Problems

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Total results21,417 problems

Dynamic Short PathHard8
Shortest path, Graph +1No attempts yetTime limit7.5sMemory limit1024 MB
Judgeable
Equivalent PipelinesHard8
Union-find, Sorting +2No attempts yetTime limit3sMemory limit1024 MB
Judgeable
Flowerbed RedecorationHard8
Simulation, Matrix +1No attempts yetTime limit3sMemory limit1024 MB
Judgeable
Organizing BeadsHard8
Prefix sum, Sorting +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Periodic RulerHard8
Math, Number theory +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Three CompetitionsHard8
Graph, Sorting +2No attempts yetTime limit5sMemory limit1024 MB
Judgeable
CastlesHard8
Tree, DFS +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
The IslandsHard8
Dynamic programming, Geometry +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Sharing ChocolateHard8
Dynamic programming, Bit manipulation +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
CardiologyHard8
Math, Number theory +1No attempts yetTime limit2sMemory limit2048 MB
Judgeable
DomesHard8
Geometry, Combinatorics +2No attempts yetTime limit2sMemory limit2048 MB
Judgeable
Ley LinesHard8
Geometry, Sorting +2No attempts yetTime limit15sMemory limit2048 MB
Judgeable
Opportunity CostHard8
Geometry, Binary search +2No attempts yetTime limit5sMemory limit2048 MB
Judgeable
QuestsHard8
Dynamic programming, Greedy +2No attempts yetTime limit10sMemory limit2048 MB
Judgeable
’S No ProblemHard8
Tree, DFS +2No attempts yetTime limit2sMemory limit2048 MB
Judgeable
Trailing DigitsHard8
Number theory, Math +2No attempts yetTime limit1sMemory limit2048 MB
Judgeable
Limited CorrespondenceHard8
DFS, Backtracking +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Conduit PackingHard8
Geometry, Math +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Best StudentHard8
Divide and conquer, Segment tree +2No attempts yetTime limit1.2sMemory limit1024 MB
Judgeable
Colorful Tower of HanoiHard8
Dynamic programming, Recursion +1No attempts yetTime limit1sMemory limit1024 MB
Judgeable
HistogramHard8
Dynamic programming, Prefix sum +2No attempts yetTime limit3sMemory limit1024 MB
Judgeable
Logistical WarehouseHard8
Tree, Binary search +2No attempts yetTime limit4sMemory limit1024 MB
Judgeable
SimilarityHard8
Divide and conquer, Sorting +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Twenty-ThreeHard8
Math, Dynamic programming +2No attempts yetTime limit2.3sMemory limit1023 MB
Judgeable
Night LetterHard8
Shortest path, Graph +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Deceptive DirectionsHard8
BFS, Graph +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Hiring HelpHard8
Geometry, Divide and conquerNo attempts yetTime limit4sMemory limit1024 MB
Judgeable
Intact IntervalsHard8
Array, Hash map +2No attempts yetTime limit6sMemory limit1024 MB
Judgeable
Line Fighter 2Hard8
Geometry, Divide and conquer +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
SquaresHard8
Number theory, Math +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Elevator OperationHard8
Graph, Greedy +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
W3W (What 3 Words)Hard8
String, Trie +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Cell DivisionHard8
Dynamic programming, Intervals +2No attempts yetTime limit3sMemory limit512 MB
Judgeable
K-CalculatorHard8
Linked list, Math +2No attempts yetTime limit1.5sMemory limit512 MB
Judgeable
Minimum Spanning CactusHard8
Graph, Tree +2No attempts yetTime limit1.2sMemory limit512 MB
Judgeable
Matrix PartitionHard8
Binary search, Brute force +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Hard All-Pairs Shortest PathHard8
Graph, Union-find +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Marble LaunchersHard8
Graph, Shortest path +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Matrix Partition 2Hard8
Dynamic programming, Prefix sum +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
DigionHard8
Recursion, Combinatorics +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
FlipHard8
Segment tree, Prefix sum +2No attempts yetTime limit3sMemory limit1024 MB
Judgeable
A Hard ProblemHard8
Bit manipulation, Graph +2No attempts yetTime limit20sMemory limit1024 MB
Judgeable
ICPC KingdomHard8
Graph, Shortest path +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Sequence OperationsHard8
Simulation, ImplementationNo attempts yetTime limit1sMemory limit512 MB
Judgeable
ConstructionHard8
Tree, DFS +2No attempts yetTime limit5sMemory limit512 MB
Judgeable
Beautiful WordsHard8
String matching, Trie +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Inverting EverythingHard8
Math, Tree +1No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Just BootfallHard8
Dynamic programming, Graph +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Listing PasswordsHard8
Union-find, String +1No attempts yetTime limit3sMemory limit1024 MB
Judgeable
Festive BaobabHard8
Tree, Greedy +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
ToteHard8
Dynamic programming, Probability +2No attempts yetTime limit2sMemory limit256 MB
Judgeable
Wooden pipelineHard8
Tree, DFS +2No attempts yetTime limit3sMemory limit256 MB
Judgeable
Pulse NovaHard8
Geometry, Brute forceNo attempts yetTime limit20sMemory limit256 MB
Judgeable
Russian Dolls on the Christmas TreeHard8
DFS, Segment tree +2No attempts yetTime limit3sMemory limit1024 MB
Judgeable
FireHard8
Binary search, Tree +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
FlowHard8
Graph, Greedy +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
HappinessHard8
Brute force, Sorting +2No attempts yetTime limit5sMemory limit256 MB
Judgeable
ValueHard8
Number theory, Dynamic programming +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
The WitcherHard8
Graph, Union-find +2No attempts yetTime limit6sMemory limit512 MB
Judgeable
All in good fun!Hard8
Geometry, Binary search +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
CheatHard8
Graph, DFS +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Yosupo's AlgorithmHard8
Sorting, Segment treeNo attempts yetTime limit4sMemory limit1024 MB
Judgeable
CookiesHard8
Simulation, Sorting +1No attempts yetTime limit3sMemory limit1024 MB
Judgeable
Sum ModuloHard8
Math, Probability +1No attempts yetTime limit4sMemory limit1024 MB
Judgeable
Xor SumHard8
Bit manipulation, Binary search +1No attempts yetTime limit2sMemory limit1024 MB
Judgeable
RobotsHard8
Dynamic programming, Greedy +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Matrix InversionHard8
Matrix, Math +1No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Balanced Binary StringHard8
String, Combinatorics +2No attempts yetTime limit3sMemory limit512 MB
Judgeable
Longest Lyndon PrefixHard8
String, String matching +1No attempts yetTime limit1sMemory limit256 MB
Judgeable
Program OptimizationHard8
Simulation, Segment tree +1No attempts yetTime limit2sMemory limit256 MB
Judgeable
Knocking DownHard8
Geometry, Sorting +1No attempts yetTime limit1sMemory limit64 MB
Judgeable
RatsHard8
String, Graph +2No attempts yetTime limit0.75sMemory limit256 MB
Judgeable
CoinsHard8
Math, Greedy +2No attempts yetTime limit1sMemory limit128 MB
Judgeable
CakesHard8
Binary search, Greedy +2No attempts yetTime limit3sMemory limit512 MB
Judgeable
Partial SumsHard8
Math, Number theory +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
Paternity TestingHard8
Tree, DFS +2No attempts yetTime limit3sMemory limit512 MB
Judgeable
Broken SequenceHard8
Backtracking, Brute force +1No attempts yetTime limit4sMemory limit64 MB
Judgeable
Format a TableHard8
Brute force, Math +1No attempts yetTime limit5sMemory limit64 MB
Judgeable
Game with DominoesHard8
Game theory, Sorting +2No attempts yetTime limit1sMemory limit64 MB
Judgeable
Everyone Loves Playing GamesHard8
Game theory, Bit manipulation +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
Gifted ComposerHard8
String matching, StringNo attempts yetTime limit4sMemory limit256 MB
Judgeable
Yet Another Geometry ProblemHard8
Geometry, Sorting +1No attempts yetTime limit4sMemory limit256 MB
Judgeable
A Math ProblemHard8
Math, CombinatoricsNo attempts yetTime limit1sMemory limit256 MB
Judgeable
Ant ColoniesHard8
Tree, Segment tree +1No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Friendship GraphsHard8
Graph, Dynamic programming +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Security SystemHard8
Geometry, Greedy +1No attempts yetTime limit0.8sMemory limit1024 MB
Judgeable
Rainy DayHard8
Minimum spanning tree, Graph +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Distance in CrossesHard8
Math, Geometry +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Galactic GovernmentsHard8
Backtracking, Brute force +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
MultiplicationHard8
Math, Number theory +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
PackageHard8
Graph, Two pointers +1No attempts yetTime limit2sMemory limit256 MB
Judgeable
Vasya's graphHard8
Union-find, Graph +2No attempts yetTime limit2sMemory limit256 MB
Judgeable
Maximum Coefficient of a Key RoadHard8
Graph, Minimum spanning tree +2No attempts yetTime limit8sMemory limit256 MB
Judgeable
Magical MazeHard8
Graph, Dynamic programming +1No attempts yetTime limit1.5sMemory limit512 MB
Judgeable
Error in codeHard8
Shortest path, Graph +2No attempts yetTime limit5sMemory limit256 MB
Judgeable
Level checkHard8
Graph, BFS +2No attempts yetTime limit4sMemory limit256 MB
Judgeable
What a Horrible and Dreadful FormulaHard8
String, Implementation +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
Gifts from SantaHard8
Dynamic programming, Prefix sum +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Color NumbersHard8
Bit manipulation, Dynamic programmingNo attempts yetTime limit1sMemory limit512 MB
Judgeable
Tower DefenseHard8
Tree, Divide and conquer +1No attempts yetTime limit5sMemory limit1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Dynamic Short PathOn a complete directed graph with weights 0 to 2, answer shortest distances capped at 2 for each query and apply up to 2000 edge weight updates.	Hard8	Shortest pathGraph+1	No attempts yet	7.5s	1024 MB	Judgeable
Equivalent PipelinesGiven d weighted spanning trees on n vertices, two trees are equivalent when the minimum edge weight on the path between every pair of vertices is the same; group each tree with the earliest equivalent one.	Hard8	Union-findSorting+2	No attempts yet	3s	1024 MB	Judgeable
Flowerbed RedecorationGiven a grid and a sliding d by d window that rotates 90 degrees clockwise at each stop, output the grid after the full scan order is applied.	Hard8	SimulationMatrix+1	No attempts yet	3s	1024 MB	Judgeable
Organizing BeadsAfter each toggle of a cell, report the minimum pushes to gather all beads into a contiguous block at the left or right end of the barrel.	Hard8	Prefix sumSorting+2	No attempts yet	2s	1024 MB	Judgeable
Periodic RulerGiven colors at up to 50 integer positions, find every positive integer that cannot be the minimal period of the full coloring, and report how many such numbers exist and their sum.	Hard8	MathNumber theory+2	No attempts yet	2s	1024 MB	Judgeable
Three CompetitionsEach person has ranks in three competitions; a directly wins against b if a beats b in at least two, and queries ask whether a reaches b through such direct wins.	Hard8	GraphSorting+2	No attempts yet	5s	1024 MB	Judgeable
CastlesGiven a tree of castles with attack, death, and garrison costs, find the smallest army that can capture and hold every castle while traversing each edge at most twice.	Hard8	TreeDFS+2	No attempts yet	2s	1024 MB	Judgeable
The IslandsTwo monotone passes across islands in increasing x order visit every island, with the two special islands split between the passes; find the shortest total tour and print the visiting order.	Hard8	Dynamic programmingGeometry+2	No attempts yet	2s	1024 MB	Judgeable
Sharing ChocolateDecide whether a rectangular chocolate bar can be broken along grid lines into exactly n rectangular pieces with given sizes, using each piece once.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	2s	1024 MB	Judgeable
CardiologyGiven r rows and c columns, choose the column to collect second so the stable position is nearest the center, and report that position and the iteration count.	Hard8	MathNumber theory+1	No attempts yet	2s	2048 MB	Judgeable
DomesGiven n domes inside a rectangle and a target left-to-right order, find the area of points in the rectangle from which the domes appear in that order in a 180-degree photo.	Hard8	GeometryCombinatorics+2	No attempts yet	2s	2048 MB	Judgeable
Ley LinesGiven n points with no three collinear and a pencil thickness t, find the largest number of points that can be covered by a single strip of width t.	Hard8	GeometrySorting+2	No attempts yet	15s	2048 MB	Judgeable
Opportunity CostGiven n triples, find the point minimizing the maximum over all points of the sum of positive coordinate gaps, and report its index.	Hard8	GeometryBinary search+2	No attempts yet	5s	2048 MB	Judgeable
QuestsOrder all n quests to maximize total XP, where a quest finished below its target level d pays c times its XP instead of x.	Hard8	Dynamic programmingGreedy+2	No attempts yet	10s	2048 MB	Judgeable
’S No ProblemGiven a weighted tree, place two routes (closed walks, ends free) that together cover every edge, minimizing total length.	Hard8	TreeDFS+2	No attempts yet	2s	2048 MB	Judgeable
Trailing DigitsGiven a per-item price b, a digit d, and a huge maximum price a, find the largest count of trailing d's achievable by a multiple of b not exceeding a.	Hard8	Number theoryMath+2	No attempts yet	1s	2048 MB	Judgeable
Limited CorrespondenceGiven up to 11 pairs of strings, find the shortest non-empty sequence of distinct pair indices whose concatenated left strings equal the concatenated right strings, breaking ties lexicographically.	Hard8	DFSBacktracking+2	No attempts yet	1s	1024 MB	Judgeable
Conduit PackingGiven four wire diameters, find the smallest enclosing circle diameter that holds all four circular cross sections without overlap, and round it to the nearest micrometer.	Hard8	GeometryMath+2	No attempts yet	2s	1024 MB	Judgeable
Best StudentFor each query interval in an array of student ids, print the id that occurs most often, breaking ties by the largest id.	Hard8	Divide and conquerSegment tree+2	No attempts yet	1.2s	1024 MB	Judgeable
Colorful Tower of HanoiFind the fewest moves to shift a Hanoi tower with repeated disk sizes, where each color sets whether that size's order must reverse, stay, or not matter.	Hard8	Dynamic programmingRecursion+1	No attempts yet	1s	1024 MB	Judgeable
HistogramGiven a frequency array over values 1..n, split it into at most B contiguous buckets minimizing the total sum of squared deviations from each bucket's mean.	Hard8	Dynamic programmingPrefix sum+2	No attempts yet	3s	1024 MB	Judgeable
Logistical WarehouseChoose k centers at integer points on a weighted tree to minimize the maximum weighted distance from any node to its nearest center.	Hard8	TreeBinary search+2	No attempts yet	4s	1024 MB	Judgeable
SimilarityGiven two length-n sequences p and q, count triples i<j<k with p_i<p_j<p_k and q_i<q_j<q_k.	Hard8	Divide and conquerSorting+2	No attempts yet	1s	1024 MB	Judgeable
Twenty-ThreeFind the k-th smallest number that can be written as a sum of repunit-like numbers made only of the digits 2 and 3 (23, 2323, ...).	Hard8	MathDynamic programming+2	No attempts yet	2.3s	1023 MB	Judgeable
Night LetterFor each query (C, s, e), find the shortest path from s to e that avoids intermediate houses with index at least C.	Hard8	Shortest pathGraph+2	No attempts yet	1s	1024 MB	Judgeable
Deceptive DirectionsGiven a grid and a sabotaged instruction string where each step was replaced by a different direction, mark every cell that could be the treasure.	Hard8	BFSGraph+2	No attempts yet	2s	1024 MB	Judgeable
Hiring HelpFor each consultant request, decide whether the current coders can match its lines and bugs per hour, with coders removed over time.	Hard8	GeometryDivide and conquer	No attempts yet	4s	1024 MB	Judgeable
Intact IntervalsCount the ways to cut a circular array into at least two contiguous arcs so that each arc's multiset equals the corresponding multiset of the target array b.	Hard8	ArrayHash map+2	No attempts yet	6s	1024 MB	Judgeable
Line Fighter 2Given N lines and Q queries (x, a), output the maximum (a=1) or minimum (a=2) value among all lines at x, within 1e-4 error.	Hard8	GeometryDivide and conquer+2	No attempts yet	1s	1024 MB	Judgeable
SquaresGiven N up to 10^18 whose prime factors are all at most 100000, output four non-negative integers whose squares sum to N.	Hard8	Number theoryMath+2	No attempts yet	2s	1024 MB	Judgeable
Elevator OperationEach floor holds one person with a known destination; drive a one-person elevator from floor 1 so everyone reaches their target floor using the fewest button presses, and output one optimal button order.	Hard8	GraphGreedy+2	No attempts yet	1s	512 MB	Judgeable
W3W (What 3 Words)Count how many distinct ordered triples of words (repetition allowed) can be joined with dots to form a code whose dot-stripped version equals the queried string S.	Hard8	StringTrie+2	No attempts yet	1s	512 MB	Judgeable
Cell DivisionGiven a mutation rule for each of N cell types and an initial cell, decide whether the observed final string could have been produced by the division process.	Hard8	Dynamic programmingIntervals+2	No attempts yet	3s	512 MB	Judgeable
K-CalculatorEvaluate an expression of rational operands by repeatedly applying the operator selected by u_i XOR the modular value of the previous result, removing it and merging its operands.	Hard8	Linked listMath+2	No attempts yet	1.5s	512 MB	Judgeable
Minimum Spanning CactusGiven a weighted cactus graph, print the minimum-cost spanning cactus, then after each edge-weight update print the new minimum spanning cactus cost.	Hard8	GraphTree+2	No attempts yet	1.2s	512 MB	Judgeable
Matrix PartitionCut an n by m grid with exactly a horizontal and b vertical cuts, maximizing no piece, and report the smallest possible largest piece sum.	Hard8	Binary searchBrute force+2	No attempts yet	1s	1024 MB	Judgeable
Hard All-Pairs Shortest PathIn a connected graph where exactly one edge has weight 1 and all others weight 0, compute the sum of shortest-path distances over all vertex pairs.	Hard8	GraphUnion-find+2	No attempts yet	1s	1024 MB	Judgeable
Marble LaunchersRotate marble launchers at per-45-degree cost so a marble fired from launcher s reaches launcher e, minimizing total rotation cost and outputting the path.	Hard8	GraphShortest path+2	No attempts yet	1s	1024 MB	Judgeable
Matrix Partition 2Given an n by m matrix, choose a horizontal and b vertical cut lines so the largest sum among the resulting parts is minimized.	Hard8	Dynamic programmingPrefix sum+2	No attempts yet	2s	1024 MB	Judgeable
DigionGiven a Digion string built from nesting rule (A)B, output the next Digion in the weight-then-inner-then-outer ordering.	Hard8	RecursionCombinatorics+2	No attempts yet	2s	1024 MB	Judgeable
FlipMaintain a binary array under range bit flips and report how many subarrays inside a query range are alternating.	Hard8	Segment treePrefix sum+2	No attempts yet	3s	1024 MB	Judgeable
A Hard ProblemAssign values to unknown nodes of a graph so that xor-popcount edge weights are minimized while q bit-level equality constraints hold.	Hard8	Bit manipulationGraph+2	No attempts yet	20s	1024 MB	Judgeable
ICPC KingdomPick exactly k roads that form no cycle and can each be assigned to a different worker, maximizing the sum of floor(sqrt(a_u + a_v)) for each k.	Hard8	GraphShortest path+2	No attempts yet	2s	1024 MB	Judgeable
Sequence OperationsDecide whether sequence C can be turned into D by inserting or deleting strictly increasing runs of length at least M, and output the operations.	Hard8	SimulationImplementation	No attempts yet	1s	512 MB	Judgeable
ConstructionGiven a tree, answer queries asking whether two vertices stay connected after deleting a single vertex or a single tree edge.	Hard8	TreeDFS+2	No attempts yet	5s	512 MB	Judgeable
Beautiful WordsGiven a string A and a set of strings S, find the minimum over all cyclic rotations of A of the longest substring that appears in some string of S.	Hard8	String matchingTrie+2	No attempts yet	1s	1024 MB	Judgeable
Inverting EverythingCount the city subsets whose flipping turns the active railroads of a complete graph into a spanning tree, modulo 1e9+7.	Hard8	MathTree+1	No attempts yet	1s	1024 MB	Judgeable
Just BootfallAssign N players to M ordered positions, scoring each player's position value minus C times the distance for every best-friend pair, and maximize total team performance.	Hard8	Dynamic programmingGraph+2	No attempts yet	1s	1024 MB	Judgeable
Listing PasswordsCount the 0/1 strings of length N that fit the fixed digits and M required palindrome intervals, modulo 1e9+7, or 0 on conflict.	Hard8	Union-findString+1	No attempts yet	3s	1024 MB	Judgeable
Festive BaobabPlace t unit-weight decorations on nodes of a rooted tree; each node i allows total weight in its subtree up to w_i, and each decoration on node i gives d_i joy. Maximize total joy.	Hard8	TreeGreedy+2	No attempts yet	2s	512 MB	Judgeable
ToteGiven match outcome probabilities and ticket types with fixed counts of single, double and triple bets, choose how many tickets of each type to buy within budget S to maximize expected prize money.	Hard8	Dynamic programmingProbability+2	No attempts yet	2s	256 MB	Judgeable
Wooden pipelineFor each city u in a tree, root the tree at u, then find the maximum flow from all leaves to u when only leaves can supply water.	Hard8	TreeDFS+2	No attempts yet	3s	256 MB	Judgeable
Pulse NovaPlace a circle of radius R so that the total length of the given lines' segments inside the circle is maximized.	Hard8	GeometryBrute force	No attempts yet	20s	256 MB	Judgeable
Russian Dolls on the Christmas TreeFor each node of a tree, consider the set of labels in its subtree and report the largest number of consecutive labels that can be chained into a stable nesting.	Hard8	DFSSegment tree+2	No attempts yet	3s	1024 MB	Judgeable
FireGiven a tree whose vertex temperatures drop by 1 each morning, find the latest day Pang can prepare to leave vertex 1 and still cast magic once on every vertex, or report -1.	Hard8	Binary searchTree+2	No attempts yet	1s	256 MB	Judgeable
FlowGiven a graph that is k vertex-independent paths from 1 to n, move capacity between edges at unit cost to maximize the max flow, and output the minimum number of moves.	Hard8	GraphGreedy+2	No attempts yet	1s	256 MB	Judgeable
HappinessGiven other teams' submission data, choose the order Pang solves his known problems (each takes a fixed time plus 20 penalty per rejection) to maximize his total happiness from ranking, medals, and special first/last-solve bonuses.	Hard8	Brute forceSorting+2	No attempts yet	5s	256 MB	Judgeable
ValueChoose a subset of 1..n maximizing the sum of a_i minus b_j for every selected pair where j is a higher power of i.	Hard8	Number theoryDynamic programming+2	No attempts yet	1s	256 MB	Judgeable
The WitcherGiven an undirected multigraph where some edges are mandatory, choose a subset of optional edges so that every vertex ends up with even degree, or report that this is impossible.	Hard8	GraphUnion-find+2	No attempts yet	6s	512 MB	Judgeable
All in good fun!Given three non-parallel lines, find the minimum possible value of the largest distance from a point to any of the three lines.	Hard8	GeometryBinary search+2	No attempts yet	1s	512 MB	Judgeable
CheatGiven a directed graph with edges i to i+1, list every vertex that lies on all cycles, or all vertices if the graph has no cycle.	Hard8	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
Yosupo's AlgorithmGiven red and blue weighted points, answer each query by picking a red and a blue point that satisfy the y-order and L, R split conditions, maximizing their total weight.	Hard8	SortingSegment tree	No attempts yet	4s	1024 MB	Judgeable
CookiesFor each k, find the total sweetness left after M children each add a cookie and eat the sweetest or bitterest one, with the input decrypted online.	Hard8	SimulationSorting+1	No attempts yet	3s	1024 MB	Judgeable
Sum ModuloGiven a generator that outputs 1 to N with weights A_i, find the expected number of draws until the running sum modulo M first equals K, printed modulo 998244353.	Hard8	MathProbability+1	No attempts yet	4s	1024 MB	Judgeable
Xor SumFind the minimum possible maximum of N nonnegative integers whose sum is S and whose XOR is X, or report -1 if no such sequence exists.	Hard8	Bit manipulationBinary search+1	No attempts yet	2s	1024 MB	Judgeable
RobotsGiven N robots and N antennas on a line, activate antennas one at a time so each pulls its nearest remaining robot; minimize total distance moved and output an order.	Hard8	Dynamic programmingGreedy+2	No attempts yet	2s	1024 MB	Judgeable
Matrix InversionFill an N by N grid with the integers 1 to N^2 so that the inversion number of the row-major reading is X and the column-major reading is Y, or report that it is impossible.	Hard8	MatrixMath+1	No attempts yet	1s	1024 MB	Judgeable
Balanced Binary StringCount the ways to replace each '?' in a circular binary string with 0 or 1 so that every two circular substrings of the same length contain numbers of 1s differing by at most one, modulo 1e9+7.	Hard8	StringCombinatorics+2	No attempts yet	3s	512 MB	Judgeable
Longest Lyndon PrefixFor each suffix of a lowercase string, find the length of its longest prefix that is a Lyndon word.	Hard8	StringString matching+1	No attempts yet	1s	256 MB	Judgeable
Program OptimizationSimulate the given C++ program exactly, including its mt19937 random sequence, while answering range mex queries over a permuted array fast enough for q up to 10^7.	Hard8	SimulationSegment tree+1	No attempts yet	2s	256 MB	Judgeable
Knocking DownPick one point of a rectangle to pin, rotate it around that point, and find the fewest flags the sweep must knock down.	Hard8	GeometrySorting+1	No attempts yet	1s	64 MB	Judgeable
RatsGiven an infinite periodic string A and a set S of strings, find the minimum number of strings from S whose concatenation forms a string B that tiles the line identically to A.	Hard8	StringGraph+2	No attempts yet	0.75s	256 MB	Judgeable
CoinsPlace N coins on an N by N board so each row and column holds one coin, moving coins one step at a time with no collisions, and minimize total moves.	Hard8	MathGreedy+2	No attempts yet	1s	128 MB	Judgeable
CakesThree eaters with different per-cake speeds share n cakes, each cake splittable into any proportions; find the minimum makespan.	Hard8	Binary searchGreedy+2	No attempts yet	3s	512 MB	Judgeable
Partial SumsRepeatedly apply the 2D prefix-sum map over GF(2) to a binary matrix and find the smallest positive number of applications that returns the original matrix.	Hard8	MathNumber theory+2	No attempts yet	1s	256 MB	Judgeable
Paternity TestingGiven a rooted tree, answer queries that sum cnt(i, l, r) over i in [l, r], where cnt counts subtree nodes with labels in a range; queries are encoded online by the previous answer.	Hard8	TreeDFS+2	No attempts yet	3s	512 MB	Judgeable
Broken SequenceFill in the missing +1 and -1 values of four partly known sequences so that they form a Turyn-type sequence.	Hard8	BacktrackingBrute force+1	No attempts yet	4s	64 MB	Judgeable
Format a TableGiven a 3x3 table of cell text lengths and a total width w, split w into three column widths that minimize the sum of the three row heights.	Hard8	Brute forceMath+1	No attempts yet	5s	64 MB	Judgeable
Game with DominoesGiven n domino positions, choose a height h' in [hmin,hmax] that makes the second player win a game where each move topples a contiguous chain; output the smallest such h' or -1.	Hard8	Game theorySorting+2	No attempts yet	1s	64 MB	Judgeable
Everyone Loves Playing GamesTwo players alternately XOR one chosen value from each of their pairs into a running total; the first maximizes the final result and the second minimizes it, both playing optimally.	Hard8	Game theoryBit manipulation+2	No attempts yet	1s	256 MB	Judgeable
Gifted ComposerAfter each prepend or append, count the lengths k for which the note sequence is a repetition of period k, with a partial final block allowed.	Hard8	String matchingString	No attempts yet	4s	256 MB	Judgeable
Yet Another Geometry ProblemFor each query point, find the largest axis-parallel integer square inside the M by M plane that strictly contains the point and no given point strictly.	Hard8	GeometrySorting+1	No attempts yet	4s	256 MB	Judgeable
A Math ProblemCount the fan-to-team assignments for n fans and m teams where the fan sets are closed under pairwise intersection and union, modulo 10^9+7.	Hard8	MathCombinatorics	No attempts yet	1s	256 MB	Judgeable
Ant ColoniesGiven a colored tree and a sequence of color updates, find the smallest distance between two same-colored colonies on the path between A and B, or -1 if none exists.	Hard8	TreeSegment tree+1	No attempts yet	2s	1024 MB	Judgeable
Friendship GraphsSplit a graph's vertices into two cliques, minimizing the size difference between them, or report that no such split exists.	Hard8	GraphDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
Security SystemFind the minimum number of non-touching horizontal or vertical tracks that let sensors watch every point of an x-monotone rectilinear polygon.	Hard8	GeometryGreedy+1	No attempts yet	0.8s	1024 MB	Judgeable
Rainy DayBuild skybridges so every building is reachable, where building i with degree k costs a_i*k^2, and minimize total cost.	Hard8	Minimum spanning treeGraph+2	No attempts yet	1s	1024 MB	Judgeable
Distance in CrossesSquares are tiled by crosses whose centers form a lattice; moving to a different cross costs one coin, and we must find the minimum coins between two given squares.	Hard8	MathGeometry+2	No attempts yet	2s	512 MB	Judgeable
Galactic GovernmentsGiven up to 18 axis-aligned boxes in k up to 10 dimensions, find a half-integer lattice point not covered by any box, choosing the lexicographically smallest.	Hard8	BacktrackingBrute force+2	No attempts yet	2s	512 MB	Judgeable
MultiplicationGiven an even n, output n distinct numbers so that after multiplying by a secret odd x mod 2^31, the judge returns half of the products, and you must recover x.	Hard8	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
PackageChoose one version per application so that no conflict contains two chosen packages; conflicts are disjoint package sets, so model each application as a vertex in a graph where a conflict forces a specific version.	Hard8	GraphTwo pointers+1	No attempts yet	2s	256 MB	Judgeable
Vasya's graphGiven K forbidden node pairs and M edges offered in order, keep each edge only if it does not connect any forbidden pair, and report which edges are kept.	Hard8	Union-findGraph+2	No attempts yet	2s	256 MB	Judgeable
Maximum Coefficient of a Key RoadFor each edge, find the largest value its weight can take while still belonging to some minimum spanning tree of the graph.	Hard8	GraphMinimum spanning tree+2	No attempts yet	8s	256 MB	Judgeable
Magical MazeCount ordered pairs of chambers (x, y) that both lie on some path from the entrance to the exit of a one-way grid maze, where y is reachable from x.	Hard8	GraphDynamic programming+1	No attempts yet	1.5s	512 MB	Judgeable
Error in codeGiven the output of a buggy Floyd-Warshall variant that only loops w, u, v up to N-1, recover the true all-pairs shortest path matrix.	Hard8	Shortest pathGraph+2	No attempts yet	5s	256 MB	Judgeable
Level checkGiven a fixed passable-cell map, decide for each layout whether the player can always reach a weapon before any monster, considering adversarial monster movement.	Hard8	GraphBFS+2	No attempts yet	4s	256 MB	Judgeable
What a Horrible and Dreadful FormulaGiven a string where digits were replaced by English number words, recover the original arithmetic expression or report that none exists, then evaluate it left to right.	Hard8	StringImplementation+2	No attempts yet	1s	256 MB	Judgeable
Gifts from SantaPartition a prefix of the gift sequence into K consecutive nonempty blocks, each child getting one block, minimizing the sum over blocks of (block sum minus the smallest block sum).	Hard8	Dynamic programmingPrefix sum+2	No attempts yet	1s	512 MB	Judgeable
Color NumbersFind the fewest colors for an array so that no pair, where one value is a bitwise submask of the other and their XOR has at least k set bits, shares a color.	Hard8	Bit manipulationDynamic programming	No attempts yet	1s	512 MB	Judgeable
Tower DefensePick a city in a tree so every tower covers it, where raising a tower's radius by x costs ceil(x/k), minimizing the total cost.	Hard8	TreeDivide and conquer+1	No attempts yet	5s	1024 MB	Judgeable