Problems

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Total results21,682 problems

XEN 3166Hard8
Greedy, String +1No attempts yetTime limit2sMemory limit512 MB
Judgeable
PermutationHard8
Math, Combinatorics +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Sacred ScarecrowsHard8
Dynamic programming, Bit manipulation +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
CitationsHard8
Tree, Greedy +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Love PolygonHard8
Graph, Greedy +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
PathsHard8
Graph, DFS +2No attempts yetTime limit3sMemory limit1024 MB
Judgeable
SubwayHard8
Graph, Tree +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Nordic CampingHard8
Dynamic programming, Binary search +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Mysterious ArrayHard8
Combinatorics, Sorting +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Pineapple FarmingHard8
Union-find, BFS +2No attempts yetTime limit2sMemory limit256 MB
Judgeable
Pineapple PizzaHard8
Geometry, Sorting +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
Turf WarsHard8
Geometry, Brute force +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Longest Common Palindromic SubstringHard8
String, String matching +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Split and MergeHard8
Dynamic programming, Combinatorics +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Full HouseHard8
Combinatorics, Greedy +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Matrix MultiplicationHard8
Greedy, Sorting +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
RooksHard8
Graph, Greedy +2No attempts yetTime limit0.4sMemory limit1024 MB
Judgeable
A Simple ProblemHard8
Number theory, Math +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Harmonious MatrixHard8
Sorting, Hash map +2No attempts yetTime limit5sMemory limit768 MB
Judgeable
Teleport PadsHard8
Graph, BFS +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Magic NecklaceHard8
Math, Number theory +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Kakao MoneyHard8
Math, Number theory +2No attempts yetTime limit5sMemory limit256 MB
Judgeable
Magnet ToyHard8
Graph, Implementation +2No attempts yetTime limit1.5sMemory limit256 MB
Judgeable
ShootingsHard8
Geometry, Sorting +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
POPAHard8
Divide and conquer, Tree +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Maximum Strategic SavingsHard8
Minimum spanning tree, Graph +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Global warmingHard8
Dynamic programming, Binary search +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
LotteryHard8
String matching, Hash map +2No attempts yetTime limit2sMemory limit32 MB
Judgeable
ToysHard8
Number theory, Combinatorics +2No attempts yetTime limit4sMemory limit512 MB
Judgeable
TrianglesHard8
Geometry, Divide and conquer +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Playoff by all the teamsHard8
Brute force, Backtracking +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Flashing FluorescentsHard8
BFS, Bit manipulation +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Zoning HousesHard8
Segment tree, Divide and conquer +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Word ClockHard8
Backtracking, Implementation +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Battle RoyaleHard8
Geometry, Math +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Hyper IlluminatiHard8
Math, Number theory +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Монгол ардын үлгэрHard8
Dynamic programming, Sorting +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Cruise QuailHard8
Graph, Union-find +2No attempts yetTime limit3sMemory limit512 MB
Judgeable
Willy Feels GuiltyHard8
String matching, Greedy +1No attempts yetTime limit2sMemory limit512 MB
Judgeable
Amateur Radio NetworkHard8
Geometry, Binary search +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Grumpy Groundhogs in GridlandHard8
Graph, BFS +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Fair ShareHard8
Geometry, Sorting +2No attempts yetTime limit5sMemory limit512 MB
Judgeable
Grievous Loss of DataHard8
Graph, Intervals +2No attempts yetTime limit6sMemory limit512 MB
Judgeable
Hiding MerlinHard8
String matching, Dynamic programming +2No attempts yetTime limit4sMemory limit512 MB
Judgeable
Injecting DNAHard8
String, Sorting +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Judge's MistakeHard8
Greedy, Sorting +1No attempts yetTime limit4sMemory limit512 MB
Judgeable
I'm a FanHard8
Geometry, Math +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
CherrypickHard8
Matrix, Binary search +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Office RelocationHard8
Tree, Dynamic programming +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Club Room ExpansionHard8
Dynamic programming, Backtracking +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Ttururu TturuHard8
DFS, Brute force +2No attempts yetTime limit0.5sMemory limit512 MB
Judgeable
Number Theory and ApplicationsHard8
Number theory, Math +2No attempts yetTime limit0.2sMemory limit16 MB
Judgeable
Number Theory and Applications: RecitationHard8
Number theory, Math +2No attempts yetTime limit4sMemory limit512 MB
Judgeable
Racial DiscriminationHard8
Bit manipulation, Brute force +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Peace SignHard8
Geometry, Hash map +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Binary Tree and SequenceHard8
String matching, Hash map +2No attempts yetTime limit3sMemory limit256 MB
Judgeable
Liar GameHard8
Combinatorics, Dynamic programming +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Coloring RoadsHard8
Tree, Segment tree +2No attempts yetTime limit4sMemory limit1024 MB
Judgeable
Fake Plastic TreesHard8
Tree, Math +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
UtilitarianismHard8
Tree, Dynamic programming +2No attempts yetTime limit5sMemory limit1024 MB
Judgeable
Balcony RepairsHard8
Dynamic programming, Combinatorics +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Finding Tricky NumbersHard8
Dynamic programming, Binary search +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
LazinessHard8
Math, Greedy +1No attempts yetTime limit1sMemory limit512 MB
Judgeable
Baek ChaewonHard8
Graph, Shortest path +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
ClustersHard8
Dynamic programming, Prefix sum +2No attempts yetTime limit3sMemory limit1024 MB
Judgeable
We Live Forgetting the TruthHard8
Graph, Combinatorics +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Rangers in the BusHard8
Simulation, Greedy +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Memory ManagerHard8
Greedy, Dynamic programming +2No attempts yetTime limit3sMemory limit512 MB
Judgeable
Array StudyHard8
Prefix sum, Divide and conquer +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Small NumbersHard8
Number theory, Math +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Folding the FigureHard8
Implementation, Geometry +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Similar WordsHard8
Trie, Tree +2No attempts yetTime limit4sMemory limit512 MB
Judgeable
Eleventh BirthdayHard8
Dynamic programming, Combinatorics +1No attempts yetTime limit4sMemory limit512 MB
Judgeable
Masha and CactusHard8
Tree, Dynamic programming +2No attempts yetTime limit4sMemory limit512 MB
Judgeable
PanokseonHard8
Greedy, Binary search +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
ParcelHard8
Two pointers, Hash map +1No attempts yetTime limit1sMemory limit512 MB
Judgeable
Suffix-FreenessHard8
String matching, Graph +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Eating Everything EfficientlyHard8
Dynamic programming, Graph +1No attempts yetTime limit3sMemory limit512 MB
Judgeable
Isomorphic InversionHard8
Greedy, String matching +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
KALLAX ConstructionHard8
Dynamic programming, Greedy +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Harry the HamsterHard8
Game theory, Dynamic programming +2No attempts yetTime limit3sMemory limit512 MB
Judgeable
Kingpin EscapeHard8
Tree, Greedy +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Intergalactic BiddingHard8
Greedy, Sorting +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
King's ColorsHard8
Tree, Dynamic programming +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Broken WatchHard8
Math, Combinatorics +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
TreeHard8
Tree, Binary search +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
InversionHard8
Graph, Brute force +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
HorsemeetHard8
Probability, Graph +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
LightingHard8
Dynamic programming, Bit manipulation +1No attempts yetTime limit2sMemory limit512 MB
Judgeable
Locker RoomHard8
String, Greedy +2No attempts yetTime limit6sMemory limit512 MB
Judgeable
Numbers GeneratorHard8
String matching, Hash map +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
PlateHard8
Math, Simulation +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Tree in TreeHard8
Tree, DFS +2No attempts yetTime limit6sMemory limit512 MB
Judgeable
Cosmetic SurveyHard8
Graph, Shortest path +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
ParenthesesHard8
Stack, Recursion +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Secret CodeHard8
Combinatorics, Geometry +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
TV Show GameHard8
Dynamic programming, Brute force +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Chemical tableHard8
Union-find, Graph +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Prime Tree - 5Hard8
Greedy, Number theory +2No attempts yetTime limit10sMemory limit512 MB
Judgeable
Prime Tree - 8Hard8
Tree, Greedy +2No attempts yetTime limit10sMemory limit512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
XEN 3166Assign each country a length-K subsequence starting with its first letter so that code order matches name lexicographic order, or report impossible.	Hard8	GreedyString+1	No attempts yet	2s	512 MB	Judgeable
PermutationGiven a permutation P and queries K, find the exponent T such that P^T is the K-th smallest among P^1 through P^(M-1) in lexicographic order.	Hard8	MathCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Sacred ScarecrowsCount subsets of empty cells in an R x C grid, modulo 1e9+7, such that every row has a scarecrow and every pair of consecutive columns has one.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
CitationsOrder the reading of a citation tree rooted at book 1 so that the sum of all book return times is minimized.	Hard8	TreeGreedy+2	No attempts yet	1s	1024 MB	Judgeable
Love PolygonEach of N people loves exactly one person; rewrite the minimum number of love targets so that everyone ends up in a mutual pair.	Hard8	GraphGreedy+2	No attempts yet	2s	1024 MB	Judgeable
PathsCount simple paths in a vertex-colored graph where every vertex on the path has a distinct color, counting both directions separately.	Hard8	GraphDFS+2	No attempts yet	3s	1024 MB	Judgeable
SubwayGiven two spanning trees on the same N stations, output a shortest sequence of weekend swaps, each removing one tree edge and adding another, so every intermediate graph stays a spanning tree and the target tree is reached.	Hard8	GraphTree+2	No attempts yet	2s	1024 MB	Judgeable
Nordic CampingGiven a grid with rocky cells blocked, answer queries each asking for the area of the largest all-usable square subgrid that contains a specified water source cell.	Hard8	Dynamic programmingBinary search+2	No attempts yet	2s	512 MB	Judgeable
Mysterious ArrayCount permutations of 1..N consistent with Q range-minimum constraints, modulo 1e9+7, with contradictions giving 0.	Hard8	CombinatoricsSorting+2	No attempts yet	2s	512 MB	Judgeable
Pineapple FarmingOn a grid of heights with all outside cells treated as height 0, find the largest connected set of cells that forms a puddle bounded by strictly taller neighbors for some threshold h.	Hard8	Union-findBFS+2	No attempts yet	2s	256 MB	Judgeable
Pineapple PizzaGiven n points and a center Q, decide whether k rays from Q can split the plane so every sector holds exactly n/k points, with no point on a ray.	Hard8	GeometrySorting+2	No attempts yet	1s	256 MB	Judgeable
Turf WarsEach gang owns disjoint axis-aligned rectangles; pick exactly one rectangle to drop per gang so that no two kept rectangles from different gangs overlap, and report whether this is possible.	Hard8	GeometryBrute force+2	No attempts yet	2s	512 MB	Judgeable
Longest Common Palindromic SubstringGiven up to 50 strings with total length 1,000,000, find the length of the longest palindrome that occurs as a substring in every one of them.	Hard8	StringString matching+2	No attempts yet	1s	512 MB	Judgeable
Split and MergeGiven two tilings of a 1xL board by 1x1 and 1x2 pieces, find the minimum number of split/merge operations to transform one into the other and count the ways.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	1s	512 MB	Judgeable
Full HouseKnowing only how many cards were removed from a 52-card deck, find the minimum and maximum number of disjoint full houses (3 of one rank plus 2 of another) that can be formed from the remaining cards.	Hard8	CombinatoricsGreedy+2	No attempts yet	2s	512 MB	Judgeable
Matrix MultiplicationFor each prefix of n matrices, decide whether some multiplication order is valid, and if so report the largest possible area of the final product.	Hard8	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
RooksPlace the maximum number of non-attacking rooks on an N by N board where obstacles block lines of sight along ranks and files, and output one optimal placement.	Hard8	GraphGreedy+2	No attempts yet	0.4s	1024 MB	Judgeable
A Simple ProblemFind positive integers B_i so that the product of (A_i + B_i)/B_i equals 1 + (2^m - 1)/n, or report that none exist.	Hard8	Number theoryMath+2	No attempts yet	1s	512 MB	Judgeable
Harmonious MatrixGiven a 2xN or 3xN matrix of distinct integers, find the largest subset of columns whose orderings within each row are identical, and report its column count.	Hard8	SortingHash map+2	No attempts yet	5s	768 MB	Judgeable
Teleport PadsEach pad cycles through a fixed list of zones with its own period; find the earliest time Hyeonuk, starting on pad 1 at coordinate 0, can reach the exit zone by riding and switching pads.	Hard8	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
Magic NecklaceFor each of the N cut positions on a circular array, fuse contiguous segments into one bead equal to their gcd so that every resulting bead is 1, and report the maximum bead count.	Hard8	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Kakao MoneyGiven a log of deposits and withdrawals with resulting balances, find a minimum charge unit M that is consistent with every withdrawal, or report that none exists.	Hard8	MathNumber theory+2	No attempts yet	5s	256 MB	Judgeable
Magnet ToyGiven a simple graph, decide whether its vertices can be removed one by one so that each removed vertex's remaining neighbors form a clique, and output the order if possible.	Hard8	GraphImplementation+2	No attempts yet	1.5s	256 MB	Judgeable
ShootingsGiven non-overlapping axis-aligned rectangles and shots that are vertical or 45-degree half-lines, compute for each shot the squared total length of its intersection with all rectangles.	Hard8	GeometrySorting+2	No attempts yet	1s	512 MB	Judgeable
POPABuild a binary tree on indices with inorder order 0..N-1 and parent weights dividing child weights, using at most Q gcd-equality queries on hidden subarrays.	Hard8	Divide and conquerTree+2	No attempts yet	1s	512 MB	Judgeable
Maximum Strategic SavingsGiven N planets each with M cities and edge sets shared across copies, find the maximum energy saved by keeping a spanning connected subgraph of the whole galaxy.	Hard8	Minimum spanning treeGraph+2	No attempts yet	2s	512 MB	Judgeable
Global warmingChoose one contiguous interval and a shift d with \|d\| <= x, then find the maximum possible length of a strictly increasing subsequence of the modified sequence.	Hard8	Dynamic programmingBinary search+2	No attempts yet	2s	512 MB	Judgeable
LotteryFor each of n-l+1 length-l windows and each query threshold k, count how many other windows differ from it in at most k positions.	Hard8	String matchingHash map+2	No attempts yet	2s	32 MB	Judgeable
ToysFor a given n, find every total toy count m whose partitions into type-quantities number exactly n.	Hard8	Number theoryCombinatorics+2	No attempts yet	4s	512 MB	Judgeable
TrianglesFind the number of vertices of the convex hull of n points using only clockwise or counterclockwise orientation queries on triples, with a query budget.	Hard8	GeometryDivide and conquer+2	No attempts yet	2s	512 MB	Judgeable
Playoff by all the teamsCount the ways to fill in the unplayed matches of a round-robin tournament so that every team ends with the same number of wins.	Hard8	Brute forceBacktracking+2	No attempts yet	2s	512 MB	Judgeable
Flashing FluorescentsGiven up to 16 initial light states, find the earliest time at which all lights can be simultaneously on, where each button press sends a delayed toggle wave down the line and overlapping waves cancel.	Hard8	BFSBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
Zoning HousesFor each query range of houses, find the side length of the smallest axis-aligned square covering all points in the range, with the option to drop one point.	Hard8	Segment treeDivide and conquer+2	No attempts yet	2s	512 MB	Judgeable
Word ClockPlace n distinct words left to right on an h by w grid where words may share letters, or report that no placement exists.	Hard8	BacktrackingImplementation+2	No attempts yet	2s	512 MB	Judgeable
Battle RoyaleFind the shortest path between two points inside a circle while staying outside an inner red circle, touching boundaries only.	Hard8	GeometryMath+2	No attempts yet	2s	512 MB	Judgeable
Hyper IlluminatiGiven m up to 10^16, find n >= 3 and s >= 1 such that the block count of an n-dimensional hyper-step pyramid with s steps equals m, or report impossible.	Hard8	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Монгол ардын үлгэрChoose a subset whose size is at most the total weight of the remaining stones, maximizing the value of that chosen subset.	Hard8	Dynamic programmingSorting+2	No attempts yet	2s	512 MB	Judgeable
Cruise QuailFind the cheapest edge subset hitting every pair of edge-disjoint simple paths, equivalently place cameras inside each 2-edge-connected block.	Hard8	GraphUnion-find+2	No attempts yet	3s	512 MB	Judgeable
Willy Feels GuiltyBuy, throw, or swap products so the delivered sequence realizes a fixed menu at minimum total cost.	Hard8	String matchingGreedy+1	No attempts yet	2s	512 MB	Judgeable
Amateur Radio NetworkSplit at least 4 points into two groups of size at least 2 minimizing the largest same-group pairwise distance, and output that diameter rounded up to 0.01.	Hard8	GeometryBinary search+2	No attempts yet	2s	512 MB	Judgeable
Grumpy Groundhogs in GridlandGiven N nested or disjoint burrow pairs on a line at depth 0, find the minimum maximum digging depth connecting only matched pairs, or report IMPOSSIBLE.	Hard8	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
Fair ShareGiven n weighted points around the origin, choose a line through the origin that splits them into two half-planes, minimizing the absolute difference of the two half-plane weight sums.	Hard8	GeometrySorting+2	No attempts yet	5s	512 MB	Judgeable
Grievous Loss of DataGiven the clash graph of N interval lectures, find the minimum number of halls, which equals the chromatic number guaranteed realizable by intervals.	Hard8	GraphIntervals+2	No attempts yet	6s	512 MB	Judgeable
Hiding MerlinDecompose a digit string into concatenated perfect squares, each at most 10 digits and starting with 1 to 9, and report the smallest possible total sum.	Hard8	String matchingDynamic programming+2	No attempts yet	4s	512 MB	Judgeable
Injecting DNAFor every suffix of a string, compute its toxicity from the number of out-of-order suffix pairs, then output the length of the suffix with the largest effectiveness.	Hard8	StringSorting+2	No attempts yet	2s	512 MB	Judgeable
Judge's MistakeGroup sorted road triples to maximize disjoint pairs of equal (w, endpoint multiset) triples for the cheapest surviving-road sum.	Hard8	GreedySorting+1	No attempts yet	4s	512 MB	Judgeable
I'm a FanFind the smallest CCW rotation angle whose swept orbit of a star-shaped polygon around the origin is a full disk.	Hard8	GeometryMath+2	No attempts yet	2s	512 MB	Judgeable
CherrypickFor each cell, find the axis-aligned square containing it that maximizes the minimum cherry sweetness minus the square of its side length.	Hard8	MatrixBinary search+2	No attempts yet	2s	512 MB	Judgeable
Office RelocationGiven a weighted tree with marked query and leaf-coloured vertices, compute for every marked vertex the sum of squared weighted distances to coloured leaves (mod a prime).	Hard8	TreeDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Club Room ExpansionGiven each cell's count of walled directions (0 to 4), decide whether the grid can be fully partitioned into connected rooms of one to three cells fitting that wall count.	Hard8	Dynamic programmingBacktracking+2	No attempts yet	1s	512 MB	Judgeable
Ttururu TturuCount self-avoiding walks of length 10 on an R x C grid whose cell contents read exactly "ttururu tturu" (the 5-letter chorus "뚜루루뚜루" written row-wise twice).	Hard8	DFSBrute force+2	No attempts yet	0.5s	512 MB	Judgeable
Number Theory and ApplicationsGiven two Gaussian integers up to 10^9 in each coordinate, output every greatest common divisor in lexicographic order.	Hard8	Number theoryMath+2	No attempts yet	0.2s	16 MB	Judgeable
Number Theory and Applications: RecitationGiven n up to 1e9 and v up to 100, compute the sum over i=1..n and u=1..v of Jordan's totient function modulo 1e9+7.	Hard8	Number theoryMath+2	No attempts yet	4s	512 MB	Judgeable
Racial DiscriminationWith up to 10 categories and 200 people, each with a selected flag, choose at most c categories and a rule on their bit patterns that misclassifies as few people as possible, and output that minimum.	Hard8	Bit manipulationBrute force+2	No attempts yet	2s	512 MB	Judgeable
Peace SignFind the similarity transform (translation, rotation, uniform scale) of the first segment set that matches the most segments of the second set, counting exact matches.	Hard8	GeometryHash map+2	No attempts yet	2s	512 MB	Judgeable
Binary Tree and SequenceFind the smallest tree depth where one concatenated leaf sequence occurs at least K times under a periodic leaf pattern.	Hard8	String matchingHash map+2	No attempts yet	3s	256 MB	Judgeable
Liar GameFor N cards (one Joker) and R rounds, compute the probability of scoring K points, times (2*N)^R, modulo 1000003.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Coloring RoadsColor every edge on a root path with a given color and then count colors used on exactly m edges, answering Q updates online.	Hard8	TreeSegment tree+2	No attempts yet	4s	1024 MB	Judgeable
Fake Plastic TreesBuild at most 125 balanced binary trees, reusing earlier trees as subtrees, so that one of them has exactly N nodes.	Hard8	TreeMath+2	No attempts yet	1s	1024 MB	Judgeable
UtilitarianismPick k tree edges with no shared endpoints to maximize total value; the answer is a matching-style DP with a slope-trick lambda search over edge weights.	Hard8	TreeDynamic programming+2	No attempts yet	5s	1024 MB	Judgeable
Balcony RepairsGiven a huge R by C grid with at most 1000 blocked cells, place horizontal dominoes on free cells to maximize the count, then report that maximum and the number of ways modulo 1e9+7.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Finding Tricky NumbersGiven A and K up to 10^18, find the K-th positive integer whose adjacent digits differ by at least A, and print it modulo 10^9+7.	Hard8	Dynamic programmingBinary search+2	No attempts yet	1s	512 MB	Judgeable
LazinessCut a bar of total length into given pieces with cut cost xy and minimize total cost; the cost is fixed at (sum of squares differences)/2, so just read the lengths.	Hard8	MathGreedy+1	No attempts yet	1s	512 MB	Judgeable
Baek ChaewonFind the homes where Baek Chaewon can always escape K equal-speed followers from node 1 along a shortest path in an undirected weighted graph.	Hard8	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
ClustersPartition companies 1..N into contiguous clusters, each led by its first or last company whose limit L_i caps the size, minimizing the sum of C_i*S + T_i over leaders.	Hard8	Dynamic programmingPrefix sum+2	No attempts yet	3s	1024 MB	Judgeable
We Live Forgetting the TruthGiven a fixed n-vertex graph, find min and max pairs revealed in a random pair order before an online decision rule can prove it connected or not.	Hard8	GraphCombinatorics+2	No attempts yet	1s	1024 MB	Judgeable
Rangers in the BusGiven each passenger's entry order and taken seat, determine which passengers could have been each of five rangers whose seat choice follows a fixed rule or a free choice.	Hard8	SimulationGreedy+2	No attempts yet	2s	512 MB	Judgeable
Memory ManagerMove k pointers among blocks to cover each query's set, paying s_i unless already covered; minimize total cost, with initial position free.	Hard8	GreedyDynamic programming+2	No attempts yet	3s	512 MB	Judgeable
Array StudyFor each of q subarray queries on an array of 1 and -1, find the longest zero-sum subarray inside it, and print the sum of these lengths.	Hard8	Prefix sumDivide and conquer+2	No attempts yet	2s	512 MB	Judgeable
Small NumbersGiven positive integers a and b, reduce their sum using common-divisor divisions and factor moves between them. Report the minimum sum and one minimizing pair.	Hard8	Number theoryMath+2	No attempts yet	2s	512 MB	Judgeable
Folding the FigureGiven a connected polyomino of n cells that results from folding a k-cell polyomino along one grid line, reconstruct any valid original k-cell figure and the fold line.	Hard8	ImplementationGeometry+2	No attempts yet	2s	512 MB	Judgeable
Similar WordsGiven a set of distinct words, choose as many prefixes as possible so that no two chosen words differ by deleting one leading letter.	Hard8	TrieTree+2	No attempts yet	4s	512 MB	Judgeable
Eleventh BirthdayCount permutations of cards whose concatenation is divisible by 11, where cards count as distinct and equal numbers still give separate permutations.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	4s	512 MB	Judgeable
Masha and CactusChoose a maximum-weight subset of extra edges whose tree paths keep each vertex in at most one cycle, by a subtree DP with lazy updates on the path to the root.	Hard8	TreeDynamic programming+2	No attempts yet	4s	512 MB	Judgeable
PanokseonSplit a sequence of n positive weights into groups with sum at most W to minimize the maximum of (W minus group sum) squared.	Hard8	GreedyBinary search+2	No attempts yet	1s	512 MB	Judgeable
ParcelGiven n distinct integers and target w, decide whether four of them sum exactly to w.	Hard8	Two pointersHash map+1	No attempts yet	1s	512 MB	Judgeable
Suffix-FreenessGiven a DFA with n at most 2000 states and f final states, decide whether some accepted string is a proper suffix of another accepted string, and answer 1 or 0.	Hard8	String matchingGraph+2	No attempts yet	2s	512 MB	Judgeable
Eating Everything EfficientlyFollow a directed path from stall 0 and choose stalls to eat with halves 1, 1/2, 1/4, ..., maximizing the weighted satisfaction.	Hard8	Dynamic programmingGraph+1	No attempts yet	3s	512 MB	Judgeable
Isomorphic InversionSplit a digit string into the largest number of contiguous pieces whose sequence of pieces reads the same forward and backward.	Hard8	GreedyString matching+2	No attempts yet	1s	512 MB	Judgeable
KALLAX ConstructionGiven a chain of companies that each combine previous pack sizes to reach target sizes, find the smallest advertised pack guaranteeing at least B bolts.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	512 MB	Judgeable
Harry the HamsterOn a directed weighted graph, Max and Min alternately choose the outgoing edge, Max moving first; compute the total travel time from s to t under optimal play.	Hard8	Game theoryDynamic programming+2	No attempts yet	3s	512 MB	Judgeable
Kingpin EscapeAdd as few edges as possible to a tree with root h so that destroying any one edge still leaves every node connected to h; output the new edges.	Hard8	TreeGreedy+2	No attempts yet	2s	512 MB	Judgeable
Intergalactic BiddingGiven up to 1000 bidders with huge distinct bids and a huge target s, find every bidder contained in a subset whose sum is exactly s.	Hard8	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
King's ColorsCount proper colorings of a rooted tree with n nodes using exactly k labeled colors, modulo 1000000007, where every color must appear at least once.	Hard8	TreeDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Broken WatchPlace three hands at distinct markings, form a triangle from their tips, and count the center-containing triangles modulo 2^64.	Hard8	MathCombinatorics+2	No attempts yet	1s	512 MB	Judgeable
TreeChoose exactly m black vertices on a tree so that the maximum distance between any two chosen vertices is as small as possible.	Hard8	TreeBinary search+2	No attempts yet	1s	512 MB	Judgeable
InversionGiven the inversion graph of a permutation on at most 100 vertices, count its independent sets that also dominate every vertex outside. The answer fits in 10^18.	Hard8	GraphBrute force+2	No attempts yet	1s	512 MB	Judgeable
HorsemeetTwo knights move randomly to legal knight-move squares on an 8x8 board; find which knight has the higher probability of being the first to land on the other's square.	Hard8	ProbabilityGraph+2	No attempts yet	2s	512 MB	Judgeable
LightingCount N-bit b such that standard addition a+b yields exactly K set bits, using digit DP over the carries of the binary addition.	Hard8	Dynamic programmingBit manipulation+1	No attempts yet	2s	512 MB	Judgeable
Locker RoomPick length-K substrings from a cyclic string covering every position and minimize their lexicographic maximum.	Hard8	StringGreedy+2	No attempts yet	6s	512 MB	Judgeable
Numbers GeneratorGiven up to ten H/T patterns of the same length, compute the expected number of fair coin flips until one pattern first appears contiguous.	Hard8	String matchingHash map+2	No attempts yet	2s	512 MB	Judgeable
PlateAssign labels to odd lattice points on a quadrant-by-quadrant recursive spiral, then sum labels of points on x + y = k.	Hard8	MathSimulation+2	No attempts yet	1s	512 MB	Judgeable
Tree in TreeFor each vertex subset, count the edges in its minimal connecting subtree using Euler tour order and LCA checks.	Hard8	TreeDFS+2	No attempts yet	6s	512 MB	Judgeable
Cosmetic SurveyGiven n evaluators' ranked preference lists over m cosmetics, build the pairwise strict-preference counts and find every cosmetic X with S(X,Y) >= S(Y,X) for all Y, where S is the widest-path bottleneck strength.	Hard8	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
ParenthesesClassify a C arithmetic expression as error, proper, or improper depending on validity and the minimality of its parentheses.	Hard8	StackRecursion+2	No attempts yet	1s	512 MB	Judgeable
Secret CodeFind the probability of three uniformly timed agents meeting pairwise through their fixed waiting windows, then print the scenario indices sorted by that probability.	Hard8	CombinatoricsGeometry+2	No attempts yet	1s	512 MB	Judgeable
TV Show GameAssign each of k lamps red or blue so that every one of n triples of color guesses has at least two matches, or report impossible.	Hard8	Dynamic programmingBrute force+2	No attempts yet	1s	512 MB	Judgeable
Chemical tableGiven some cells of an n by m grid, fill the rest by purchasing cells and closing 2x2 rectangles; find the minimum number of purchases.	Hard8	Union-findGraph+2	No attempts yet	1s	512 MB	Judgeable
Prime Tree - 5Assign labels 1 to n to a tree's vertices so that as few edges as possible join two labels sharing a common divisor.	Hard8	GreedyNumber theory+2	No attempts yet	10s	512 MB	Judgeable
Prime Tree - 8Relabel the vertices of a tree with 1..n to minimize edges whose endpoints share a common divisor greater than 1. Output only, no fixed answer.	Hard8	TreeGreedy+2	No attempts yet	10s	512 MB	Judgeable