Problems

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Total results21,088 problems

CerealHard9
Greedy, Simulation +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Laser IntensificationHard9
Math, Combinatorics +2No attempts yetTime limit2sMemory limit64 MB
Judgeable
Deja VuHard9
Segment tree, Dynamic programming +2No attempts yetTime limit5sMemory limit512 MB
Judgeable
Integer Equation CheckerHard9
Brute force, Implementation +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Yet Another Problem on EmpodiaHard9
Combinatorics, Dynamic programming +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Curious Ball GameHard9
Number theory, Math +2No attempts yetTime limit0.5sMemory limit256 MB
Judgeable
Tree Average WeightHard9
Combinatorics, Tree +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
Continue the SequenceHard9
Math, Number theory +2No attempts yetTime limit4sMemory limit256 MB
Judgeable
Dirt RatioHard9
Binary search, Prefix sum +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Phone CallHard9
Graph, Minimum spanning tree +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Counting Different SummandsHard9
Combinatorics, Math +2No attempts yetTime limit2sMemory limit256 MB
Judgeable
InterpolateHard9
Math, Bit manipulation +2No attempts yetTime limit4sMemory limit256 MB
Judgeable
Kingdom ConnectivityHard9
Graph, Minimum spanning tree +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Chiaki Sequence RevisitedHard9
Math, Combinatorics +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
RMQ Similar SequenceHard9
Tree, Combinatorics +2No attempts yetTime limit2sMemory limit256 MB
Judgeable
AdditionHard9
String matching, Simulation +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
Rikka with Proper FractionsHard9
Number theory, Math +2No attempts yetTime limit10sMemory limit512 MB
Judgeable
Rikka with Tree GameHard9
Game theory, Tree +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Unseen SegmentsHard9
Geometry, Sorting +2No attempts yetTime limit2sMemory limit256 MB
Judgeable
Good GameHard9
Combinatorics, Dynamic programming +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
DoublindromesHard9
String, String matching +2No attempts yetTime limit3sMemory limit512 MB
Judgeable
TaxiHard9
Tree, Dynamic programming +2No attempts yetTime limit1.5sMemory limit256 MB
Judgeable
CandiesHard9
Number theory, Math +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Nice NumbersHard9
Combinatorics, Number theory +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
New DivideHard9
Bit manipulation, Trie +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
ConnectivityHard9
Union-find, Graph +2No attempts yetTime limit8sMemory limit256 MB
Judgeable
Array ChallengeHard9
Math, Number theory +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Master Zhu and Magic NumbersHard9
Bit manipulation, Implementation +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Master Zhu and CandiesHard9
Game theory, Math +2No attempts yetTime limit3sMemory limit512 MB
Judgeable
Master Zhu and RikkaHard9
Tree, DFS +2No attempts yetTime limit3sMemory limit512 MB
Judgeable
Master Zhu and RootHard9
Number theory, Math +2No attempts yetTime limit3sMemory limit512 MB
Judgeable
Master Zhu and the LeaperHard9
Dynamic programming, Combinatorics +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Random PointsHard9
Geometry, Combinatorics +2No attempts yetTime limit5sMemory limit512 MB
Judgeable
GCD vs LCMHard9
Number theory, Math +2No attempts yetTime limit2.5sMemory limit512 MB
Judgeable
Power of XORHard9
Bit manipulation, Math +2No attempts yetTime limit6sMemory limit512 MB
Judgeable
Performance ReviewHard9
Dynamic programming, Binary search +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
JokeHard9
String matching, Dynamic programming +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Airport Check-inHard9
Probability, Math +1No attempts yetTime limit1sMemory limit256 MB
Judgeable
EarthquakeHard9
Probability, Dynamic programming +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Window XORHard9
Math, Bit manipulation +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Flip a CoinHard9
Probability, Dynamic programming +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
K-th StringHard9
String, Combinatorics +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
Ascent Sequences Avoiding Pattern 201Hard9
Dynamic programming, Combinatorics +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Connected Spanning SubgraphHard9
Graph, Combinatorics +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Maximum FlowHard9
Graph, Shortest path +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Born SlippyHard9
Tree, Dynamic programming +2No attempts yetTime limit6sMemory limit256 MB
Judgeable
Binary Neural NetworkHard9
Implementation, Greedy +2No attempts yetTime limit2sMemory limit256 MB
Judgeable
Bitwise Range QueriesHard9
Segment tree, Bit manipulation +2No attempts yetTime limit3sMemory limit512 MB
Judgeable
Simple GraphHard9
Combinatorics, Dynamic programming +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Values on a TreeHard9
Tree, Dynamic programming +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Jong Hyok and StringHard9
String, Trie +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Less Time, More ProfitHard9
Dynamic programming, Graph +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
Pet TreeHard9
Dynamic programming, Tree +2No attempts yetTime limit8sMemory limit1024 MB
Judgeable
Matrix and QueriesHard9
Math, Matrix +2No attempts yetTime limit5sMemory limit512 MB
Judgeable
RectangleHard9
Math, Combinatorics +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
Navigation GameHard9
Greedy, Implementation +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
FenceHard9
Geometry, Binary search +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Human ErrorHard9
Game theory, Bit manipulation +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Wrong AnswerHard9
Greedy, Dynamic programming +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Sequence and Queries 39Hard9
Segment tree, Math +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
JumpHard9
Shortest path, Graph +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
ExploreHard9
Graph, Divide and conquer +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Holy cow, Vim! (Easy)Hard9
Implementation, Simulation +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Holy cow, Vim! (Hard)Hard9
Implementation, Stack +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
The Potion of Great PowerHard9
Graph, Sorting +2No attempts yetTime limit3sMemory limit256 MB
Judgeable
IslandHard9
Tree, DFS +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
AtomsHard9
Segment tree, Dynamic programming +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Fermat's Last TheoremHard9
Math, Combinatorics +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Right Expansion Of The MindHard9
String, String matching +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Oleg and Binary SequencesHard9
String matching, Dynamic programming +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Sewing GraphHard9
Geometry, Sorting +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Nowruz 1Hard9
Graph, Tree +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Nowruz 4Hard9
Tree, Greedy +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Nowruz 8Hard9
Tree, Graph +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Pebbling odometer 4Hard9
Simulation, Implementation +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Why the Cow Crossed Yonsei-roHard9
Divide and conquer, Combinatorics +2No attempts yetTime limit5sMemory limit1024 MB
Judgeable
Vista 6Hard9
Geometry, Sorting +2No attempts yetTime limit0.1sMemory limit128 MB
Judgeable
Vista 8Hard9
Geometry, Greedy +2No attempts yetTime limit0.1sMemory limit128 MB
Judgeable
Vista 9Hard9
Geometry, Greedy +2No attempts yetTime limit0.1sMemory limit128 MB
Judgeable
Stock AnalysisHard9
Prefix sum, Sorting +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
814 - 3Hard9
Geometry, Greedy +2No attempts yetTime limit4.814sMemory limit814 MB
Judgeable
HomeworkHard9
Segment tree, Math +2No attempts yetTime limit3sMemory limit1024 MB
Judgeable
Company PartiesHard9
Tree, DFS +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Random Walk on a Tree: Expected TimeHard9
Tree, Dynamic programming +2No attempts yetTime limit2.5sMemory limit512 MB
Judgeable
Minimum Spanning Tree of a Complete GraphHard9
Minimum spanning tree, Graph +2No attempts yetTime limit5sMemory limit16 MB
Judgeable
MeandianHard9
Sorting, Math +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
MVP Diamond (Hard)Hard9
Dynamic programming, Math +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Data PlacementHard9
Graph, DFS +1No attempts yetTime limit1sMemory limit512 MB
Judgeable
Dart GameHard9
Dynamic programming, Geometry +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Repairing the Bridges of Dungdung IslandHard9
Tree, Greedy +2No attempts yetTime limit3sMemory limit1024 MB
Judgeable
Cactus ShoppeHard9
Graph, DFS +2No attempts yetTime limit5sMemory limit1024 MB
Judgeable
HotelsHard9
Tree, Dynamic programming +2No attempts yetTime limit2sMemory limit256 MB
Judgeable
Rikka with StorehouseHard9
Tree, Dynamic programming +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Rikka with Composite NumberHard9
Math, Probability +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
House BuildingHard9
Greedy, Brute force +2No attempts yetTime limit4sMemory limit1024 MB
Judgeable
Bridge BuildingHard9
Tree, Shortest path +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Counting Good ArraysHard9
Combinatorics, Dynamic programming +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Instruction AnagramHard9
Combinatorics, Math +2No attempts yetTime limit4sMemory limit512 MB
Judgeable
All SubsequencesHard9
Dynamic programming, Math +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Cartesian MSTHard9
Graph, Minimum spanning tree +2No attempts yetTime limit1sMemory limit512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
CerealGiven a queue of cows each with a favorite and second-favorite cereal, report for every prefix removal how many cows still get a box.	Hard9	GreedySimulation+2	No attempts yet	1s	512 MB	Judgeable
Laser IntensificationFind probability p so that one photon entering the lower-left of a w by h grid, with nodes independently faulty with probability 1-p except n known faulty cells, yields k photons in expectation at the upper-right; print -1 if impossible.	Hard9	MathCombinatorics+2	No attempts yet	2s	64 MB	Judgeable
Deja VuMaintain an array under point updates and answer queries asking for the earliest position d that ends an increasing subsequence of length 4 starting at or after l.	Hard9	Segment treeDynamic programming+2	No attempts yet	5s	512 MB	Judgeable
Integer Equation CheckerClassify an equation string as correct, format error, math error, or a typo fixable by replacing at most two characters with a valid correct equation.	Hard9	Brute forceImplementation+2	No attempts yet	1s	512 MB	Judgeable
Yet Another Problem on EmpodiaCount, for each length i up to N, the number of equivalence classes of permutations of length i under the relation that agrees on which intervals are framed (max minus min equals length minus one), modulo a prime.	Hard9	CombinatoricsDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Curious Ball GameFor each query (N, M), find the M-th smallest bag size A such that drawing two balls gives probability exactly 1/N^2 that at least one is not red, outputting A and B mod 1e9+7.	Hard9	Number theoryMath+2	No attempts yet	0.5s	256 MB	Judgeable
Tree Average WeightGiven a degree sequence with some free entries, pick a labeled tree uniformly at random and find the integer part of its expected weight, where weight sums usz(u)+vsz(v) over edges.	Hard9	CombinatoricsTree+2	No attempts yet	1s	256 MB	Judgeable
Continue the SequenceGiven n values, extend the sequence by m terms so that it agrees with a polynomial of the smallest possible degree modulo 998244353.	Hard9	MathNumber theory+2	No attempts yet	4s	256 MB	Judgeable
Dirt RatioChoose a contiguous subarray to minimize (number of distinct values)/(subarray length); print the minimum ratio.	Hard9	Binary searchPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
Phone CallA tree of houses has m phone lines, each letting any two vertices in the union of two tree paths call at cost w. Find the maximum number of reachable houses from house 1 and the minimum cost.	Hard9	GraphMinimum spanning tree+2	No attempts yet	1s	512 MB	Judgeable
Counting Different SummandsSum f(a) over all ordered partitions of n into m positive parts, where f counts distinct part values, modulo 998244353, with n up to 1e18 and m up to 500.	Hard9	CombinatoricsMath+2	No attempts yet	2s	256 MB	Judgeable
InterpolateGiven m distinct boolean input vectors with outputs, build a Zhegalkin (XOR-of-ANDs) polynomial matching all of them using at most 9000 terms, or report that none exists.	Hard9	MathBit manipulation+2	No attempts yet	4s	256 MB	Judgeable
Kingdom ConnectivityGiven a planar straight-line graph with weighted edges, choose a minimum-weight set of edges whose removal makes both sides of every wall reachable from the exterior.	Hard9	GraphMinimum spanning tree+2	No attempts yet	2s	512 MB	Judgeable
Chiaki Sequence RevisitedSum the first n terms of the self-referential Chiaki sequence, where each term depends on earlier terms via a_{n-a_{n-1}} + a_{n-1-a_{n-2}}, modulo 1e9+7.	Hard9	MathCombinatorics+2	No attempts yet	1s	256 MB	Judgeable
RMQ Similar SequenceGiven sequence A, count the expected sum of a random real sequence B in [0,1] that has identical RMQ answers to A for every subarray, modulo 1e9+7.	Hard9	TreeCombinatorics+2	No attempts yet	2s	256 MB	Judgeable
AdditionDesign a short string-rewriting script in a custom language that reads two binary numbers joined by + and rewrites them into their binary sum.	Hard9	String matchingSimulation+2	No attempts yet	1s	256 MB	Judgeable
Rikka with Proper FractionsCount reduced proper fractions e/f with f at most n lying between two given fractions a/b and c/d, answering modulo 998244353.	Hard9	Number theoryMath+2	No attempts yet	10s	512 MB	Judgeable
Rikka with Tree GameOn a rooted tree where players alternately move a token to a child and the score is the final depth, repeatedly attach leaves and find the limit of f(k)/k, where f(k) is the fewest additions making the optimal score exactly k.	Hard9	Game theoryTree+2	No attempts yet	2s	512 MB	Judgeable
Unseen SegmentsGiven n vertical segments and queries of (west power, east power), find the total length of parts no observer sees through at most that many segments.	Hard9	GeometrySorting+2	No attempts yet	2s	256 MB	Judgeable
Good GameCount monotone lattice paths in n dimensions from the origin to a target, avoiding m forbidden points, modulo 1e9+7.	Hard9	CombinatoricsDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
DoublindromesCount distinct substrings of s that are palindromes and split into two non-empty palindromes, with length at least k.	Hard9	StringString matching+2	No attempts yet	3s	512 MB	Judgeable
TaxiSum over all ways to place M taxis and M customers on a weighted tree of the maximum-weight perfect matching cost, modulo 1e9+7.	Hard9	TreeDynamic programming+2	No attempts yet	1.5s	256 MB	Judgeable
CandiesFor each query k, count modulo 2 the pairs (child, candy kind) where buying only her favorite candy at that price leaves exactly k dollars.	Hard9	Number theoryMath+2	No attempts yet	1s	512 MB	Judgeable
Nice NumbersCount numbers in [L, R] that are pandigital (a permutation of all digits) in some base d, modulo 998244353, with L and R up to 5000-digit integers.	Hard9	CombinatoricsNumber theory+2	No attempts yet	1s	512 MB	Judgeable
New DivideFor every prefix of the array, split it into two contiguous parts maximizing the sum of the two parts' XOR values.	Hard9	Bit manipulationTrie+2	No attempts yet	2s	512 MB	Judgeable
ConnectivityAfter each of m highways is added, count ordered city pairs (a,b) such that for every one of d types, a and b are connected using only that type's edges.	Hard9	Union-findGraph+2	No attempts yet	8s	256 MB	Judgeable
Array ChallengeGiven a linear recurrence h and closed-form arrays b and a, compute floor(sqrt(a_n)) modulo 1e9+7 for n up to 1e15.	Hard9	MathNumber theory+2	No attempts yet	1s	512 MB	Judgeable
Master Zhu and Magic NumbersGiven sparse positions of ones in a triangular binary layout, simulate a bitwise dependency program to get values b_j, then answer queries asking for the popcount of ORs of selected b_j.	Hard9	Bit manipulationImplementation+2	No attempts yet	1s	512 MB	Judgeable
Master Zhu and CandiesGiven n candy heaps, players may remove any positive number from one heap or split one heap into three non-empty heaps; decide the winner under optimal play.	Hard9	Game theoryMath+2	No attempts yet	3s	512 MB	Judgeable
Master Zhu and RikkaGiven a rooted tree with values on vertices, answer queries that ask for the GCD of sums of values occurring exactly a times and exactly b times in a subtree or on a path.	Hard9	TreeDFS+2	No attempts yet	3s	512 MB	Judgeable
Master Zhu and RootFor each query (x, y), find the smallest k >= 0 with x^k congruent to y modulo some prime divisor p of n, or report -1.	Hard9	Number theoryMath+2	No attempts yet	3s	512 MB	Judgeable
Master Zhu and the LeaperCount monotone leaper paths from (1,1) to (n,m) on a huge board with at most 100 blocked cells, modulo 110119.	Hard9	Dynamic programmingCombinatorics+2	No attempts yet	1s	512 MB	Judgeable
Random PointsGiven n points in general position, output 2^n times the expected number of vertices of the convex hull of a uniformly random subset, modulo 1e9+7.	Hard9	GeometryCombinatorics+2	No attempts yet	5s	512 MB	Judgeable
GCD vs LCMFor each of q queries with n, m, a up to 1e5, sum lcm(i,j) over all i<=n, j<=m with gcd(i,j)<=a, modulo 1e9+7.	Hard9	Number theoryMath+2	No attempts yet	2.5s	512 MB	Judgeable
Power of XORGiven n integers, compute the sum over all 2^n subsets of the k-th power of the popcount of the XOR of the subset, modulo 1e9+7.	Hard9	Bit manipulationMath+2	No attempts yet	6s	512 MB	Judgeable
Performance ReviewGiven yearly rounds where the Ri worst employees are replaced by given new hires, answer Q point-update queries asking whether employee 1 survives all M years.	Hard9	Dynamic programmingBinary search+2	No attempts yet	2s	512 MB	Judgeable
JokeGiven a text and up to ten patterns with per-letter erasure costs, delete letters so that no pattern occurs, minimizing total cost.	Hard9	String matchingDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Airport Check-inEach counter has a random per-passenger time and a random remaining time for the current passenger; find the probability that the counter finishing first is also the one with the smallest per-passenger time.	Hard9	ProbabilityMath+1	No attempts yet	1s	256 MB	Judgeable
EarthquakeEach route is usable only if all its bridges survive; pick an adaptive inspection order of bridges to minimize the expected number of inspections before deciding whether any route connects the two lands.	Hard9	ProbabilityDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Window XORApply the operation that replaces each element with the XOR of K consecutive elements (cyclically) exactly T times, where T can be as large as 10^18.	Hard9	MathBit manipulation+2	No attempts yet	2s	1024 MB	Judgeable
Flip a CoinTwo players each pick a heads/tails string of length up to 20; a fair coin is flipped until one or both strings appear, and we must output the probabilities of Alice winning, Bob winning, and a tie.	Hard9	ProbabilityDynamic programming+2	No attempts yet	1s	256 MB	Judgeable
K-th StringCount permutations t of n distinct letters whose k-th smallest non-empty substring equals s, modulo 1e9+7.	Hard9	StringCombinatorics+2	No attempts yet	1s	256 MB	Judgeable
Ascent Sequences Avoiding Pattern 201Count ascent sequences of length n that avoid the pattern 201, modulo a prime p, with n up to 500.	Hard9	Dynamic programmingCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Connected Spanning SubgraphGiven a connected undirected graph, count the non-empty edge subsets whose chosen edges form a connected spanning subgraph, and print the count modulo 2.	Hard9	GraphCombinatorics+2	No attempts yet	1s	512 MB	Judgeable
Maximum FlowGiven two paths of n vertices each plus 2n+1 cross edges with huge capacities, find the max flow from (0,0) to (1,n).	Hard9	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
Born SlippyFor each vertex of a rooted tree, find the maximum weight of a walk up to an ancestor where consecutive weights combine by AND, OR, or XOR, then output a weighted sum.	Hard9	TreeDynamic programming+2	No attempts yet	6s	256 MB	Judgeable
Binary Neural NetworkGiven a truth table of an n-input Boolean function (n up to 10), build a layered sigmoid network with at most 25 layers, 10^4 neurons, and 3*10^4 edges whose single output neuron approximates f.	Hard9	ImplementationGreedy+2	No attempts yet	2s	256 MB	Judgeable
Bitwise Range QueriesMaintain an array under range AND and OR updates and answer range minimum queries, all with n up to 5*10^5 and values below 2^30.	Hard9	Segment treeBit manipulation+2	No attempts yet	3s	512 MB	Judgeable
Simple GraphSum x^k over all simple graphs on n labeled vertices, where x counts the tree components, modulo 998244353.	Hard9	CombinatoricsDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Values on a TreeFor every K from 0 to n-1, count the non-empty vertex subsets of a tree whose maximum pairwise distance equals K, modulo 998244353.	Hard9	TreeDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Jong Hyok and StringGiven n pattern strings, for each query string Q count the substrings T of the patterns with the same set of (pattern, end position) occurrence pairs as Q.	Hard9	StringTrie+2	No attempts yet	1s	1024 MB	Judgeable
Less Time, More ProfitChoose a subset of plants to build; a shop pays off only when every plant it needs is built. Minimize the maximum build time, then maximize profit within that time.	Hard9	Dynamic programmingGraph+2	No attempts yet	1s	256 MB	Judgeable
Pet TreeCount assignments of edge lengths (each within its own interval) to a tree's edges so the resulting tree diameter falls between S and E, modulo 1e9+7.	Hard9	Dynamic programmingTree+2	No attempts yet	8s	1024 MB	Judgeable
Matrix and QueriesGiven an N x N integer matrix and Q values x, output det(A - xI) mod 998244353 for each query.	Hard9	MathMatrix+2	No attempts yet	5s	512 MB	Judgeable
RectangleConstruct a 30 by 30 table of integers from 0 to 10^6 so that among all axis-aligned sub-rectangles, every integer from 1 to 50000 appears as some rectangle's sum.	Hard9	MathCombinatorics+2	No attempts yet	1s	256 MB	Judgeable
Navigation GameConstruct a 100x100 arrangement of the numbers 1 to 10000 that maximizes a navigation score, where jumps off the current row or column cost points.	Hard9	GreedyImplementation+2	No attempts yet	1s	256 MB	Judgeable
FenceGiven up to 50,000 points, find the minimum perimeter of a rectangle with arbitrary orientation that contains all of them.	Hard9	GeometryBinary search+2	No attempts yet	1s	1024 MB	Judgeable
Human ErrorGiven a grid of Justin and Donald pieces where each turn a player must capture an adjacent piece, and each player may restrict their candidate moves to a set of fixed size, compute Justin's win probability under optimal play with random move choice.	Hard9	Game theoryBit manipulation+2	No attempts yet	1s	512 MB	Judgeable
Wrong AnswerConstruct a cost matrix that makes a greedy two-character solution as far from optimal as possible, maximizing the ratio of its output to the true minimum.	Hard9	GreedyDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Sequence and Queries 39Maintain an array under range updates that add an arithmetic progression, and answer queries for the longest arithmetic-progression subarray inside a range.	Hard9	Segment treeMath+2	No attempts yet	2s	512 MB	Judgeable
JumpGiven cities at integer grid points and portals that jump from one city to any city inside an axis-aligned rectangle at a given cost, find the shortest time from city 1 to every city.	Hard9	Shortest pathGraph+2	No attempts yet	1s	512 MB	Judgeable
ExploreAn interactive graph-reconstruction task: with limited modify, query, report, and check calls, determine every edge of an unknown undirected graph.	Hard9	GraphDivide and conquer+2	No attempts yet	1s	512 MB	Judgeable
Holy cow, Vim! (Easy)Construct a stack-language program that outputs x, but outputs 2x when its lines are reversed and -x when its lines are sorted lexicographically.	Hard9	ImplementationSimulation+2	No attempts yet	1s	512 MB	Judgeable
Holy cow, Vim! (Hard)Construct a stack-program whose lines, read normally, reversed, and lexicographically sorted, compute x, x squared, and negative x respectively.	Hard9	ImplementationStack+2	No attempts yet	1s	512 MB	Judgeable
The Potion of Great PowerGiven a graph whose edges change once per day with degree at most D, answer queries online for the minimum altitude difference between a neighbor of x and a neighbor of y on a given day.	Hard9	GraphSorting+2	No attempts yet	3s	256 MB	Judgeable
IslandGiven the edge list of a tree whose N leaves are towns and whose internal nodes all have degree at least 3, count the distinct circular orderings of the leaves realizable as the outer face, and print the count as a product of prime powers.	Hard9	TreeDFS+2	No attempts yet	1s	512 MB	Judgeable
AtomsMaintain a sequence of charges under range add updates, and after restricting to a query segment, report the longest run of consecutive positions where each next charge exceeds the previous by exactly one.	Hard9	Segment treeDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Fermat's Last TheoremOrder all positive quadruples (a,b,c,n) with n>=3 by max element then lexicographically, and print the sign of a^n+b^n compared to c^n for positions l through r.	Hard9	MathCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Right Expansion Of The MindGroup n infinite strings, each formed by a finite prefix s followed by repeats of t, so that within each group every pair is mutually a subsequence of the other; minimize the number of groups.	Hard9	StringString matching+2	No attempts yet	2s	512 MB	Judgeable
Oleg and Binary SequencesCount binary sequences of length n whose Z-function matches the given entries, with -1 marking unknown values, modulo 1e9+7.	Hard9	String matchingDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Sewing GraphFind the shortest alternating front/back sequence of edges that connects all N points on both sides with no crossings on either side.	Hard9	GeometrySorting+2	No attempts yet	2s	1024 MB	Judgeable
Nowruz 1Given a grid garden with rocks and k kids, plant bushes so the remaining free cells form a tree, maximizing the number of leaves (cells with exactly one free neighbor).	Hard9	GraphTree+2	No attempts yet	1s	512 MB	Judgeable
Nowruz 4Given a grid with rocks, block more cells so the free cells form a tree, maximizing the number of free cells with exactly one free neighbor (output-only, partial scoring).	Hard9	TreeGreedy+2	No attempts yet	1s	512 MB	Judgeable
Nowruz 8Given a grid with rocks and free cells, remove free cells so the remaining free cells form a tree (unique simple path between any two), maximizing the number of degree-one cells, an output-only task scored on the submitted maps.	Hard9	TreeGraph+2	No attempts yet	1s	512 MB	Judgeable
Pebbling odometer 4Write a program in the odometer's own command language (move, turn, get/put, and label jumps) that gathers every pebble on the 256x256 grid into cell (0,0), using at most 200 commands.	Hard9	SimulationImplementation+2	No attempts yet	1s	512 MB	Judgeable
Why the Cow Crossed Yonsei-roGiven two permutations of 1..N, sum over all cyclic rotations of each side the number of crossing pairs (inversions) between the two orders, modulo 1,000,000,009.	Hard9	Divide and conquerCombinatorics+2	No attempts yet	5s	1024 MB	Judgeable
Vista 6Given up to a million distinct points in the plane, output a cyclic order visiting all of them that is short enough under the Euclidean metric.	Hard9	GeometrySorting+2	No attempts yet	0.1s	128 MB	Judgeable
Vista 8Given up to a million distinct points in the plane, output a cyclic tour that visits every point and returns to the start, under the Euclidean metric.	Hard9	GeometryGreedy+2	No attempts yet	0.1s	128 MB	Judgeable
Vista 9Given up to a million points in the plane, output a cyclic tour that visits each point once and returns to the start.	Hard9	GeometryGreedy+2	No attempts yet	0.1s	128 MB	Judgeable
Stock AnalysisFor each of up to 200,000 queries (S, E, U), report the largest subarray sum within a[S..E] that does not exceed U, or NONE if none exists.	Hard9	Prefix sumSorting+2	No attempts yet	2s	512 MB	Judgeable
814 - 3Partition 8000 random points among 140 salesmen and give each a closed tour so the longest tour is as short as possible.	Hard9	GeometryGreedy+2	No attempts yet	4.814s	814 MB	Judgeable
HomeworkEach child builds an expression from range-assigned operators and integers; output the sum of all expression values modulo 1e9+7 under PEMDAS.	Hard9	Segment treeMath+2	No attempts yet	3s	1024 MB	Judgeable
Company PartiesGiven a rooted company tree with nondecreasing ages toward the root, answer M queries each asking which employees lie in the maximal connected subtree inside an age interval that contains the host.	Hard9	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
Random Walk on a Tree: Expected TimeGiven a tree, answer queries giving the expected hitting time of a random walk from one vertex to another, modulo 1e9+7.	Hard9	TreeDynamic programming+2	No attempts yet	2.5s	512 MB	Judgeable
Minimum Spanning Tree of a Complete GraphGiven a complete graph on N vertices where each edge weight is derived from vertex values by an arithmetic and XOR formula, find the total weight of the minimum spanning tree.	Hard9	Minimum spanning treeGraph+2	No attempts yet	5s	16 MB	Judgeable
MeandianUsing at most 1000 queries to a library that returns the mean of the two middle salaries among any four distinct employees, recover every salary that is uniquely determined by the answers.	Hard9	SortingMath+2	No attempts yet	2s	512 MB	Judgeable
MVP Diamond (Hard)Given N monthly MVP tiers and four thresholds, find the maximum total spending that could produce that tier sequence, with each month capped at d and spend in units of 10,000.	Hard9	Dynamic programmingMath+2	No attempts yet	1s	512 MB	Judgeable
Data PlacementGiven a connected undirected graph, find the minimum size of a vertex set A such that for every vertex outside A and every single removed edge, some vertex of A still reaches it, and count the minimum sets modulo 1e9+7.	Hard9	GraphDFS+1	No attempts yet	1s	512 MB	Judgeable
Dart GameGiven K rounds of weighted Seunggyu darts and movable Uiseok darts, compute the original score and the max and min achievable scores after relocating at most L Uiseok darts, all modulo 1e9+7.	Hard9	Dynamic programmingGeometry+2	No attempts yet	2s	512 MB	Judgeable
Repairing the Bridges of Dungdung IslandOn a tree where every edge costs 2, answer queries giving a capital u and a count a: choose a edges to make cost 1 so the sum of distances from all nodes to u is minimized.	Hard9	TreeGreedy+2	No attempts yet	3s	1024 MB	Judgeable
Cactus ShoppeGiven a cactus whose vertices carry values, and divisibility queries, count the connected components left after deleting every vertex not divisible by the query.	Hard9	GraphDFS+2	No attempts yet	5s	1024 MB	Judgeable
HotelsGiven a weighted tree and three independent uniform choices of vertices from three candidate sets, find the expected total distance from the three chosen vertices to their median (the vertex minimizing the sum of distances).	Hard9	TreeDynamic programming+2	No attempts yet	2s	256 MB	Judgeable
Rikka with StorehouseOn a complete binary tree of 2^n-1 nodes, the last half of node values are given and updated; minimize the sum of squared edge differences over the free nodes after each update, modulo 998244353.	Hard9	TreeDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Rikka with Composite NumberGiven a set of digits, find the expected number of random digits drawn before the growing decimal number first becomes composite, modulo 998244353.	Hard9	MathProbability+2	No attempts yet	1s	512 MB	Judgeable
House BuildingPlace K houses on an N by M grid so that the total happiness, each house's value times its Manhattan distance to the nearest other house, is as large as possible.	Hard9	GreedyBrute force+2	No attempts yet	4s	1024 MB	Judgeable
Bridge BuildingGiven a weighted tree and up to two extra edges, answer queries for the shortest path between pairs of vertices after adding those edges.	Hard9	TreeShortest path+2	No attempts yet	2s	1024 MB	Judgeable
Counting Good ArraysCount permutations of 1..n with one value duplicated, whose inversion-like score falls in [a,b], modulo 1e9+7.	Hard9	CombinatoricsDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Instruction AnagramCount strings S consistent with observations, given that P is an anagram of S and the robot's positions at certain times are known.	Hard9	CombinatoricsMath+2	No attempts yet	4s	512 MB	Judgeable
All SubsequencesSum the absolute product of consecutive differences over every subsequence of A, modulo 998244353.	Hard9	Dynamic programmingMath+2	No attempts yet	1s	512 MB	Judgeable
Cartesian MSTGiven two connected weighted graphs G and H, compute the total weight of the minimum spanning tree of their Cartesian product G square H.	Hard9	GraphMinimum spanning tree+2	No attempts yet	1s	512 MB	Judgeable