MB	Judgeable
GameA robot starts uniformly at random in an array and may stop for A_i or gamble a fair step left or right; maximize the expected score, output modulo 998244353.	Hard8	Dynamic programmingProbability+2	No attempts yet	1s	256 MB	Judgeable
GPAGiven n courses with original grade A_i and altered grade B_i, pick a subset to change so the number of days where the new grade falls below the running average of earlier grades is minimized.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	256 MB	Judgeable
Local MaximaCount permutations of 1 to n*m in an n by m grid that have exactly one local maximum, where a cell is a local maximum if it is at least every other cell in its row and column, modulo a prime P.	Hard8	CombinatoricsMath+1	No attempts yet	4s	512 MB	Judgeable
MinerGiven n intervals and m points, count the nonempty subsets of intervals whose intersection contains at least one of the given points, modulo 998244353.	Hard8	IntervalsSorting+2	No attempts yet	1s	256 MB	Judgeable
RobotFor each command in a robot's move string, compute the total score the robot would earn if that single command were deleted, where each visit to a cell scores based on visit count and cell coordinates.	Hard8	SimulationPrefix sum+2	No attempts yet	3s	512 MB	Judgeable
Biological Software UtilitiesCount the labeled trees on n vertices that have a perfect matching, modulo 998244353, for n up to 10^6.	Hard8	CombinatoricsTree+2	No attempts yet	1s	512 MB	Judgeable
Bitonic OrderingGiven a permutation of distinct cards, find the minimum number of adjacent swaps needed to make the sequence first increasing then decreasing (bitonic).	Hard8	SortingGreedy+2	No attempts yet	2s	512 MB	Judgeable
Exciting TournamentGiven players with distinct skills and per-player game limits, choose any knockout bracket and report the minimum and maximum total XOR excitement over all games.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	512 MB	Judgeable
Kth SubtreeGiven a tree with n up to 5000 nodes and a rank K, find the size of the Kth smallest connected subgraph (subtree) by node count, or report -1.	Hard8	TreeDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Longest Common Subsequence of PermutationsGiven n permutations of the first k uppercase letters, find the length of the longest sequence that is a subsequence of every one of the n strings.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	1s	512 MB	Judgeable
Rainbow NumbersCount integers between two huge bounds (up to 100000 digits) whose decimal digits never repeat consecutively, modulo 998244353.	Hard8	Dynamic programmingMath+2	No attempts yet	1s	512 MB	Judgeable
Agamemnon's OdysseyGiven a weighted tree and a limit k, find a walk (any start and end) that uses no edge more than k times and collects the weight of each edge only on its first traversal, maximizing total collected weight.	Hard8	TreeGreedy+2	No attempts yet	1s	1024 MB	Judgeable
Basic BasisGiven n bit vectors of 4k bits, for each of m query vectors find the smallest prefix index i such that some nonempty subset of the first i vectors XORs to the query.	Hard8	MathBit manipulation+2	No attempts yet	1s	512 MB	Judgeable
Full Depth Morning ShowFor each city u in a weighted tree, compute the sum over all other cities v of (t_u + t_v) times the distance between u and v.	Hard8	TreeDFS+2	No attempts yet	3s	1024 MB	Judgeable
Solar EnergyGiven N stars each contributing a clipped triangular amount of energy as a function of launch angle, find the angle maximizing the total contribution.	Hard8	GeometrySorting+2	No attempts yet	9s	1024 MB	Judgeable
Magic ScaleGiven N positive weights, list the K smallest distinct subset sums in increasing order, and for each sum output one subset of weights that achieves it.	Hard8	HeapSorting+2	No attempts yet	3s	512 MB	Judgeable
Paper SnowflakesFold a paper strip back and forth at decreasing distances from the loose end, cut it at M positions, and report the total paper length in each resulting pile.	Hard8	SimulationSorting+2	No attempts yet	5s	1024 MB	Judgeable
Antimatter RainDroplets fall straight down; each horizontal sensor disintegrates along with all droplets that reach it, and the rest pass through. For every droplet, report the y-coordinate where it dies, or 0.	Hard8	SortingSegment tree+2	No attempts yet	7s	1024 MB	Judgeable
RestaurantsFind a stable matching of customers to restaurants with capacities, where both sides have preference lists, and output the assigned customers.	Hard8	GreedyHash map+2	No attempts yet	3s	2048 MB	Judgeable
Modern Art 3Given a 1D painting of N colors, find the minimum number of brush strokes (each painting one interval in one color, later strokes over earlier ones) needed to reproduce it.	Hard8	Dynamic programmingIntervals+2	No attempts yet	1s	512 MB	Judgeable
Year of the CowGiven N ancestor years on a line and at most K time jumps between multiples of 12 (Ox years), find the minimum total travel time to visit every ancestor and return to year 0.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	512 MB	Judgeable
Fakes and ShidgetEach of n characters offers two quests with given times and rewards; find the maximum long-run gold per minute when the character each round is chosen uniformly at random.	Hard8	Binary searchGreedy+2	No attempts yet	2s	512 MB	Judgeable
Ah, It's Yesterday Once MoreConstruct a legal grid (tree of empty cells, at least two, at most 20x20) so that a random string of 50000 UDLR moves fails to merge all kangaroos at least 25% of the time.	Hard8	GreedyMath+2	No attempts yet	1s	512 MB	Judgeable
FireworksEach firework takes n minutes and is perfect with probability p/10000; lighting all made so far takes m minutes and ends the game if any is perfect. Find the minimum expected total time under an optimal stopping strategy.	Hard8	MathProbability+2	No attempts yet	2s	512 MB	Judgeable
Just Another Game of StonesMaintain an array under range chmax updates, and for each query count first moves that win the Nim game on a subarray plus one extra pile.	Hard8	Segment treeGame theory+2	No attempts yet	5s	512 MB	Judgeable
Monster HunterOn a rooted tree, killing a vertex costs its hp plus the hp of its living children; with up to m free kills by spell, find the minimum total power for every m from 0 to n.	Hard8	TreeDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Miner SeokChoose an axis-aligned rectangle anchored at (0,0) whose interior minerals number at most C, maximizing the total beauty of the minerals inside it.	Hard8	SortingBinary search+2	No attempts yet	1s	512 MB	Judgeable
FactorialOutput a single integer N between 7 and 10^14 that maximizes a score based on how close N! times a power of ten lands to an integer, avoiding floating-point traps.	Hard8	Number theoryMath+2	No attempts yet	1s	512 MB	Judgeable
Stern's SequenceGiven a reduced fraction p/q, find the index k in Stern's diatomic sequence where b(k)=p and b(k+1)=q, output modulo 998244353.	Hard8	MathNumber theory+2	No attempts yet	1s	512 MB	Judgeable
Teleport TravelA perfect binary tree of height N is given; starting from node 2K-1, find the minimum number of teleports needed to visit every node, taken modulo 1e9+7.	Hard8	TreeDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
MafiaGiven accusations of honesty or corruption between cops, count for each queried C the number of size-C corrupt sets consistent with all accusations.	Hard8	GraphUnion-find+2	No attempts yet	1s	1024 MB	Judgeable
Fibonacci StringsSum the orders (counts of letter a) of every substring of X that is a Fibonacci string, meaning it has no two adjacent a's, counting each occurrence separately.	Hard8	StringDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
Messy kangaroo babiesGiven a word S and a list of candidate synonyms, count how many are subsequences of S that can be embedded in at least two different ways.	Hard8	StringDynamic programming+2	No attempts yet	5s	1024 MB	Judgeable
Social DistanseringGiven N students, K queue positions, and M disjoint forbidden intervals, find the largest D such that all N students can be placed at pairwise distance at least D.	Hard8	Binary searchGreedy+2	No attempts yet	3s	1024 MB	Judgeable
Flying a DronePick batteries within a budget to maximize total energy divided by combined drone and battery weight.	Hard8	Dynamic programmingBinary search+2	No attempts yet	2s	1024 MB	Judgeable
BowlingEach player has G scores that may be permuted independently; for every player find the minimum and maximum number of games they can win, where a win means a strictly higher score than all other players in that game.	Hard8	GreedySorting+2	No attempts yet	1s	1024 MB	Judgeable
DecompressionInvert a Burrows-Wheeler style permutation by reconstructing the sorted rotation table from the last-column string, then rotate the result so the period comes first.	Hard8	StringSorting+2	No attempts yet	1s	1024 MB	Judgeable
Bus PassGiven an undirected zone graph and several ordered bus routes, find the center zone and smallest star radius covering every route.	Hard8	GraphBFS+2	No attempts yet	1s	1024 MB	Judgeable
Dice Password SecurityGiven a dictionary of words with no word a substring of another, count how many n-word concatenations have each queried total length.	Hard8	Dynamic programmingString matching+2	No attempts yet	1s	1024 MB	Judgeable
TheatreTwo technicians at opposite wings must switch stage lights between acts, one turning lights on and one off, and each act change must wait for the slower of the two to finish moving; minimize the total break time.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	5s	1024 MB	Judgeable
Computational IchthyologyAquariums in a row each spawn fish at times set by their population; Igor starts at tank 1, walks one tank per second, and must be present at each birth. Output the time of the first birth he misses.	Hard8	GreedySimulation+2	No attempts yet	2s	1024 MB	Judgeable
About Love...Two moving line segments drift at constant velocities; find the earliest time they touch, or report -1 if they never do.	Hard8	GeometryBinary search+2	No attempts yet	2s	1024 MB	Judgeable
NumberGiven ranges [a,b] and [c,d], find the smallest integer greater than ac that is not a product u*v with u in [a,b] and v in [c,d].	Hard8	MathNumber theory+2	No attempts yet	2s	1024 MB	Judgeable