Problems

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Total results29,417 problems

The j-th Number
Hard8
Binary search, Segment tree+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Tree Reconstruction
Hard8
Graph, Union-find+1
No attempts yet
Time limit
10s
Memory limit
128 MB
Judgeable
Fallen Apples and the Nearest Tree
Hard8
Geometry, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Stack Maze
Hard8
Dynamic programming, Stack+1
No attempts yet
Time limit
8s
Memory limit
256 MB
Judgeable
Counting 1's
Hard8
Bit manipulation, Math
No attempts yet
Time limit
8s
Memory limit
256 MB
Judgeable
Magical Bridges
Hard8
Shortest path, Math
No attempts yet
Time limit
8s
Memory limit
256 MB
Judgeable
Ancient Scrolls
Hard8
Greedy, String+1
No attempts yet
Time limit
8s
Memory limit
256 MB
Judgeable
Everlasting -One-
Hard8
Graph, Combinatorics+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Putter
Hard8
Geometry, Brute force
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Floating Islands
Hard8
Dynamic programming, Minimum spanning tree+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Magical Switches
Hard8
Graph, DFS+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Exact Longest Monotone Subsequence
Hard8
Combinatorics, Greedy+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Revenge of the ants 2
Hard8
String matching, Sorting+2
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Pangaea 2
Hard8
Minimum spanning tree, Tree
No attempts yet
Time limit
20s
Memory limit
256 MB
Judgeable
The Light King and the Mirror Maze 2
Hard8
Dynamic programming, Graph+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Rooks and Marbles
Hard8
Graph
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Slave to Achievements 3
Hard8
Probability, Dynamic programming+2
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Fire Truck Dispatch
Hard8
Shortest path, Geometry+1
No attempts yet
Time limit
15s
Memory limit
256 MB
Judgeable
Fencing the Herd
Hard8
Geometry, Binary search
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Editor
Hard8
Stack, Segment tree+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
File Paths
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Hacker
Hard8
Game theory, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Asteroids
Hard8
Geometry, Math
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Evolution in Parallel
Hard8
Graph, BFS+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Measuring the Running Speed
Hard8
Binary search, Math+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Qanat
Hard8
Math, Binary search
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Tours
Hard8
Graph, DFS+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Queen Bee
Hard8
Dynamic programming, Simulation+1
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Bali Sculptures
Hard8
Dynamic programming, Greedy+1
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Jakarta Skyscrapers
Hard8
Shortest path, Graph+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Turning off the bulbs
Hard8
Combinatorics, Two pointers+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Interactive Interception
Hard8
Math, Binary search+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Which intersections did I pass?
Hard8
Graph, DFS+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
One Clean Slice!
Hard8
Backtracking, Binary search+1
No attempts yet
Time limit
1s
Memory limit
16 MB
Judgeable
Hexagon travel
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
32 MB
Judgeable
Make a superpalindrome
Hard8
String, Recursion+1
No attempts yet
Time limit
1s
Memory limit
16 MB
Judgeable
Actually visible points
Hard8
Number theory, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Maximize the matrix sum
Hard8
Math, Greedy+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
The last wizard
Hard8
Probability, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Xtreme gcd sum
Hard8
Number theory, Math
No attempts yet
Time limit
4s
Memory limit
256 MB
Judgeable
Scales
Hard8
Sorting, Implementation+1
No attempts yet
Time limit
1s
Memory limit
1536 MB
Judgeable
Forming Teams
Hard8
Greedy, Intervals+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Selling horses
Hard8
Segment tree, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sorting 2
Hard8
BFS, Shortest path+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Nuclearia
Hard8
Prefix sum, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Wouldn't it be better to just earn garnets?
Hard8
Shortest path, Dynamic programming
No attempts yet
Time limit
10s
Memory limit
128 MB
Judgeable
Crow
Hard8
Geometry, Shortest path+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Exchange
Hard8
Segment tree, Sorting+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Last eight digits of a power tower
Hard8
Number theory, Math+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Complex Paper Folding
Hard8
Geometry, Brute force
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Reducing Network Diameter
Hard8
Greedy, Tree+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Who Do You Think You Are?
Hard8
Graph, Tree+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Selling Numbers
Hard8
Backtracking, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Tree of Pain
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Proud Penguin
Hard8
Binary search, Greedy+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Troublesome Tools
Hard8
Combinatorics, Math
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Birthday Party
Hard8
Combinatorics, Probability+1
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Dad's Card Trick
Hard8
Math, Combinatorics
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Absurdistan Roads II
Hard8
Combinatorics, Probability+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Xortris
Hard8
Math, Combinatorics
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Shibuya Crossing
Hard8
Graph, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Area of Effect
Hard8
Geometry, Brute force
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Extensive Or
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Primal Partitions
Hard8
Binary search, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Sand Art
Hard8
Graph, Binary search
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Marble Madness
Hard8
Dynamic programming, Math+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Hive
Hard8
Graph, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
iCar
Hard8
Shortest path, Math
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Just a Quiz
Hard8
Dynamic programming, Trie+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
2-SAT smallest assignment
Hard8
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Train of Threes
Hard8
Dynamic programming, Intervals
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Bracket Strings
Hard8
Combinatorics, Number theory+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Stacked Colored Paper
Hard8
Geometry, Math
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Ants in a Corridor
Hard8
Math, Sorting
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Fibonomial
Hard8
Number theory, Math
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Finding a Grayscale Image
Hard8
String matching, Matrix+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Splitting into Primes
Hard8
Probability, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Feeding the Herrings
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Visitors' Train
Hard8
Geometry, Intervals
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Maximum lexicographically minimal topological sort
Hard8
Topological sort, Greedy+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Kingdom Trip
Hard8
Dynamic programming, Geometry
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Call a Cab
Hard8
Dynamic programming, Segment tree+2
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Zeroing the Grid
Hard8
Graph
No attempts yet
Time limit
7s
Memory limit
256 MB
Judgeable
Path Inside a Histogram
Hard8
Geometry, Shortest path
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Polynomial
Hard8
Math, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Colored painting sales
Hard8
Dynamic programming, Segment tree+1
No attempts yet
Time limit
4s
Memory limit
32 MB
Judgeable
Party joke sets
Hard8
Dynamic programming, Tree+1
No attempts yet
Time limit
1s
Memory limit
32 MB
Judgeable
Mosaic
Hard8
Backtracking, Brute force
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Just a bit sorted
Hard8
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Pyramid Base
Hard8
Binary search, Geometry+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Seonjin's Frozen Kingdom
Hard8
DFS, Graph
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Butterfly Effect
Hard8
Dynamic programming, Probability
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Olympics
Hard8
Dynamic programming, Math
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Book Borders
Hard8
Divide and conquer, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cow Confinement
Hard8
Segment tree, Sorting+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Export Estimate
Hard8
Graph, Union-find+1
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Frightful Formula
Hard8
Combinatorics, Math
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Greenhouse Growth
Hard8
Segment tree, Stack+2
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Juice Junctions
Hard8
Graph, Tree+2
No attempts yet
Time limit
7s
Memory limit
512 MB
Judgeable
Kernel Knights
Hard8
Graph, Greedy
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
The j-th NumberAfter copying each insert value into every array of its interval, each query asks for the j-th smallest value collected from an interval of arrays.	Hard8	Binary searchSegment tree+2	No attempts yet	10s	512 MB	Judgeable
Tree ReconstructionGiven a directed graph with strongly connected components, find the smallest edge set whose values fix all remaining flows by conservation.	Hard8	GraphUnion-find+1	No attempts yet	10s	128 MB	Judgeable
Fallen Apples and the Nearest TreeFor each yearly apple drop on a grid, output the squared Euclidean distance to the nearest existing tree, counting the new tree only from the next year.	Hard8	GeometryDynamic programming+2	No attempts yet	2s	128 MB	Judgeable
Stack MazeYou move only right or down through the grid, pick up lettered jewels, and drop them into matching holes in last-in-first-out order for the most matches.	Hard8	Dynamic programmingStack+1	No attempts yet	8s	256 MB	Judgeable
Counting 1'sGiven how many numbers in the hidden interval [A, B] have each binary bit set, recover A and B or report Many or None.	Hard8	Bit manipulationMath	No attempts yet	8s	256 MB	Judgeable
Magical BridgesChoose one shared length for all magical bridges so the shortest routes from two starts to the target differ as little as possible.	Hard8	Shortest pathMath	No attempts yet	8s	256 MB	Judgeable
Ancient ScrollsRecover the lexicographically smallest string within Hamming distance d of three given strings, or print -1 when no such string exists.	Hard8	GreedyString+1	No attempts yet	8s	256 MB	Judgeable
Everlasting -One-Count how the 2^N light-darkness sets split into groups linked by job changes between disjoint sets that share a connected pair, modulo 1e9+7.	Hard8	GraphCombinatorics+1	No attempts yet	8s	512 MB	Judgeable
PutterCount the orders in which a single bouncing shot from inside a convex polygon can hit each wall exactly once.	Hard8	GeometryBrute force	No attempts yet	8s	512 MB	Judgeable
Floating IslandsFind the cheapest connected bridge network where each bridge costs the position difference and each island has a degree limit, or report -1 when impossible.	Hard8	Dynamic programmingMinimum spanning tree+1	No attempts yet	8s	512 MB	Judgeable
Magical SwitchesChoose which of the 26 color switches to push so a token can walk from the left edge to the right edge of a 3-row board.	Hard8	GraphDFS+1	No attempts yet	8s	512 MB	Judgeable
Exact Longest Monotone SubsequenceBuild the lexicographically smallest permutation of 1 to N whose longest increasing or decreasing subsequence has length exactly K, or print -1 when impossible.	Hard8	CombinatoricsGreedy+1	No attempts yet	1s	256 MB	Judgeable
Revenge of the ants 2Labeled ants walk both ways on a circular rail and bounce on collision; compute when each ant is back at its start with its initial direction.	Hard8	String matchingSorting+2	No attempts yet	5s	256 MB	Judgeable
Pangaea 2Starting from a given tree, each added road updates the minimum total length that keeps all cities connected, and each test case outputs the XOR of the answers.	Hard8	Minimum spanning treeTree	No attempts yet	20s	256 MB	Judgeable
The Light King and the Mirror Maze 2Count the ways to fill each ? with /, \ or empty on an N by M board so the beam entering border port x leaves at port y, modulo 10007.	Hard8	Dynamic programmingGraph+1	No attempts yet	2s	256 MB	Judgeable
Rooks and MarblesPlace as many marbles as digit caps allow so every rook counts the same total along its row range and its column range.	Hard8	Graph	No attempts yet	3s	256 MB	Judgeable
Slave to Achievements 3Starting from M scraps, repeated crafting and dismantling ends with fewer than N scraps, and you must report each final remainder probability modulo 1e9+7.	Hard8	ProbabilityDynamic programming+2	No attempts yet	3s	256 MB	Judgeable
Fire Truck DispatchFind the shortest drive along roads from any station to a point within hose radius R of each fire, printing -1 when no such point can be reached.	Hard8	Shortest pathGeometry+1	No attempts yet	15s	256 MB	Judgeable
Fencing the HerdThe herd grows over time and each query asks whether every cow so far lies strictly on one side of the given line.	Hard8	GeometryBinary search	No attempts yet	2s	256 MB	Judgeable
EditorGiven up to 500000 edits and leveled undos, print the editor state after each operation.	Hard8	StackSegment tree+1	No attempts yet	3s	512 MB	Judgeable
File PathsDecide for each file whether one directory shortcut of fixed name length can create a path of exactly k characters to it.	Hard8	GraphShortest path+2	No attempts yet	1s	256 MB	Judgeable
HackerChoose a start on a valued ring and spread to neighboring computers each turn to maximize hacked value against an optimal blocker.	Hard8	Game theoryDynamic programming+1	No attempts yet	1s	256 MB	Judgeable
AsteroidsFind the positive time when two steadily moving convex polygons share their largest overlap area, or report the first touch or never.	Hard8	GeometryMath	No attempts yet	2s	256 MB	Judgeable
Evolution in ParallelDecide whether every fossil sequence fits into one of two chains in which each sequence is a subsequence of the next one and of the living species sequence.	Hard8	GraphBFS+1	No attempts yet	2s	256 MB	Judgeable
Measuring the Running SpeedMinhyeok picks timed yes-or-no position checks to shrink Yura's possible speed range to width t with the fewest checks in the worst case.	Hard8	Binary searchMath+1	No attempts yet	2s	256 MB	Judgeable
QanatPlace n extra vertical shafts above a horizontal channel to minimize the total dirt removal cost and print the cost with the shaft positions.	Hard8	MathBinary search	No attempts yet	2s	256 MB	Judgeable
ToursFind every k for which roads can go to k companies so each cycle contains the same number of roads of each company.	Hard8	GraphDFS+1	No attempts yet	3s	256 MB	Judgeable
Queen BeeEach day border cells grow by given amounts and each inner cell copies one of three neighbors by its rule table, and you report every cell size after N days.	Hard8	Dynamic programmingSimulation+1	No attempts yet	5s	256 MB	Judgeable
Bali SculpturesSplit N sculptures in order into between A and B consecutive groups to minimize the bitwise OR of the group age sums.	Hard8	Dynamic programmingGreedy+1	No attempts yet	1s	64 MB	Judgeable
Jakarta SkyscrapersDoge 0 spreads news by jumping between buildings with its own stride or handing it to a doge on the same building, and you count the fewest jumps to doge 1.	Hard8	Shortest pathGraph+1	No attempts yet	1s	256 MB	Judgeable
Turning off the bulbsCount the possible turn-off orders when an interval expands from a start bulb by always taking the stronger of the two frontier bulbs, branching on ties.	Hard8	CombinatoricsTwo pointers+1	No attempts yet	1s	512 MB	Judgeable
Interactive InterceptionFind an unknown start position in 0 to p and unknown speed in 0 to v of a moving point using at most 100 range queries, which are answered on the moving point's position each second.	Hard8	MathBinary search+1	No attempts yet	2s	512 MB	Judgeable
Which intersections did I pass?Given a connected undirected graph, each query asks how many vertices lie on some walk from a to b that never revisits the endpoints in the middle.	Hard8	GraphDFS+1	No attempts yet	2s	256 MB	Judgeable
One Clean Slice!Split an R by C by H block with guillotine cuts into N boxes with one raisin each to maximize the smallest box volume.	Hard8	BacktrackingBinary search+1	No attempts yet	1s	16 MB	Judgeable
Hexagon travelCount the orders of L left turns, R right turns and M moves that leave a hex-grid robot on a red, green, or blue tile, modulo 1,000,000,007.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	2s	32 MB	Judgeable
Make a superpalindromeGiven a lowercase string, find the smallest superpalindrome of the same length that comes after it in lexicographic order.	Hard8	StringRecursion+1	No attempts yet	1s	16 MB	Judgeable
Actually visible pointsCount the nondecreasing integer chains ending at the given values with no other chain point on the segment from the origin, modulo 1000000007.	Hard8	Number theoryCombinatorics+1	No attempts yet	1s	256 MB	Judgeable
Maximize the matrix sumReorder entries by rotating rows and columns and flipping row and column signs to maximize the sum of all cells.	Hard8	MathGreedy+2	No attempts yet	2s	256 MB	Judgeable
The last wizardTen counters start at 1 and grow through T random additive updates; output their expected product scaled by A to the T modulo 1000000007.	Hard8	ProbabilityCombinatorics+2	No attempts yet	1s	256 MB	Judgeable
Xtreme gcd sumAdd the gcd of every tuple formed by picking one integer from each of the n given intervals and print the total modulo 1,000,000,007.	Hard8	Number theoryMath	No attempts yet	4s	256 MB	Judgeable
ScalesOrder six coins by weight using a four-pan scale whose four query types report the heaviest, lightest, or median coin among three pans, or the lightest coin heavier than the fourth pan's coin.	Hard8	SortingImplementation+1	No attempts yet	1s	1536 MB	Judgeable
Forming TeamsFor each planned day, decide whether students with accepted size ranges can fill all requested teams of the given sizes.	Hard8	GreedyIntervals+2	No attempts yet	4s	512 MB	Judgeable
Selling horsesOne horse multiplies by X[i] each year and any held horses sell at price Y[i]; report the maximum revenue after each point update modulo 1e9+7.	Hard8	Segment treeGreedy+1	No attempts yet	2s	512 MB	Judgeable
Sorting 2Choose one swap per round after the fixed rival swap to sort the permutation in the fewest rounds, with the lexicographically smallest choice list on ties.	Hard8	BFSShortest path+1	No attempts yet	1s	512 MB	Judgeable
NucleariaAdd up the linearly decaying king-move radiation from every plant in each grid cell, then answer each rectangle query with its rounded average.	Hard8	Prefix sumMath	No attempts yet	1s	1024 MB	Judgeable
Wouldn't it be better to just earn garnets?Find the second-fastest travel time from island 1 to island N over walks that may repeat bridges, and the largest garnet total among walks with that time.	Hard8	Shortest pathDynamic programming	No attempts yet	10s	128 MB	Judgeable
CrowSum the shortest path lengths between consecutive query points that stay above the ground and outside a polygonal mountain.	Hard8	GeometryShortest path+1	No attempts yet	3s	256 MB	Judgeable
ExchangeCount the swaps performed by running the first M passes of selection sort on each array.	Hard8	Segment treeSorting+1	No attempts yet	1s	256 MB	Judgeable
Last eight digits of a power towerGiven a and b, print the last eight digits of the b-level power tower of a, keeping leading zeros for large values.	Hard8	Number theoryMath+1	No attempts yet	1s	256 MB	Judgeable
Complex Paper FoldingTry every vertex-to-vertex fold of a convex polygon and report the perimeter of the result with the most vertices.	Hard8	GeometryBrute force	No attempts yet	1s	256 MB	Judgeable
Reducing Network DiameterPay per unit of reduction on tree edge weights so the longest path between any two nodes is at most D at minimum total cost.	Hard8	GreedyTree+2	No attempts yet	2s	256 MB	Judgeable
Who Do You Think You Are?Read a family tree and answer queries naming the relationship of name1 to name2, including blood, cousin, and in-law terms.	Hard8	GraphTree+2	No attempts yet	2s	256 MB	Judgeable
Selling NumbersCount how many D-digit strings, with leading zeros allowed, have exactly the memorability score S defined by palindromic and repeated substrings.	Hard8	BacktrackingCombinatorics+1	No attempts yet	2s	256 MB	Judgeable
Tree of PainDecide for each small pattern tree whether it embeds into the organization tree with matching labels and ancestry preserved both ways.	Hard8	TreeDynamic programming+2	No attempts yet	1s	256 MB	Judgeable
Proud PenguinDistribute at most W units of water into level pools along a polygonal track to minimize the tallest uphill stretch penguins must climb.	Hard8	Binary searchGreedy+1	No attempts yet	3s	256 MB	Judgeable
Troublesome ToolsCount the worst-case number of tool sets Inco tries when each request is known only by its size and repeated names.	Hard8	CombinatoricsMath	No attempts yet	2s	256 MB	Judgeable
Birthday PartyEach of N guests gives a present to a random other guest, and you must compute the probability that some k guests form a directed gift cycle.	Hard8	CombinatoricsProbability+1	No attempts yet	5s	256 MB	Judgeable
Dad's Card TrickFor each test case with N cards and K face up, compute the fewest moves and flips that force both decks to hold equal face-up counts whatever the layout.	Hard8	MathCombinatorics	No attempts yet	1s	256 MB	Judgeable
Absurdistan Roads IIN cities each build a road to one random other city; compute the probability that the N roads connect all cities.	Hard8	CombinatoricsProbability+2	No attempts yet	1s	256 MB	Judgeable
XortrisDecide whether the black cells of a board of up to 100 by 100 cells can all be turned white by repeatedly flipping four cells covered by a tetromino.	Hard8	MathCombinatorics	No attempts yet	1s	256 MB	Judgeable
Shibuya CrossingGiven the list of crossing path pairs, find the size of the largest group of people whose paths all cross each other.	Hard8	GraphDynamic programming+1	No attempts yet	1s	256 MB	Judgeable
Area of EffectPick a circle of radius at most r that avoids the interiors of the village circles and covers as many minion points as possible.	Hard8	GeometryBrute force	No attempts yet	5s	256 MB	Judgeable
Extensive OrCount n-element subsets of numbers below the huge binary bound formed by repeating s k times whose xor is zero, modulo 1e9+7.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	3s	256 MB	Judgeable
Primal PartitionsSplit the array into k consecutive segments to maximize the smallest segment score, where each segment scores its largest common prime factor or zero.	Hard8	Binary searchDynamic programming+1	No attempts yet	2s	256 MB	Judgeable
Sand ArtSplit m colored sand supplies across n box sections within per-section per-color limits to minimize the gap between the tallest and shortest heights.	Hard8	GraphBinary search	No attempts yet	3s	256 MB	Judgeable
Marble MadnessMove marbles between adjacent bins to maximize the total absolute difference of neighbor counts, and report that maximum plus the fewest moves achieving it.	Hard8	Dynamic programmingMath+1	No attempts yet	1s	256 MB	Judgeable
HiveEach rabbit walks a right-or-down path from the top-left cell to the bottom-right cell, and the goal is the fewest paths covering every flower.	Hard8	GraphCombinatorics+2	No attempts yet	1s	256 MB	Judgeable
iCarMinimize driving time over n kilometers of periodic traffic lights where the car accelerates from rest and every stop resets its speed to zero.	Hard8	Shortest pathMath	No attempts yet	1s	256 MB	Judgeable
Just a QuizTeresa interrupts randomly drawn known questions at chosen words to maximize expected correct answers within t seconds.	Hard8	Dynamic programmingTrie+1	No attempts yet	1s	256 MB	Judgeable
2-SAT smallest assignmentDecide whether a 2-CNF formula over up to 10000 variables is satisfiable and output the lexicographically smallest satisfying assignment.	Hard8	GraphDFS+2	No attempts yet	1s	256 MB	Judgeable
Train of ThreesYou repeatedly merge adjacent matching pairs in an array of 1s, 2s and numbers of the form 3 times a power of two to form the largest tile possible.	Hard8	Dynamic programmingIntervals	No attempts yet	5s	256 MB	Judgeable
Bracket StringsFor each queried length L, count bracket strings that match the incorrect or aperiodic filters chosen by flags p and q, modulo m.	Hard8	CombinatoricsNumber theory+2	No attempts yet	10s	512 MB	Judgeable
Stacked Colored PaperAfter gluing up to 200 triangles and circles in order, print each sheet's visible area after every prefix of the stack.	Hard8	GeometryMath	No attempts yet	1s	512 MB	Judgeable
Ants in a CorridorAnts join a corridor over time and bounce off each other and both walls, and each query asks for the position of one numbered ant.	Hard8	MathSorting	No attempts yet	3s	512 MB	Judgeable
FibonomialCount the exponent of each integer k from 2 to p in the product of the first n Fibonacci numbers.	Hard8	Number theoryMath	No attempts yet	2s	512 MB	Judgeable
Finding a Grayscale ImageCount the R by C windows of A that equal B after a linear brightness change of the form p times A plus q.	Hard8	String matchingMatrix+1	No attempts yet	10s	512 MB	Judgeable
Splitting into PrimesStarting from N, repeatedly split every composite into a random divisor pair and report the expected number of rounds until all parts are prime.	Hard8	ProbabilityDynamic programming+2	No attempts yet	1s	256 MB	Judgeable
Feeding the HerringsCount ordered triples summing to N with each part at least L and no digit 3 in any part, modulo 12345647.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	5s	256 MB	Judgeable
Visitors' TrainCompute the total length of a straight track segment from which the main rectangle stays fully visible behind other rectangles.	Hard8	GeometryIntervals	No attempts yet	1s	256 MB	Judgeable
Maximum lexicographically minimal topological sortAdd at most k edges to a DAG so its smallest topological order is as large as possible, then print that order and the fewest edges that force it.	Hard8	Topological sortGreedy+1	No attempts yet	2s	256 MB	Judgeable
Kingdom TripFind the shortest subsequence from the first to the last point so every skipped point lies within distance d of its shortcut segment.	Hard8	Dynamic programmingGeometry	No attempts yet	2s	256 MB	Judgeable
Call a CabPartition the ordered points into the fewest rides where each ride meets one type's minimum total distance and heading range limit.	Hard8	Dynamic programmingSegment tree+2	No attempts yet	5s	256 MB	Judgeable
Zeroing the GridFind the fewest operations that zero the grid when each operation decrements two orthogonally adjacent cells by 1.	Hard8	Graph	No attempts yet	7s	256 MB	Judgeable
Path Inside a HistogramCompute the sum of shortest inside-polygon distances from the base vertex to many boundary points in a rectilinear histogram.	Hard8	GeometryShortest path	No attempts yet	2s	256 MB	Judgeable
PolynomialGiven an integer polynomial of degree at most 25, find the reduced fractional coefficients of its sum from 0 to n and output the sum of the absolute numerators.	Hard8	MathCombinatorics+1	No attempts yet	1s	256 MB	Judgeable
Colored painting salesEach client buys a_i colored or b_i black-and-white paintings, and after each update count the sales with at least C colored buyers modulo 10007.	Hard8	Dynamic programmingSegment tree+1	No attempts yet	4s	32 MB	Judgeable
Party joke setsCount distinct joke-type sets from root-connected guest groups with unique values where each subtree below a guest forms consecutive numbers.	Hard8	Dynamic programmingTree+1	No attempts yet	1s	32 MB	Judgeable
MosaicFill empty grid cells with black right triangles so white regions form rectangles and numbered squares meet their counts, then report the triangle total.	Hard8	BacktrackingBrute force	No attempts yet	1s	256 MB	Judgeable
Just a bit sortedFor each query bound K, count length-N lists with values 1 to K where each value above 1 has its predecessor before its last occurrence.	Hard8	CombinatoricsDynamic programming+1	No attempts yet	3s	256 MB	Judgeable
Pyramid BaseFind the side length of the largest axis-aligned square on a grid that avoids all given rectangular obstacles.	Hard8	Binary searchGeometry+2	No attempts yet	5s	128 MB	Judgeable
Seonjin's Frozen KingdomDecide whether a walk on a grid that breaks each cell it leaves can visit the hatch cell, leave it, and step back onto it.	Hard8	DFSGraph	No attempts yet	2s	256 MB	Judgeable
Butterfly EffectDecide adaptively where to spend up to k double-die rolls across n chained chance events to maximize the chance the last event ends positive.	Hard8	Dynamic programmingProbability	No attempts yet	5s	256 MB	Judgeable
OlympicsWith each successful or failed lift draining energy, guarantee a successful lift within d of an unknown strength from 25 to 225 kg and minimize d.	Hard8	Dynamic programmingMath	No attempts yet	2s	256 MB	Judgeable
Book BordersFor each width m from a to b, wrap the words greedily into lines of at most m characters and report the length of the sentence made of each line's first word.	Hard8	Divide and conquerPrefix sum+1	No attempts yet	2s	512 MB	Judgeable
Cow ConfinementEach cow moves only down or right across a large grid and cannot cross rectangular fences, and the task asks how many flowers each cow can reach.	Hard8	Segment treeSorting+1	No attempts yet	10s	512 MB	Judgeable
Export EstimateFor each threshold query, count the vertices and edges left after deleting low-priority streets and contracting degree-two vertices in index order.	Hard8	GraphUnion-find+1	No attempts yet	4s	512 MB	Judgeable
Frightful FormulaCompute the bottom-right cell of an n by n matrix built from its first row and column with a linear recurrence, modulo 1000003.	Hard8	CombinatoricsMath	No attempts yet	10s	512 MB	Judgeable
Greenhouse GrowthGiven n sunflower heights and an m-day schedule of left or right lamps, compute every height after daily growth toward the taller neighbor.	Hard8	Segment treeStack+2	No attempts yet	6s	512 MB	Judgeable
Juice JunctionsAdd up the maximum unit-capacity flow between every pair of junctions in a graph where each junction joins at most three pipes.	Hard8	GraphTree+2	No attempts yet	7s	512 MB	Judgeable
Kernel KnightsFind the lexicographically smallest kernel among 2n knights where each knight challenges exactly one knight of the other house.	Hard8	GraphGreedy	No attempts yet	2s	512 MB	Judgeable