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Total results29,413 problems

Möbius Madness
Hard8
Math, Number theory+1
No attempts yet
Time limit
2.5s
Memory limit
512 MB
Judgeable
Liar Game
Hard8
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Coloring Roads
Hard8
Tree, Segment tree+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Electronic Circuit
Hard8
Graph, Hash map+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Fake Plastic Trees
Hard8
Tree, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Game on Plane
Hard8
Game theory, Geometry
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Utilitarianism
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Balcony Repairs
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Finding Tricky Numbers
Hard8
Dynamic programming, Binary search+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Laziness
Hard8
Math, Greedy+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Baek Chaewon
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Build a Wall!
Hard8
Dynamic programming, Geometry+1
No attempts yet
Time limit
2.5s
Memory limit
1024 MB
Judgeable
Sorting Game
Hard8
Array, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Clusters
Hard8
Dynamic programming, Prefix sum+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
We Live Forgetting the Truth
Hard8
Graph, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Teoretičar
Hard8
Graph, Divide and conquer+1
No attempts yet
Time limit
8s
Memory limit
256 MB
Judgeable
Rangers in the Bus
Hard8
Simulation, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Slalom
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Array Covering
Hard8
Greedy, Heap+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Memory Manager
Hard8
Greedy, Dynamic programming+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Red-Black Tree
Hard8
Dynamic programming, Tree+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Array Study
Hard8
Prefix sum, Divide and conquer+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Nice Report
Hard8
Graph, Probability+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Small Numbers
Hard8
Number theory, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Folding the Figure
Hard8
Implementation, Geometry+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Two Trees
Hard8
Tree, Hash map+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Similar Words
Hard8
Trie, Tree+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Eleventh Birthday
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Masha and Cactus
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Panokseon
Hard8
Greedy, Binary search+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Parcel
Hard8
Two pointers, Hash map+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Suffix-Freeness
Hard8
String matching, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Eating Everything Efficiently
Hard8
Dynamic programming, Graph+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Isomorphic Inversion
Hard8
Greedy, String matching+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
KALLAX Construction
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Harry the Hamster
Hard8
Game theory, Dynamic programming+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Kingpin Escape
Hard8
Tree, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Game Scheduling
Hard8
Graph, Greedy+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Intergalactic Bidding
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
King's Colors
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Broken Watch
Hard8
Math, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Tree
Hard8
Tree, Binary search+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Inversion
Hard8
Graph, Brute force+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Moving Furniture
Hard8
Geometry, Math
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Horsemeet
Hard8
Probability, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Lighting
Hard8
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Locker Room
Hard8
String, Greedy+2
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Numbers Generator
Hard8
String matching, Hash map+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Ghost Leg
Hard8
Segment tree, Array+1
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Plate
Hard8
Math, Simulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Tree in Tree
Hard8
Tree, DFS+2
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Cosmetic Survey
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
LED
Hard8
Binary search, Greedy+2
No attempts yet
Time limit
1.3s
Memory limit
512 MB
Judgeable
Parentheses
Hard8
Stack, Recursion+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Secret Code
Hard8
Combinatorics, Geometry+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
TV Show Game
Hard8
Dynamic programming, Brute force+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Chemical table
Hard8
Union-find, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Prime Tree - 5
Hard8
Greedy, Number theory+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Prime Tree - 8
Hard8
Tree, Greedy+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Repeated Substrings
Hard8
String matching, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Count the Bits
Hard8
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Knockout
Hard8
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Rectangles
Hard8
Segment tree, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
A/B - 3
Hard8
Math, Implementation+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Slackline Adventure
Hard8
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Gasoline
Hard8
Binary search, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Police Hypothesis
Hard8
Tree, String matching+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Joining Capitals
Hard8
Graph, Minimum spanning tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Kepler
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Metro Lines
Hard8
Tree, Linked list+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Modified SAT
Hard8
Dynamic programming, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Maple Leaf Story
Hard8
Brute force, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Decorating a Christmas Tree
Hard8
Dynamic programming, Tree+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
decrypt
Hard8
Bit manipulation, Math+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
cmp
Hard8
Bit manipulation, Binary search+2
No attempts yet
Time limit
10s
Memory limit
256 MB
Judgeable
Pikachu's Hard Problem
Hard8
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
k-Maximum Subarrays
Hard8
Dynamic programming, Divide and conquer+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Travel the Skies
Hard8
Graph, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tima goes to Xentopia
Hard8
Shortest path, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Escape, Polygon!
Hard8
Geometry, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Gathering Red-Black Fruits
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Looking for the Risk Factor
Hard8
Math, Number theory+2
No attempts yet
Time limit
0.2s
Memory limit
512 MB
Judgeable
Khans
Hard8
Dynamic programming, Hash map+2
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Superstition
Hard8
Graph, Matrix+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Pie Max Flow
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
A Sequence That Matches Front and Back
Hard8
Array, String matching+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Pixel Triangles
Hard8
Prefix sum, Matrix+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Rotating Gears
Hard8
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Icy Land
Hard8
Graph, Matrix+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Artilleries and Defensive Walls
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Go Make It Complete
Hard8
Graph, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Hierarchical Structure
Hard8
Tree, Binary search+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Discs
Hard8
Geometry, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Living Subgraph
Hard8
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Fair Tournament
Hard8
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Access Points
Hard8
Dynamic programming, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Brexit Negotiations
Hard8
Topological sort, Binary search+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Jinxed Betting
Hard8
Game theory, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Bad Keming
Hard8
String matching, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Dropping Blocks
Hard8
Greedy, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Möbius MadnessGiven N, L, and K, compute the sum over d from 1 to N of mu(L*d) times floor(N/d) to the power K, modulo 1e9+7.	Hard8	MathNumber theory+1	No attempts yet	2.5s	512 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
Electronic CircuitGiven an undirected multigraph, decide whether two end nodes can be chosen so that the circuit is built only by series and parallel composition.	Hard8	GraphHash map+1	No attempts yet	1s	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
Game on PlanePlayers alternately draw non-crossing segments between vertices of a regular N-gon, and the one who completes a convex polygon wins. Decide who should move first to force a win.	Hard8	Game theoryGeometry	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
Build a Wall!Given a convex N-gon and query points, find for each point the triangulation that maximizes how many diagonals must be crossed to reach it from outside.	Hard8	Dynamic programmingGeometry+1	No attempts yet	2.5s	1024 MB	Judgeable
Sorting GameAfter each swap of two positions, find the minimum rounds Aizan needs to sort the permutation while Ermac delays, or -1 if Ermac can always prevent sorting.	Hard8	ArrayMath+1	No attempts yet	1s	1024 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
TeoretičarColor the edges of a bipartite graph so adjacent edges differ, using at most the smallest power of 2 that is at least the maximum degree.	Hard8	GraphDivide and conquer+1	No attempts yet	8s	256 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
SlalomCount the right-or-up paths from (1, 1) to (n, m) that avoid rectangular obstacles, where each obstacle is passed on either side, modulo 10^9 + 7.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	2s	512 MB	Judgeable
Array CoveringChoose k distinct contiguous subarrays that together cover every array element so that the total of their sums is as large as possible, and output that maximum.	Hard8	GreedyHeap+1	No attempts yet	3s	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
Red-Black TreeCount the colorings of a binary tree's vertices that satisfy the red-black rules, with fake leaves added at missing children, modulo 1e9+7.	Hard8	Dynamic programmingTree+1	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
Nice ReportFor each vertex of a directed graph, estimate how many vertices it can reach, with each estimate within a factor of two of the exact count.	Hard8	GraphProbability+1	No attempts yet	5s	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
Two TreesGiven a rooted tree, find the largest k for which two k-subtrees with different roots are equal as ordered trees.	Hard8	TreeHash map+2	No attempts yet	4s	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
Game SchedulingGiven n players per team and m teams, build a round schedule where each player plays everyone outside their own team and has at most one bye.	Hard8	GraphGreedy+1	No attempts yet	3s	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
Moving FurnitureGiven 4N leg hollow coordinates from N square tables, find the total area of all tables, which the points alone determine.	Hard8	GeometryMath	No attempts yet	2s	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
Ghost LegGiven a ghost leg board where rungs get removed over time, answer for each query which line the player starting at line j ends on.	Hard8	Segment treeArray+1	No attempts yet	4s	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
LEDGiven n voltage and intensity pairs, the task finds a two-step step function that minimizes the maximum absolute error and prints that minimum error.	Hard8	Binary searchGreedy+2	No attempts yet	1.3s	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
Repeated SubstringsFind the longest substring with at least two overlapping occurrences in a string of up to 10^5 letters, breaking ties by the smallest in lexicographic order.	Hard8	String matchingString+2	No attempts yet	2s	512 MB	Judgeable
Count the BitsGiven k and b, count the total number of 1-bits in all multiples of k from 0 to 2^b-1, and print the sum modulo 10^9+9.	Hard8	Dynamic programmingBit manipulation+1	No attempts yet	2s	512 MB	Judgeable
KnockoutGiven remaining digits 1-9 and a dice total, choose a subset summing to that total that minimizes or maximizes the expected final number read from the leftover digits under optimal play.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
RectanglesGiven up to 100,000 axis-aligned rectangles drawn by XOR-flipping pixels on a white field, find the total count of black pixels.	Hard8	Segment treePrefix sum+2	No attempts yet	2s	512 MB	Judgeable
A/B - 3Given A and B with up to 10000 digits (possibly negative), compute the quotient and nonnegative remainder of A divided by B.	Hard8	MathImplementation+2	No attempts yet	0.5s	512 MB	Judgeable
Slackline AdventureCount unordered pairs of grid trees at distance in [L, R] whose line segment passes through no other tree, using visible lattice points and inclusion-exclusion over strip indices.	Hard8	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
GasolineGiven station demands, refinery stocks, and allowed refinery-station pairs with travel times, find the minimum time to fully supply every station, or -1 if impossible.	Hard8	Binary searchGraph+2	No attempts yet	2s	512 MB	Judgeable
Police HypothesisGiven a tree with one letter per vertex, count how often pattern P appears on the path between two vertices, and handle letter updates.	Hard8	TreeString matching+2	No attempts yet	2s	512 MB	Judgeable
Joining CapitalsConnect all capitals with degree exactly one through Steiner points (non-capitals) at minimum Euclidean total cost.	Hard8	GraphMinimum spanning tree+2	No attempts yet	2s	512 MB	Judgeable
KeplerGiven N circles that all enclose the origin, count their intersection points, or report greater if the count exceeds 2N.	Hard8	GeometrySorting+1	No attempts yet	2s	512 MB	Judgeable
Metro LinesA tree is given, and for each query with two pairs of terminals, count the stations shared by the two paths between those pairs.	Hard8	TreeLinked list+2	No attempts yet	2s	512 MB	Judgeable
Modified SATGiven a CNF formula whose clauses each have at most 3 literals, decide whether there is an assignment with exactly 1 or exactly 3 true literals per clause, and print the lexicographically largest such assignment.	Hard8	Dynamic programmingGreedy+1	No attempts yet	2s	512 MB	Judgeable
Maple Leaf StoryBind n skills of 2n to n keys so maximum quests each needing k skills all bound can be cleared. n <= 10, m <= 100.	Hard8	Brute forceCombinatorics+2	No attempts yet	1s	256 MB	Judgeable
Decorating a Christmas TreeCount binary trees with exactly L levels and N distinct nodes, ordered by level and by a preorder placement rule, modulo 100030001.	Hard8	Dynamic programmingTree+2	No attempts yet	1s	512 MB	Judgeable
decryptQuery a black-box encoder up to 320 times to recover three secret seeds of a linear recurrence and a secret byte permutation.	Hard8	Bit manipulationMath+2	No attempts yet	1s	64 MB	Judgeable
cmpStore which of 12-bit buckets hold the remembered 12-bit value with 4095 bits, then read 12 prefix sums to binary search the bucket and compare it by a 12-bit count table to fit 20 memory accesses.	Hard8	Bit manipulationBinary search+2	No attempts yet	10s	256 MB	Judgeable
Pikachu's Hard ProblemUse Stewart's theorem on isosceles ABC with equal legs N to prove F(i) = N^2, so the answer for any K points is floor(K*N^2).	Hard8	MathImplementation	No attempts yet	1s	512 MB	Judgeable
k-Maximum SubarraysPick k disjoint contiguous subarrays of an array with maximum total sum; output only that sum.	Hard8	Dynamic programmingDivide and conquer+2	No attempts yet	2s	512 MB	Judgeable
Travel the SkiesGiven flights with capacities between airports over a window of days, and customers starting at each airport-day, decide whether every flight can be filled to capacity when each customer flies at most once per day and may depart on or after their start day.	Hard8	GraphDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Tima goes to XentopiaFind the cheapest S-to-T walk using exactly k1 red and k2 blue edges, any number of white edges, with edges reusable.	Hard8	Shortest pathGraph+2	No attempts yet	2s	512 MB	Judgeable
Escape, Polygon!Given an integer convex polygon of up to 100000 vertices, count the triples of its sides whose supporting lines form a triangle containing the polygon. Output that count.	Hard8	GeometryCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Gathering Red-Black FruitsCount how many distinct rankings of N children can arise from scoring each red fruit r and black fruit b for some positive integers r, b.	Hard8	GeometrySorting+2	No attempts yet	2s	512 MB	Judgeable
Looking for the Risk FactorCount integers in [2, N] whose prime factors are all at most K, for up to 50000 queries on N and K up to 100000.	Hard8	MathNumber theory+2	No attempts yet	0.2s	512 MB	Judgeable
KhansFind the maximum food the khans can eat in K years walking on an N by M grid over growing cell values, never revisiting a cell before it returns to its maximum.	Hard8	Dynamic programmingHash map+2	No attempts yet	2s	64 MB	Judgeable
SuperstitionCount walks in a weighted undirected graph whose total travel time is a multiple of D and at most K, modulo 1,000,000,007.	Hard8	GraphMatrix+1	No attempts yet	2s	512 MB	Judgeable
Pie Max FlowGiven a wheel of N spokes from vertex 0 with capacities A and a rim cycle with capacities B, compute each sink's max flow from 0 and output their sum.	Hard8	GraphShortest path+2	No attempts yet	1s	256 MB	Judgeable
A Sequence That Matches Front and BackChoose how many elements to cut from the array's front so that, if the rest is a k-front-back sequence, k is as large as possible or no k exists. Return k and the cut count.	Hard8	ArrayString matching+1	No attempts yet	2s	128 MB	Judgeable
Pixel TrianglesGiven up to four million right isosceles triangles on a 2000x2000 grid, count the total number of grid cells covered by at least one triangle.	Hard8	Prefix sumMatrix+2	No attempts yet	2s	512 MB	Judgeable
Rotating GearsHandle gear removals, reinsertions, and rotations on a gear tree where touching gears turn oppositely. Print each rotation's energy and the final angle sum.	Hard8	TreeDFS+2	No attempts yet	1s	512 MB	Judgeable
Icy LandGiven an R by C grid of dry and icy cells, find the fewest icy cells to turn into dry land so that every cell can be visited from any starting position while sliding.	Hard8	GraphMatrix+1	No attempts yet	1s	512 MB	Judgeable
Artilleries and Defensive WallsFor each of up to 40000 tower positions below the border, count the artilleries whose line of sight avoids up to 5 horizontal walls.	Hard8	GeometrySorting+2	No attempts yet	1s	512 MB	Judgeable
Go Make It CompleteGiven a simple graph, find the largest k such that some ordering of the missing edges, adding a pair when its current endpoint degrees sum to at least k, still yields the complete graph.	Hard8	GraphGreedy+2	No attempts yet	1s	512 MB	Judgeable
Hierarchical StructureGiven a rooted tree of employees and queries (a,b,l,r), compute the sum of ages in [l,r] over all vertices on the path from a to b.	Hard8	TreeBinary search+2	No attempts yet	3s	512 MB	Judgeable
DiscsAssign nested discs to N given lattice centers and choose radii so every pair of discs is nested, minimizing the total radius sum.	Hard8	GeometryDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Living SubgraphFind the smallest node set whose induced subgraph is connected and stays connected after deleting any one of its nodes.	Hard8	GraphBFS+2	No attempts yet	1s	512 MB	Judgeable
Fair TournamentArrange 2^N players in a knockout bracket so player 1 wins every match, minimizing the sum of the efforts paid along the way; print -1 if impossible.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
Access PointsPlace n teams so both coordinates are nondecreasing along IDs, minimizing the sum of squared distances to fixed access points.	Hard8	Dynamic programmingDivide and conquer+2	No attempts yet	1s	512 MB	Judgeable
Brexit NegotiationsGiven a DAG of topics with base minutes, order them topologically so the meeting time (base plus the number done so far) minimizes the maximum meeting length.	Hard8	Topological sortBinary search+2	No attempts yet	3s	512 MB	Judgeable
Jinxed BettingGiven everyone's scores with Julia listed first, find how many more matches she is guaranteed to stay in the lead against worst-case bets and outcomes.	Hard8	Game theoryGreedy+1	No attempts yet	2s	512 MB	Judgeable
Bad KemingFill every gap in the spaced copy of S with chosen letters to make the longest prefix of S a contiguous substring, and find that prefix length.	Hard8	String matchingString+2	No attempts yet	2s	512 MB	Judgeable
Dropping BlocksGiven pile heights, decide whether prefix-wise operations (add 1 to a prefix or a suffix starting at k) can produce exactly that array, and say valid or invalid.	Hard8	GreedyMath+2	No attempts yet	2s	512 MB	Judgeable