Problems

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Total results29,417 problems

Looping Labyrinth
Hard8
Union-find, Graph+1
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Tour de France
Hard8
Backtracking, Graph
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
4 × 4 Torus Puzzle
Hard8
BFS, Graph+1
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Flight Plan Evaluation
Hard8
Geometry, Math
No attempts yet
Time limit
6s
Memory limit
256 MB
Judgeable
Hole in One
Hard8
Backtracking, Geometry+1
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Wooden Signs
Hard8
Dynamic programming, Combinatorics
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Text Processor
Hard8
String matching, Sliding window+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Digit Sum Depth
Hard8
Number theory, Math
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Skyland
Hard8
Graph, Math
No attempts yet
Time limit
5s
Memory limit
64 MB
Judgeable
Tree Allocation
Hard8
Dynamic programming, Tree+1
No attempts yet
Time limit
10s
Memory limit
64 MB
Judgeable
Balanced Paths
Hard8
Divide and conquer, Hash map+2
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Content Delivery
Hard8
Dynamic programming, Tree+1
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Cost Performance Flow
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
ICPC Teams
Hard8
Combinatorics, Union-find+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Midpoint
Hard8
Geometry, Math+1
No attempts yet
Time limit
10s
Memory limit
256 MB
Judgeable
Watering the fields
Hard8
Implementation, Backtracking+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Distance on Triangulation
Hard8
Divide and conquer, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Hypercube
Hard8
Backtracking, Geometry
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Jump
Hard8
Implementation, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
King's Inspection
Hard8
Graph, Backtracking+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Routing a Marathon Race
Hard8
Backtracking, Graph+2
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Post Office Investigation
Hard8
Graph, Tree
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Min-Max Distance Game
Hard8
Game theory, Greedy+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Niya's Happiness
Hard8
Segment tree, Sorting+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Queue of Soldiers
Hard8
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Sunlight on a Tree
Hard8
Tree, Segment tree+1
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Stop Making Sense
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Connect the Cells
Hard8
Backtracking, Graph+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Bike Sharing
Hard8
Graph, Binary search
No attempts yet
Time limit
10s
Memory limit
256 MB
Judgeable
High Jump
Hard8
Simulation, Backtracking
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
New Year Train
Hard8
Greedy, Queue+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Mountain Trek Route
Hard8
Greedy, Heap+1
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Substrings
Hard8
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Special graph
Hard8
Graph, Tree+1
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Round words
Hard8
Dynamic programming, String
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Longest Shortest Paths at Shymbulak
Hard8
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Marriage questions
Hard8
Graph, Two pointers
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Roads
Hard8
Union-find, Tree
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Guessing Game
Hard8
Dynamic programming, Binary search+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Rain Again
Hard8
Binary search, Segment tree+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Splitting Nim
Hard8
Game theory, Math
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Subsequence Hashes
Hard8
Heap, Sorting+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Birthday Numbers II
Hard8
Math, Recursion+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Edge Destruction
Hard8
Graph, Union-find+1
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Counting palindromes
Hard8
String matching, Segment tree+2
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Find the missing rank
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
32 MB
Judgeable
Swapping the Stones
Hard8
Greedy, String matching+1
No attempts yet
Time limit
2s
Memory limit
32 MB
Judgeable
Cabins
Hard8
Binary search, Divide and conquer+1
No attempts yet
Time limit
6s
Memory limit
64 MB
Judgeable
Guards
Hard8
Dynamic programming, Number theory+1
No attempts yet
Time limit
2s
Memory limit
32 MB
Judgeable
Connecting the wires
Hard8
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
K-th smallest weight on a tree path
Hard8
Segment tree, Tree+1
No attempts yet
Time limit
1.5s
Memory limit
512 MB
Judgeable
Fortune Telling 2
Hard8
Segment tree, Sorting+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Shopping
Hard8
Dynamic programming, Shortest path
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Mowing the Field
Hard8
Segment tree, Geometry+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Fault
Hard8
Segment tree, Geometry
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Alphabet Blocks and Passwords
Hard8
Backtracking, String matching+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Balloon Recovery
Hard8
Binary search, Dynamic programming
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Albocede DNA (Large)
Hard8
Dynamic programming, Combinatorics
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Tying All the Cards
Hard8
Minimum spanning tree, Number theory+1
No attempts yet
Time limit
5s
Memory limit
768 MB
Judgeable
Costly Binary Search (Large)
Hard8
Dynamic programming, Divide and conquer+1
No attempts yet
Time limit
60s
Memory limit
1536 MB
Judgeable
Campground Arrangements (Large)
Hard8
Combinatorics, Math
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Taking Over the World (Large)
Hard8
Shortest path, Graph
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Merlin QA (Large)
Hard8
Dynamic programming, Greedy+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Fairland (Large)
Hard8
Tree, Sliding window+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Runaway Quail
Hard8
Dynamic programming, Math+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Log Set (Large)
Hard8
Greedy, Sorting+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Drum Decorator (Small)
Hard8
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Drum Decorator (Large)
Hard8
Combinatorics, Graph+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Hiking Deer
Hard8
Math, Sorting+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Hiking Deer (Large)
Hard8
Greedy, Intervals+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Googlander (Large)
Hard8
Dynamic programming, Recursion+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Power Swapper
Hard8
Divide and conquer, Recursion+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
ARAM (Large)
Hard8
Dynamic programming, Probability+2
No attempts yet
Time limit
120s
Memory limit
512 MB
Judgeable
Willow (Large)
Hard8
Game theory, Tree+1
No attempts yet
Time limit
120s
Memory limit
512 MB
Judgeable
Don't Break the Nile (Large)
Hard8
Shortest path, Graph+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Trie Sharding
Hard8
Dynamic programming, Trie+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
The Bored Traveling Salesman (Large)
Hard8
DFS, Graph+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Hamiltonian path
Hard8
Graph, Greedy+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Let Me Tell You a Story (Large)
Hard8
Combinatorics, Dynamic programming
No attempts yet
Time limit
30s
Memory limit
512 MB
Judgeable
Observation Wheel (Large)
Hard8
Probability, Dynamic programming+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Ticket Swapping
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Many prizes
Hard8
Combinatorics, Math+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Multiplayer Pong (Large)
Hard8
Math, Game theory+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
The Great Wall (Large)
Hard8
Segment tree, Intervals+1
No attempts yet
Time limit
15s
Memory limit
512 MB
Judgeable
Falling Diamonds (Large)
Hard8
Probability, Simulation+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Fair and Square (Large2)
Hard8
Math, String+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Upstairs and Downstairs
Hard8
Probability, Dynamic programming+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Upstairs and Downstairs
Hard8
Probability, Greedy+1
No attempts yet
Time limit
100s
Memory limit
512 MB
Judgeable
Xeno-archaeology (Large)
Hard8
Math, Geometry+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Lost Password
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
The peak that looks highest
Hard8
Geometry, Backtracking+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Descending in the Dark (Large)
Hard8
Graph, BFS
No attempts yet
Time limit
40s
Memory limit
512 MB
Judgeable
Tide Goes In, Tide Goes Out (Large)
Hard8
Shortest path, Binary search+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Hall of Mirrors
Hard8
Geometry, Simulation
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Hall of Mirrors (Large)
Hard8
Geometry, Simulation+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Commute War (Large)
Hard8
Shortest path, Probability+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Yut Nori (Large)
Hard8
Backtracking, Simulation+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Houses on the Han River
Hard8
Number theory, Combinatorics
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Wildcard (Large)
Hard8
Dynamic programming, String matching+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Closet Room (Large)
Hard8
Dynamic programming, Graph+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Looping LabyrinthDecide for each of up to 200000 query cells whether a path through empty cells of an infinitely tiled grid reaches the origin.	Hard8	Union-findGraph+1	No attempts yet	4s	512 MB	Judgeable
Tour de FranceFind the shortest directed tour that visits each of up to 36 cities exactly once when every city has at most two outgoing and two incoming roads.	Hard8	BacktrackingGraph	No attempts yet	2s	256 MB	Judgeable
4 × 4 Torus PuzzleFind the fewest cyclic row or column shifts on the 4 by 4 torus grid that turn the given color layout into four solid color rows.	Hard8	BFSGraph+1	No attempts yet	5s	256 MB	Judgeable
Flight Plan EvaluationGiven continent polygons and flight waypoints on a sphere, compute the total flight length and the share flown over water.	Hard8	GeometryMath	No attempts yet	6s	256 MB	Judgeable
Hole in OneFind the most walls a ball shot from the origin can destroy by bouncing off axis-aligned walls before dropping into the hole.	Hard8	BacktrackingGeometry+1	No attempts yet	5s	256 MB	Judgeable
Wooden SignsCount the arrow stacks that match the given permutation, with each board screwed to the prior board so neighbors overlap, modulo 2147483647.	Hard8	Dynamic programmingCombinatorics	No attempts yet	1s	256 MB	Judgeable
Text ProcessorCount the distinct substrings inside each fixed-width window of a lowercase string for many queries.	Hard8	String matchingSliding window+1	No attempts yet	1s	256 MB	Judgeable
Digit Sum DepthGiven N, m, and base l, find the smallest positive integer whose iterated base-l digit sum takes exactly N steps to fall below l, and output it modulo m.	Hard8	Number theoryMath	No attempts yet	2s	512 MB	Judgeable
SkylandChoose nonnegative island heights totaling at least H to minimize linear plus pairwise absolute-difference costs, and report each minimum as a reduced fraction.	Hard8	GraphMath	No attempts yet	5s	64 MB	Judgeable
Tree AllocationPartition the nodes into blocks of at most B to minimize the worst root-to-leaf block count, for every choice of root.	Hard8	Dynamic programmingTree+1	No attempts yet	10s	64 MB	Judgeable
Balanced PathsCount ordered node pairs whose labels along the tree path form a balanced parenthesis string.	Hard8	Divide and conquerHash map+2	No attempts yet	3s	256 MB	Judgeable
Content DeliveryPick an item and destination for each of m deliveries on a weighted tree with path caching to maximize total size times travel distance.	Hard8	Dynamic programmingTree+1	No attempts yet	5s	256 MB	Judgeable
Cost Performance FlowFind an s-t flow minimizing squared cost plus squared shortfall from max flow in a capacitated graph with edge costs, and print the minimum as a fraction.	Hard8	GraphShortest path+1	No attempts yet	2s	256 MB	Judgeable
ICPC TeamsCount ways to split 3N students into teams of three so all M same-team and different-team pairs hold, modulo 1e9+9.	Hard8	CombinatoricsUnion-find+1	No attempts yet	3s	256 MB	Judgeable
MidpointCount the triples (i, j, k) from three collinear point sets in which C_k is the midpoint of A_i and B_j.	Hard8	GeometryMath+1	No attempts yet	10s	256 MB	Judgeable
Watering the fieldsCover every non-scarecrow cell with trominoes of three cells while letting at most R times C trominoes cross field borders.	Hard8	ImplementationBacktracking+1	No attempts yet	1s	128 MB	Judgeable
Distance on TriangulationAnswer the shortest path length along polygon sides and diagonals for many queried vertex pairs in a triangulated convex polygon.	Hard8	Divide and conquerShortest path+2	No attempts yet	2s	256 MB	Judgeable
HypercubeDecide whether a tree-like polycube of eight cubes folds along shared faces into the surface of a four-dimensional hypercube.	Hard8	BacktrackingGeometry	No attempts yet	1s	256 MB	Judgeable
JumpFind a hidden bit string of even length n using queries that reveal only whether the match count is 0, n/2, or n.	Hard8	ImplementationCombinatorics+1	No attempts yet	2s	512 MB	Judgeable
King's InspectionFind the lexicographically smallest directed tour that starts and ends at city 1 and visits every other city exactly once.	Hard8	GraphBacktracking+1	No attempts yet	10s	512 MB	Judgeable
Routing a Marathon RaceFind a simple path from junction 1 to junction n that minimizes the total personnel cost of the junctions on the path and their direct neighbors.	Hard8	BacktrackingGraph+2	No attempts yet	3s	256 MB	Judgeable
Post Office InvestigationGiven a directed delivery network from office 1, each query asks for the cheapest office that lies on every route to all listed complaint offices.	Hard8	GraphTree	No attempts yet	3s	256 MB	Judgeable
Min-Max Distance GameStarting from the given first player, both sides alternately remove one stone until two remain, with Alice maximizing and Bob minimizing the final distance.	Hard8	Game theoryGreedy+1	No attempts yet	1s	256 MB	Judgeable
Niya's HappinessTrack insertions and deletions in a banknote multiset and report after each update whether every amount up to the total is payable exactly.	Hard8	Segment treeSorting+1	No attempts yet	3s	512 MB	Judgeable
Queue of SoldiersCount distinct lineups of soldiers with given heights where exactly K soldiers have a strictly shorter soldier ahead of them.	Hard8	CombinatoricsDynamic programming+1	No attempts yet	5s	256 MB	Judgeable
Sunlight on a TreeReport all nodes on the tree path from u to v whose dot product with the query direction is minimal.	Hard8	TreeSegment tree+1	No attempts yet	5s	256 MB	Judgeable
Stop Making SenseFor each input point in turn, remove it and report the area of the smallest convex polygon enclosing the rest.	Hard8	GeometrySorting+1	No attempts yet	1s	256 MB	Judgeable
Connect the CellsConnect each color pair with disjoint grid paths that cover every cell and print the lexicographically smallest direction map.	Hard8	BacktrackingGraph+1	No attempts yet	3s	256 MB	Judgeable
Bike SharingChoose one shared station capacity and the highest-paying riders it allows to maximize fare revenue minus capacity cost.	Hard8	GraphBinary search	No attempts yet	10s	256 MB	Judgeable
High JumpReconstruct each height's clears and misses from the recorded attempt order and report the top three jumpers under the countback tiebreak.	Hard8	SimulationBacktracking	No attempts yet	1s	256 MB	Judgeable
New Year TrainAssign each wagon in input order to one of M queue tracks so wagons exit numbered 1 to N, choosing the lexicographically smallest assignment.	Hard8	GreedyQueue+1	No attempts yet	2s	256 MB	Judgeable
Mountain Trek RouteAdd at most k unit blocks onto circular steps to maximize the drop in total up-and-down height around the loop.	Hard8	GreedyHeap+1	No attempts yet	2s	64 MB	Judgeable
SubstringsOrder all given strings as the consecutive length-L windows of one string of length L+N-1 and print the lexicographically smallest such string.	Hard8	GraphDFS+2	No attempts yet	2s	256 MB	Judgeable
Special graphEdge deletions hit a functional graph while queries ask for the directed distance from a to b along the single outgoing walk.	Hard8	GraphTree+1	No attempts yet	1s	64 MB	Judgeable
Round wordsGiven two words of length up to 2000, pick a rotation or reversal of each to maximize the LCS length and print that maximum.	Hard8	Dynamic programmingString	No attempts yet	2s	128 MB	Judgeable
Longest Shortest Paths at ShymbulakCount every shortest path between all vertex pairs at the maximum distance in a connected graph with N vertices and N equal edges.	Hard8	GraphBFS+2	No attempts yet	2s	256 MB	Judgeable
Marriage questionsCount the candidate intervals [L, R] in which all M daughters can each marry a distinct candidate they accept.	Hard8	GraphTwo pointers	No attempts yet	2s	256 MB	Judgeable
RoadsEdges of a weighted tree are deleted in the given order, and after each deletion you report the diameters of the two resulting components in increasing order.	Hard8	Union-findTree	No attempts yet	5s	512 MB	Judgeable
Guessing GameIdentify a hidden integer from 1 to n with adaptive subset questions where each NO costs a and each YES costs b while minimizing the worst-case total.	Hard8	Dynamic programmingBinary search+1	No attempts yet	1s	256 MB	Judgeable
Rain AgainFind the fewest leading drops so every W by H rectangle inside the L by L pot contains a drop strictly inside, or report -1.	Hard8	Binary searchSegment tree+1	No attempts yet	2s	256 MB	Judgeable
Splitting NimDecide whether the first player wins a Nim variant where each turn removes stones from a pile or splits one pile into two.	Hard8	Game theoryMath	No attempts yet	2s	512 MB	Judgeable
Subsequence HashesPrint the polynomial hashes of the K lexicographically smallest non-empty subsequences of the given array.	Hard8	HeapSorting+1	No attempts yet	1s	256 MB	Judgeable
Birthday Numbers IIAdd up the products of every neighboring pair among the integers between x and y that use only the digits 3, 5 and 8, and report the total modulo 19980305.	Hard8	MathRecursion+2	No attempts yet	1s	256 MB	Judgeable
Edge DestructionCount the connected components left after deleting edges l through r for each of Q independent queries.	Hard8	GraphUnion-find+1	No attempts yet	3s	128 MB	Judgeable
Counting palindromesCount the palindromic substrings fully contained in each query interval of a lowercase string.	Hard8	String matchingSegment tree+2	No attempts yet	2s	64 MB	Judgeable
Find the missing rankCount score assignments within given ranges where no person receives rank R under tied ranking.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	2s	32 MB	Judgeable
Swapping the StonesMove stones along empty arcs of a circular shore so black and white stones exchange position sets with minimum total carry distance, or report impossibility.	Hard8	GreedyString matching+1	No attempts yet	2s	32 MB	Judgeable
CabinsFind the K-th smallest travel distance among all pairs of cabins placed on a weighted tree of river regions.	Hard8	Binary searchDivide and conquer+1	No attempts yet	6s	64 MB	Judgeable
GuardsCount the subsets of at least two applicants with pairwise coprime favorite numbers, modulo 1,000,000,007.	Hard8	Dynamic programmingNumber theory+1	No attempts yet	2s	32 MB	Judgeable
Connecting the wiresPlace each equal-number pair above or below a row so same-side joining arcs never cross, and print the lexicographically smallest side string.	Hard8	GraphDFS+2	No attempts yet	1s	64 MB	Judgeable
K-th smallest weight on a tree pathAnswer each query with the K-th smallest vertex weight on the path between two vertices in a tree.	Hard8	Segment treeTree+1	No attempts yet	1.5s	512 MB	Judgeable
Fortune Telling 2N two-sided cards start showing A_i and each threshold T_j flips every card whose visible number is at most T_j; compute the final visible sum.	Hard8	Segment treeSorting+1	No attempts yet	2s	256 MB	Judgeable
ShoppingChoose a right-and-down path from (1,1) to (H,W) that minimizes the price of visited and neighboring shops when one neighbor shop can be skipped at each step.	Hard8	Dynamic programmingShortest path	No attempts yet	2s	512 MB	Judgeable
Mowing the FieldCount interior crossings of perpendicular mower segments cut at least T days apart.	Hard8	Segment treeGeometry+1	No attempts yet	5s	512 MB	Judgeable
FaultGiven diagonal fault shifts with surface erosion, report the original depth of the layer exposed at each unit of the surface.	Hard8	Segment treeGeometry	No attempts yet	2s	256 MB	Judgeable
Alphabet Blocks and PasswordsArrange A to Z into the lexicographically smallest permutation with none of the given passwords appearing as a contiguous block.	Hard8	BacktrackingString matching+1	No attempts yet	5s	512 MB	Judgeable
Balloon RecoveryDistribute a shared energy budget across height changes so every balloon riding layered winds reaches position zero as early as possible.	Hard8	Binary searchDynamic programming	No attempts yet	5s	512 MB	Judgeable
Albocede DNA (Large)Count subsequences of S that split into one or more blocks of the form a^i b^j c^i d^j with i and j at least 1, modulo 1000000007.	Hard8	Dynamic programmingCombinatorics	No attempts yet	5s	512 MB	Judgeable
Tying All the CardsTie all N cards into one connected set where each tie costs the larger number modulo the smaller, with minimum total cost.	Hard8	Minimum spanning treeNumber theory+1	No attempts yet	5s	768 MB	Judgeable
Costly Binary Search (Large)Given the cost of comparing against each array position, find the smallest worst-case total cost of an adaptive binary search for the insertion point.	Hard8	Dynamic programmingDivide and conquer+1	No attempts yet	60s	1536 MB	Judgeable
Campground Arrangements (Large)Count N by N grids with entries 0 to 3 where each row and column sums to 3 with at most two tents and at least X threes, modulo 1e9+7.	Hard8	CombinatoricsMath	No attempts yet	5s	512 MB	Judgeable
Taking Over the World (Large)Obstruct up to K vertices to maximize the guards' travel time, then report the shortest path time from the entrance to the weapon room.	Hard8	Shortest pathGraph	No attempts yet	5s	512 MB	Judgeable
Merlin QA (Large)Cast every spell once in the order that leaves the most valuable leftovers, since free storehouse stock covers only inputs the current stock cannot.	Hard8	Dynamic programmingGreedy+1	No attempts yet	5s	512 MB	Judgeable
Fairland (Large)Keep the largest rooted connected subtree containing the CEO so all kept salaries fit within a range of width D.	Hard8	TreeSliding window+2	No attempts yet	10s	512 MB	Judgeable
Runaway QuailStarting at zero on a line, catch every quail that flees outward at a speed below yours in the smallest possible total time.	Hard8	Dynamic programmingMath+1	No attempts yet	5s	512 MB	Judgeable
Log Set (Large)Recover the original integer multiset from the frequency table of all its subset sums, breaking ties by lexicographic order.	Hard8	GreedySorting+1	No attempts yet	5s	512 MB	Judgeable
Drum Decorator (Small)Count cylindrical grid fillings where each cell holding K has exactly K equal neighbours, up to rotation, modulo 1e9+7.	Hard8	CombinatoricsDynamic programming+1	No attempts yet	5s	512 MB	Judgeable
Drum Decorator (Large)Count fillings of an R by C cylinder grid where each cell with value K has exactly K edge neighbors with value K, up to rotation, modulo 1000000007.	Hard8	CombinatoricsGraph+1	No attempts yet	5s	512 MB	Judgeable
Hiking DeerChoose speeds, including full stops, for one clockwise loop of a circular trail to minimize meetings with hikers who walk at constant speeds.	Hard8	MathSorting+1	No attempts yet	5s	512 MB	Judgeable
Hiking Deer (Large)Plan a variable-speed loop around a circular trail to cross paths with as few constant-speed hikers as possible.	Hard8	GreedyIntervals+1	No attempts yet	5s	512 MB	Judgeable
Googlander (Large)Count the distinct self-avoiding walks on an R by C grid that start at the bottom left facing up and at each step go straight or turn right.	Hard8	Dynamic programmingRecursion+1	No attempts yet	5s	512 MB	Judgeable
Power SwapperCount the ordered sequences of aligned block swaps, using each size at most once, that sort the given permutation.	Hard8	Divide and conquerRecursion+1	No attempts yet	5s	512 MB	Judgeable
ARAM (Large)Decide when to spend reroll currency on random champions to maximize the long-run win rate over many games.	Hard8	Dynamic programmingProbability+2	No attempts yet	120s	512 MB	Judgeable
Willow (Large)Two players pick starts on a coin tree and alternately take city coins while each used road closes for both, and the first player maximizes the score gap.	Hard8	Game theoryTree+1	No attempts yet	120s	512 MB	Judgeable
Don't Break the Nile (Large)Compute the maximum unit flow from the south edge to the north edge of a grid blocked by up to 1000 rectangles.	Hard8	Shortest pathGraph+1	No attempts yet	5s	512 MB	Judgeable
Trie ShardingSplit the strings among N labeled non-empty servers to maximize the total trie node count and report the maximum and the count of optimal splits modulo 1e9+7.	Hard8	Dynamic programmingTrie+1	No attempts yet	5s	512 MB	Judgeable
The Bored Traveling Salesman (Large)Visit every city in a connected graph using paired outbound and return flights so the ZIP codes in order of first visit form the smallest possible number.	Hard8	DFSGraph+1	No attempts yet	5s	512 MB	Judgeable
Hamiltonian pathPrint the lexicographically smallest path that visits every vertex once following directed edges, or -1 when it does not exist.	Hard8	GraphGreedy+1	No attempts yet	1s	512 MB	Judgeable
Let Me Tell You a Story (Large)Count the orders in which ministers can be fired while a salary complaint remains possible until the survivors are non-increasing, modulo 10007.	Hard8	CombinatoricsDynamic programming	No attempts yet	30s	512 MB	Judgeable
Observation Wheel (Large)Compute the expected total fare collected as visitors starting at uniform random gondolas fill all free spots on a circular wheel.	Hard8	ProbabilityDynamic programming+1	No attempts yet	5s	512 MB	Judgeable
Ticket SwappingPassengers riding one direction on a line pay a decreasing per-stop fare and may swap entry cards where trips overlap, so compute the maximum total fare loss.	Hard8	GreedySorting+2	No attempts yet	5s	512 MB	Judgeable
Many prizesIn a Swiss tournament of 2^N teams where the lower number always wins, find the largest team ranked top P under every seeding and under some seeding.	Hard8	CombinatoricsMath+1	No attempts yet	5s	512 MB	Judgeable
Multiplayer Pong (Large)Two teams alternately return a reflecting ball in fixed order, and the team whose player misses loses, so decide the winner and the loser return count.	Hard8	MathGame theory+1	No attempts yet	5s	512 MB	Judgeable
The Great Wall (Large)Count how many moving interval attacks pierce a wall that rises after each success to the strength that would have stopped it.	Hard8	Segment treeIntervals+1	No attempts yet	15s	512 MB	Judgeable
Falling Diamonds (Large)N diamonds drop onto x=0 and slide left or right at random, and each query asks the probability that a diamond rests exactly at (X, Y).	Hard8	ProbabilitySimulation+1	No attempts yet	5s	512 MB	Judgeable
Fair and Square (Large2)Count numbers in each interval [A, B] that read the same forwards and backwards and equal the square of such a number.	Hard8	MathString+1	No attempts yet	5s	512 MB	Judgeable
Upstairs and DownstairsKonstantin chooses and orders at least K activities from limited copies to minimize the chance Ilia wakes after falling asleep.	Hard8	ProbabilityDynamic programming+2	No attempts yet	5s	512 MB	Judgeable
Upstairs and DownstairsKonstantin must order at least K activities with capped repeats to minimize the chance Ilia falls asleep and later wakes.	Hard8	ProbabilityGreedy+1	No attempts yet	100s	512 MB	Judgeable
Xeno-archaeology (Large)From tile positions and colors in infinite alternating square rings, find the fitting center nearest the origin or report the tiles as too damaged.	Hard8	MathGeometry+1	No attempts yet	5s	512 MB	Judgeable
Lost PasswordGiven k = 2 and a string S, find the length of the shortest string containing every l33tspeak variant of each length-1 and length-2 substring of S.	Hard8	GraphShortest path+1	No attempts yet	5s	512 MB	Judgeable
The peak that looks highestGiven each peak's apparent-highest peak ahead, assign integer heights matching all sightings and print the lexicographically smallest heights or Impossible.	Hard8	GeometryBacktracking+1	No attempts yet	5s	512 MB	Judgeable
Descending in the Dark (Large)For each cave in a grid with left, right, and down moves, count the squares that can reach it and decide if one shared move list brings all of them to it.	Hard8	GraphBFS	No attempts yet	40s	512 MB	Judgeable
Tide Goes In, Tide Goes Out (Large)Given a grid of cave floor and ceiling heights and a receding tide, find the fastest route to the exit where moves open and slow down as the water falls.	Hard8	Shortest pathBinary search+2	No attempts yet	5s	512 MB	Judgeable
Hall of MirrorsCount the directions from the center of a mirrored grid room in which a ray returns to the viewer within distance D under the given reflection rules.	Hard8	GeometrySimulation	No attempts yet	5s	512 MB	Judgeable
Hall of Mirrors (Large)Count the directions in which a ray from your cell returns to its exact center after mirror reflections within distance D.	Hard8	GeometrySimulation+1	No attempts yet	5s	512 MB	Judgeable
Commute War (Large)Choose connecting services to minimize expected travel time when departures leave hourly and each ride faces repeated random inspection delays.	Hard8	Shortest pathProbability+1	No attempts yet	5s	512 MB	Judgeable
Yut Nori (Large)You receive every throw in order and the pieces left on the board, and you decide whether the game rules can produce that board.	Hard8	BacktrackingSimulation+1	No attempts yet	10s	512 MB	Judgeable
Houses on the Han RiverCount the integers below N that have as many divisors as N and whose smallest prime factor is at least M.	Hard8	Number theoryCombinatorics	No attempts yet	5s	512 MB	Judgeable
Wildcard (Large)Given two filenames A and B, find the shortest star pattern that matches A but not B, breaking ties by fewer stars then lexicographic order.	Hard8	Dynamic programmingString matching+1	No attempts yet	5s	512 MB	Judgeable
Closet Room (Large)Place the maximum number of 2-cell closets, each needing an empty door tile, on a grid with pillars so every door tile stays connected to the entrance.	Hard8	Dynamic programmingGraph+1	No attempts yet	5s	512 MB	Judgeable