Math and counting

Number theory, combinatorics, and geometry

Under construction

Still being built. Things may change

Total results13,153 problems

Balanced Binary String
Hard8
String, Combinatorics+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Knocking Down
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Coins
Hard8
Math, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cakes
Hard8
Binary search, Greedy+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Partial Sums
Hard8
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Format a Table
Hard8
Brute force, Math+1
No attempts yet
Time limit
5s
Memory limit
64 MB
Judgeable
Game with Dominoes
Hard8
Game theory, Sorting+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Everyone Loves Playing Games
Hard8
Game theory, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Yet Another Geometry Problem
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
4s
Memory limit
256 MB
Judgeable
A Math Problem
Hard8
Math, Combinatorics
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Security System
Hard8
Geometry, Greedy+1
No attempts yet
Time limit
0.8s
Memory limit
1024 MB
Judgeable
Distance in Crosses
Hard8
Math, Geometry+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Galactic Governments
Hard8
Backtracking, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Multiplication
Hard8
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Structure Alignment
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Level check
Hard8
Graph, BFS+2
No attempts yet
Time limit
4s
Memory limit
256 MB
Judgeable
Intersection Graph
Hard8
Geometry, Implementation+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Tower Defense
Hard8
Tree, Divide and conquer+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
String Product
Hard8
String, Math+2
No attempts yet
Time limit
4s
Memory limit
256 MB
Judgeable
Fence
Hard8
Probability, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Algorithm Was Applied
Hard8
Graph, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Equal Adjacent Elements
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Formally, You Choose Three Integers
Hard8
Math, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hypercube
Hard8
Bit manipulation, Tree+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Edges Counting
Hard8
Combinatorics, Math+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Equanimous
Hard8
Dynamic programming, Math
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Three Dimensions
Hard8
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Cyclic Shift and Minimal Inversions
Hard8
Array, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Filipp Rukhovich
Hard8
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Time is Money
Hard8
Shortest path, Graph+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Two Dots
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Vertex Merge Game
Hard8
Graph, Greedy+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Rock Paper Scissors Strategy
Hard8
Implementation, Brute force+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Polygon Area
Hard8
Geometry, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Dyson Circle
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Flatland Olympics
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Burizon Fort
Hard8
Number theory, Math+2
No attempts yet
Time limit
1.4s
Memory limit
1024 MB
Judgeable
Screamers in the Storm
Hard8
Dynamic programming, Math+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Valid Parenthesis String
Hard8
Segment tree, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sequence (Hard)
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Jegi Kicking
Hard8
Binary search, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
F1ow3rC0n
Hard8
Segment tree, Array+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Bazza and Shazza
Hard8
Segment tree, Dynamic programming+2
No attempts yet
Time limit
13s
Memory limit
230 MB
Judgeable
Bookshelf Sorting
Hard8
Array, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Garbage Robot
Hard8
Simulation, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
HILO
Hard8
Combinatorics, Math+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Composite Function and Queries 2
Hard8
Graph, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Painters' Duel
Hard8
Game theory, Graph+1
No attempts yet
Time limit
40s
Memory limit
1024 MB
Judgeable
Yeetzhee
Hard8
Dynamic programming, Probability
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Kickstart Alarm
Hard8
Math, Combinatorics+2
No attempts yet
Time limit
90s
Memory limit
1024 MB
Judgeable
Paragliding
Hard8
Dynamic programming, Geometry
No attempts yet
Time limit
40s
Memory limit
1024 MB
Judgeable
Funniest Word Search
Hard8
String matching, Trie+2
No attempts yet
Time limit
240s
Memory limit
1024 MB
Judgeable
Specializing Villages
Hard8
Graph, Minimum spanning tree+2
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Combining Classes
Hard8
Binary search, Prefix sum+2
No attempts yet
Time limit
180s
Memory limit
1024 MB
Judgeable
Let Me Count The Ways
Hard8
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
40s
Memory limit
1024 MB
Judgeable
Two Cubes
Hard8
Binary search, Geometry+1
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Tricky Trios
Hard8
Probability, Greedy+1
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Seating Chart
Hard8
Combinatorics, Math+2
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Algorithm Class - Bubble Sort 6
Hard8
Sorting, Simulation+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Keycards
Hard8
Combinatorics, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Report
Hard8
Graph, DFS+2
No attempts yet
Time limit
0.5s
Memory limit
1024 MB
Judgeable
Sengoku
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
0.75s
Memory limit
1024 MB
Judgeable
Territory
Hard8
Geometry, Graph+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Nightman
Hard8
Geometry, Graph+2
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Oldest Ruins 2
Hard8
Dynamic programming, Geometry+2
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Coloring
Hard8
Combinatorics, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Rotation
Hard8
Greedy, Array+2
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Skewering
Hard8
Geometry, Probability+1
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
1D Anipang
Hard8
Dynamic programming, Segment tree+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Delivery
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Mini Bucket List
Hard8
Combinatorics, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Rain
Hard8
Greedy, Array+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Divide and Own
Hard8
Number theory, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Most Equal
Hard8
Dynamic programming, String+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Persistence
Hard8
Brute force, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Matching Colors
Hard8
Combinatorics, Math
No attempts yet
Time limit
0.4s
Memory limit
1024 MB
Judgeable
Common Factors
Hard8
Number theory, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Taxis 2
Hard8
Graph, BFS+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
K-th Shortest Path
Hard8
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Caffeine Addiction
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Prison Break
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Šarenlist
Hard8
Combinatorics, Tree+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Self Study
Hard8
Binary search, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Multiple Choice Test
Hard8
Geometry, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Drought
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sequence Reconstruction
Hard8
Graph, Union-find+2
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
blobblush
Hard8
Bit manipulation, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
blobfearful
Hard8
Number theory, Math+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
blobcry
Hard8
Graph, Math+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
blobpopcorn
Hard8
Segment tree, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Computing a Well-Known Sum
Hard8
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Meet In The Middle
Hard8
Tree, Graph+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Number of Words
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Perimeter Trail
Hard8
Geometry, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Queries on This Wonderful Sequence!
Hard8
Math, Segment tree+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Palindrome Game
Hard8
Game theory, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Gambling Game
Hard8
Combinatorics, Probability+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Good Triplets
Hard8
Combinatorics, Two pointers+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Subprime
Hard8
String matching, Math+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Tree Number Generator
Hard8
Tree, DFS+2
No attempts yet
Time limit
13s
Memory limit
1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Balanced Binary StringCount the ways to replace each '?' in a circular binary string with 0 or 1 so that every two circular substrings of the same length contain numbers of 1s differing by at most one, modulo 1e9+7.	Hard8	StringCombinatorics+2	No attempts yet	3s	512 MB	Judgeable
Knocking DownPick one point of a rectangle to pin, rotate it around that point, and find the fewest flags the sweep must knock down.	Hard8	GeometrySorting+1	No attempts yet	1s	64 MB	Judgeable
CoinsPlace N coins on an N by N board so each row and column holds one coin, moving coins one step at a time with no collisions, and minimize total moves.	Hard8	MathGreedy+2	No attempts yet	1s	128 MB	Judgeable
CakesThree eaters with different per-cake speeds share n cakes, each cake splittable into any proportions; find the minimum makespan.	Hard8	Binary searchGreedy+2	No attempts yet	3s	512 MB	Judgeable
Partial SumsRepeatedly apply the 2D prefix-sum map over GF(2) to a binary matrix and find the smallest positive number of applications that returns the original matrix.	Hard8	MathNumber theory+2	No attempts yet	1s	256 MB	Judgeable
Format a TableGiven a 3x3 table of cell text lengths and a total width w, split w into three column widths that minimize the sum of the three row heights.	Hard8	Brute forceMath+1	No attempts yet	5s	64 MB	Judgeable
Game with DominoesGiven n domino positions, choose a height h' in [hmin,hmax] that makes the second player win a game where each move topples a contiguous chain; output the smallest such h' or -1.	Hard8	Game theorySorting+2	No attempts yet	1s	64 MB	Judgeable
Everyone Loves Playing GamesTwo players alternately XOR one chosen value from each of their pairs into a running total; the first maximizes the final result and the second minimizes it, both playing optimally.	Hard8	Game theoryBit manipulation+2	No attempts yet	1s	256 MB	Judgeable
Yet Another Geometry ProblemFor each query point, find the largest axis-parallel integer square inside the M by M plane that strictly contains the point and no given point strictly.	Hard8	GeometrySorting+1	No attempts yet	4s	256 MB	Judgeable
A Math ProblemCount the fan-to-team assignments for n fans and m teams where the fan sets are closed under pairwise intersection and union, modulo 10^9+7.	Hard8	MathCombinatorics	No attempts yet	1s	256 MB	Judgeable
Security SystemFind the minimum number of non-touching horizontal or vertical tracks that let sensors watch every point of an x-monotone rectilinear polygon.	Hard8	GeometryGreedy+1	No attempts yet	0.8s	1024 MB	Judgeable
Distance in CrossesSquares are tiled by crosses whose centers form a lattice; moving to a different cross costs one coin, and we must find the minimum coins between two given squares.	Hard8	MathGeometry+2	No attempts yet	2s	512 MB	Judgeable
Galactic GovernmentsGiven up to 18 axis-aligned boxes in k up to 10 dimensions, find a half-integer lattice point not covered by any box, choosing the lexicographically smallest.	Hard8	BacktrackingBrute force+2	No attempts yet	2s	512 MB	Judgeable
MultiplicationGiven an even n, output n distinct numbers so that after multiplying by a secret odd x mod 2^31, the judge returns half of the products, and you must recover x.	Hard8	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Structure AlignmentParse a C struct declaration and, over all field orders, report the minimum, maximum, and average aligned memory size.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	2s	256 MB	Judgeable
Level checkGiven a fixed passable-cell map, decide for each layout whether the player can always reach a weapon before any monster, considering adversarial monster movement.	Hard8	GraphBFS+2	No attempts yet	4s	256 MB	Judgeable
Intersection GraphFor two axis-aligned boxes, list every nonempty boundary intersection as a point, curve, or surface and output its endpoints and incidences.	Hard8	GeometryImplementation+1	No attempts yet	1s	256 MB	Judgeable
Tower DefensePick a city in a tree so every tower covers it, where raising a tower's radius by x costs ceil(x/k), minimizing the total cost.	Hard8	TreeDivide and conquer+1	No attempts yet	5s	1024 MB	Judgeable
String ProductGiven a string s, find strings a and b with a times b equal to s (letters add mod 26), minimizing a+b lexicographically, then minimizing \|a\|.	Hard8	StringMath+2	No attempts yet	4s	256 MB	Judgeable
FenceEach segment is toggled independently with a given probability; find the expected total length of green points on the line.	Hard8	ProbabilityPrefix sum+2	No attempts yet	1s	256 MB	Judgeable
Algorithm Was AppliedGiven a connected graph, add edge b-c for each triple a<b<c where a-b and a-c are edges but b-c is not, then count n-color proper colorings of the final graph.	Hard8	GraphCombinatorics+1	No attempts yet	2s	512 MB	Judgeable
Equal Adjacent ElementsCount orders to remove elements of an array with no equal neighbors so that this stays true after every removal, modulo 998244353.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	2s	512 MB	Judgeable
Formally, You Choose Three IntegersDecide whether array a can be turned into array b by repeatedly cyclically shifting an even-length contiguous block by an even number of positions.	Hard8	MathArray+2	No attempts yet	2s	512 MB	Judgeable
HypercubeGiven a tree with n edges, place the maximum number of edge-disjoint copies in the n-dimensional hypercube and output every placement.	Hard8	Bit manipulationTree+2	No attempts yet	1s	512 MB	Judgeable
Edges CountingFor all labeled graphs on n vertices where each component has at most one cycle, sum the number of edges lying on a cycle, modulo p.	Hard8	CombinatoricsMath+2	No attempts yet	2s	256 MB	Judgeable
EquanimousFor each query (l, r), the task sums the integers m in [l, r] grouped by f(m), the minimal absolute signed-digit sum, for values 0 to 9, modulo 1e9+7.	Hard8	Dynamic programmingMath	No attempts yet	2s	256 MB	Judgeable
Three DimensionsSum the strange distance d(a,b) over all integer point pairs a and b inside two origin-anchored boxes, output modulo 2^30.	Hard8	Dynamic programmingBit manipulation+1	No attempts yet	1s	256 MB	Judgeable
Cyclic Shift and Minimal InversionsMaintain a permutation under subarray cyclic-shift updates, and after each update report the smallest shift k whose cyclic rotation has the fewest inversions.	Hard8	ArrayDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Filipp RukhovichSum the palindromicity of every subsequence of a string, counting each occurrence of a subsequence, modulo 998244353.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	6s	512 MB	Judgeable
Time is MoneyFind the shortest time from cabstand 1 to cabstand n when the k-th taxi pickup costs 2^(k-1) minutes of waiting, modulo 1e9+7.	Hard8	Shortest pathGraph+1	No attempts yet	2s	1024 MB	Judgeable
Two DotsGiven colored points on an L by L square, decide whether every same-colored pair can be joined by non-crossing curves inside the square.	Hard8	GeometrySorting+2	No attempts yet	1s	1024 MB	Judgeable
Vertex Merge GameOn a weighted connected graph, two players alternately color vertices and pick crossing edges; merging continues until one vertex remains. Decide the winner under optimal play.	Hard8	GraphGreedy+2	No attempts yet	3s	1024 MB	Judgeable
Rock Paper Scissors StrategyGiven N players and M games with participant lists and winners, count the strategy assignments (fixed hand, or cyclic RPS pattern) consistent with all results, modulo 1e9+7.	Hard8	ImplementationBrute force+1	No attempts yet	1s	1024 MB	Judgeable
Polygon AreaChoose at most K of N given points to form a simple polygon with maximum area, and print the area to one decimal place.	Hard8	GeometryDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
Dyson CircleGiven n unit-square stars on a grid, find the fewest unit squares forming a corner-connected ring that encloses all stars without edge leaks.	Hard8	GraphShortest path+1	No attempts yet	4s	1024 MB	Judgeable
Flatland OlympicsGiven a track segment and n seat locations, count the ordered pairs of visitors where one seat blocks the other's view of the track.	Hard8	GeometrySorting+1	No attempts yet	4s	1024 MB	Judgeable
Burizon FortA number m is practical when every integer from 1 to m-1 is a sum of distinct divisors of m; decide this for up to 100 values of m up to 10^12.	Hard8	Number theoryMath+2	No attempts yet	1.4s	1024 MB	Judgeable
Screamers in the StormCount sequences of length N with entries in 1..K where every adjacent pair is coprime, modulo 1e9+7, with N up to 1e18.	Hard8	Dynamic programmingMath+2	No attempts yet	2s	1024 MB	Judgeable
Valid Parenthesis StringA bracket string supports point flips and range queries that count how many ways the characters in [l, r] can be chosen so the whole string becomes a balanced parenthesis sequence.	Hard8	Segment treeCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Sequence (Hard)Sum the products A[B1]...A[BM] over all increasing index tuples B of length M whose chosen values are pairwise distinct, modulo 1e9+7.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	1s	512 MB	Judgeable
Jegi KickingChoose the smallest positive integer K so that applying the teacher's add/subtract rules to all scores makes the total at least S, or report -1 if no K works.	Hard8	Binary searchPrefix sum+2	No attempts yet	1s	512 MB	Judgeable
F1ow3rC0nMaintain an array of flower types under point updates and range queries. For each query, find the minimum number of glue bottles needed to attach petals to trees A through B in order, where each bottle covers one color but can be bought and discarded at will.	Hard8	Segment treeArray+2	No attempts yet	1s	512 MB	Judgeable
Bazza and ShazzaMaintain a huge implicit grid where cells start at 0; support point assignments and range GCD queries over rectangles, with coordinates up to 1e9 and values up to 1e18.	Hard8	Segment treeDynamic programming+2	No attempts yet	13s	230 MB	Judgeable
Bookshelf SortingGiven a permutation, repeatedly answer the minimum number of take-and-insert-at-ends moves to sort it, after each of q swaps of two positions.	Hard8	ArrayDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Garbage RobotGiven a room with one sofa, a robot's start cell and direction, count the cells where the robot leaves garbage before it shuts down, for each of q queries.	Hard8	SimulationMath+1	No attempts yet	2s	512 MB	Judgeable
HILOSum, over all permutations Elsie could guess with, the number of times the response string contains the substring HILO.	Hard8	CombinatoricsMath+2	No attempts yet	2s	1024 MB	Judgeable
Composite Function and Queries 2Maintain a function f on {1..N} under updates to f(1) and queries asking for the m-fold iterate f^m(x).	Hard8	GraphBinary search+2	No attempts yet	2s	512 MB	Judgeable
Painters' DuelTwo painters alternate moving through a triangular grid of rooms, avoiding blocked rooms, and the task asks for the best score Alma can guarantee under optimal play.	Hard8	Game theoryGraph+1	No attempts yet	40s	1024 MB	Judgeable
YeetzheeFor N dice with M faces, find the minimum expected number of rolls needed to finish with group sizes A, when each die can be rerolled before moving on.	Hard8	Dynamic programmingProbability	No attempts yet	20s	1024 MB	Judgeable
Kickstart AlarmGiven a generated array and K, sum over i=1..K of the total i-th exponential-power of every contiguous subarray, modulo 1e9+7.	Hard8	MathCombinatorics+2	No attempts yet	90s	1024 MB	Judgeable
ParaglidingGiven towers on the x-axis and balloons in the plane, find the most balloons Edge can collect by gliding at 45 degrees between towers.	Hard8	Dynamic programmingGeometry	No attempts yet	40s	1024 MB	Judgeable
Funniest Word SearchFind the subgrid of a letter grid that maximizes matched word length divided by width plus height, and count the subgrids that reach that maximum.	Hard8	String matchingTrie+2	No attempts yet	240s	1024 MB	Judgeable
Specializing VillagesAssign each village one of two foods so the average shortest distance to a village of the other food is minimized, and count the optimal assignments.	Hard8	GraphMinimum spanning tree+2	No attempts yet	20s	1024 MB	Judgeable
Combining ClassesGiven N score ranges and Q queries generated by linear recurrences, find the K-th largest score in the merged multiset and output the weighted sum of answers.	Hard8	Binary searchPrefix sum+2	No attempts yet	180s	1024 MB	Judgeable
Let Me Count The WaysCount permutations of 2N distinct people in a row so that none of M specified pairs sit adjacent, modulo 1e9+7.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	40s	1024 MB	Judgeable
Two CubesFind the smallest integer edge length of two axis-parallel cubes so that every sphere lies completely inside at least one of the cubes.	Hard8	Binary searchGeometry+1	No attempts yet	20s	1024 MB	Judgeable
Tricky TriosGiven a face-down deck of 3N cards with three copies each of 1 to N, find the minimum expected number of rounds to remove every trio by flipping cards.	Hard8	ProbabilityGreedy+1	No attempts yet	20s	1024 MB	Judgeable
Seating ChartCount the distinct seating arrangements of N labeled people at K round tables with sizes differing by at most one, where only adjacency matters and table order is irrelevant.	Hard8	CombinatoricsMath+2	No attempts yet	20s	1024 MB	Judgeable
Algorithm Class - Bubble Sort 6Given arrays A and B, decide whether bubble sort on A produces exactly B at some point within the first K adjacent swaps.	Hard8	SortingSimulation+2	No attempts yet	3s	512 MB	Judgeable
KeycardsCount the subsets of the 2N possible keys (a nonempty collection) such that exactly K of the N positions are punched in every chosen key, modulo 1e9+7.	Hard8	CombinatoricsMath+1	No attempts yet	1s	1024 MB	Judgeable
ReportEach person reports job i to a fixed target, and the report keeps forwarding until a repeat. For each person, output how many distinct jobs' reports reached them before they start their own job.	Hard8	GraphDFS+2	No attempts yet	0.5s	1024 MB	Judgeable
SengokuCount the cells of an L by L grid covered by at least one of N diagonal watchmen, where a watchman at (x, y) covers every cell with \|x-i\| = \|y-j\|.	Hard8	GeometrySorting+1	No attempts yet	0.75s	1024 MB	Judgeable
TerritoryA recorded walk on a grid traces a closed curve; find the largest region enclosed by parts of the path, or 0 if none exists.	Hard8	GeometryGraph+2	No attempts yet	1s	1024 MB	Judgeable
NightmanGiven up to 10 guards, 50 axis-aligned rectangular obstacles, and 10 query points in a rectangle, find the shortest obstacle-avoiding path from each query to its nearest guard and sum the doubled distances.	Hard8	GeometryGraph+2	No attempts yet	5s	1024 MB	Judgeable
Oldest Ruins 2Given N points with no three collinear, find the largest subset that forms a convex polygon and report its vertex count.	Hard8	Dynamic programmingGeometry+2	No attempts yet	1.5s	1024 MB	Judgeable
ColoringCount sequences of N cells where each cell takes one of two distinct color types from chosen bags i and j, summing over all pairs with i different from j.	Hard8	CombinatoricsMath+2	No attempts yet	1s	512 MB	Judgeable
RotationGiven a permutation, repeatedly rotate any contiguous block left or right at a cost equal to the block length; find the minimum total cost to sort it into increasing order.	Hard8	GreedyArray+2	No attempts yet	8s	1024 MB	Judgeable
SkeweringGiven N segments, pick a and b uniformly from (0,1] and find the probability that line ax+by=1 touches exactly i segments, reported as a modular value.	Hard8	GeometryProbability+1	No attempts yet	8s	1024 MB	Judgeable
1D AnipangEach round asks the minimum cost to make an array have no two adjacent equal-sign values, using flips costing R and increments costing C, with point updates across T+1 rounds.	Hard8	Dynamic programmingSegment tree+2	No attempts yet	2s	1024 MB	Judgeable
DeliveryGiven N deliveries, each at a specific time and house on a line of 10^9 houses, find the minimum number of trucks that can start anywhere and serve all requests, moving at one house per unit time.	Hard8	GreedySorting+2	No attempts yet	2s	1024 MB	Judgeable
Mini Bucket ListCount the ways to place N tasks with given lengths into K unit time slots so that no two overlap, modulo 1e9+7.	Hard8	CombinatoricsMath+2	No attempts yet	1s	1024 MB	Judgeable
RainGiven barrier heights in a box and a set of barriers whose heights may be raised by bounded amounts, find the minimum number of barriers to raise and the maximum water the box can then hold.	Hard8	GreedyArray+2	No attempts yet	2s	1024 MB	Judgeable
Divide and OwnFor each pair (a, b), you may move any prime factor from one number to the other; find the maximum achievable gcd.	Hard8	Number theoryMath+1	No attempts yet	1s	1024 MB	Judgeable
Most EqualGiven N strings over the first M letters, find a K-letter string P (distinct letters, order preserved) that appears as a subsequence in the most strings; report that count, the lexicographically smallest such P, and how many distinct P achieve it.	Hard8	Dynamic programmingString+2	No attempts yet	1s	1024 MB	Judgeable
PersistenceGiven a persistence P, find the smallest non-negative integer whose repeated digit-product process reaches a single digit in exactly P steps.	Hard8	Brute forceGreedy+2	No attempts yet	1s	1024 MB	Judgeable
Matching ColorsCount the red and blue fillings of an N by M grid where every cell has a same-colored cell in its row or column, modulo 1000000007.	Hard8	CombinatoricsMath	No attempts yet	0.4s	1024 MB	Judgeable
Common FactorsGiven n up to 1e18, find the maximum over k in [2,n] of the fraction of integers in [1,k] that share a factor greater than 1 with k, and print it in lowest terms.	Hard8	Number theoryMath+1	No attempts yet	1s	1024 MB	Judgeable
Taxis 2For each query town, find the minimum starting money needed to travel from town 1 along red (cost 1) and blue (halve, floor) taxi edges while staying at least 1 yen, or report Large if it exceeds L.	Hard8	GraphBFS+2	No attempts yet	4s	1024 MB	Judgeable
K-th Shortest PathGiven two L-digit numbers, list the K-th lexicographically shortest path between them in a graph where edges connect digits differing by 1 in one place.	Hard8	GraphBFS+2	No attempts yet	1s	512 MB	Judgeable
Caffeine AddictionChoose the order to drink N energy drinks, each adding max(0, E_i - accumulated caffeine) awake seconds and C_i caffeine, maximizing total awake time.	Hard8	GreedySorting+2	No attempts yet	1s	1024 MB	Judgeable
Prison BreakGiven a convex polygon and points inside or outside it, count the polygon edges that no outside guard can see, where a guard sees an edge if it subtends a view that reaches the edge.	Hard8	GeometrySorting+2	No attempts yet	2s	512 MB	Judgeable
ŠarenlistCount the ways to color the edges of a tree with k colors so that each of m given paths contains at least two different colors, modulo 1e9+7.	Hard8	CombinatoricsTree+2	No attempts yet	1s	512 MB	Judgeable
Self StudyGiven N courses over M weeks, each class Bitaro either attends (gaining A_i in course i) or self-studies one course (gaining B_i); maximize the minimum final comprehension across all courses.	Hard8	Binary searchGreedy+2	No attempts yet	1s	512 MB	Judgeable
Multiple Choice TestPick one vector from each of N groups so the squared distance of the total sum from the origin is maximized.	Hard8	GeometryGreedy+2	No attempts yet	1s	1024 MB	Judgeable
DroughtCount N-tuples of hunger levels within given upper bounds for which adjacent-pair feedings can make all cows equal, modulo 1e9+7.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	1s	1024 MB	Judgeable
Sequence ReconstructionGiven M equations of the form a_i + a_j = k, reconstruct the integer sequence a_1..a_N or report ERROR when more than one solution exists.	Hard8	GraphUnion-find+2	No attempts yet	3s	256 MB	Judgeable
blobblushChoose a subset of {1,...,N} whose XOR is maximum, then among those use the fewest cards, then the lexicographically smallest set, and output it sorted.	Hard8	Bit manipulationGreedy+2	No attempts yet	1s	1024 MB	Judgeable
blobfearfulFor each starting blob count A, find the smallest day i such that the running product A23...i is a multiple of K.	Hard8	Number theoryMath+2	No attempts yet	2s	1024 MB	Judgeable
blobcryGiven a connected simple graph, repeatedly delete any two edges incident to one vertex; list all edges that can be the last remaining edge.	Hard8	GraphMath+2	No attempts yet	3s	1024 MB	Judgeable
blobpopcornGiven distinct heights in a line, count pairs whose interior blobs are all shorter than both endpoints, under point updates to heights.	Hard8	Segment treeCombinatorics+2	No attempts yet	2s	1024 MB	Judgeable
Computing a Well-Known SumSum f(i)*g(i) for i from 1 to N, where f(i)=N div i and g(i)=i mod M, with N and M up to 1e9, modulo 1e9+7.	Hard8	MathNumber theory+2	No attempts yet	1s	1024 MB	Judgeable
Meet In The MiddleGiven a weighted tree and K queries each naming two villages, find the village where the two distances are equal, breaking ties by the smallest total distance, or -1.	Hard8	TreeGraph+2	No attempts yet	1s	1024 MB	Judgeable
Number of WordsGiven a run-length compressed string, count the number of distinct subsequences of the fully expanded string, modulo 998244353.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	1s	1024 MB	Judgeable
Perimeter TrailGiven up to 500 distinct integer points, find the largest number of points that can lie on the perimeter of an axis-parallel rectangle.	Hard8	GeometryBrute force+2	No attempts yet	2s	512 MB	Judgeable
Queries on This Wonderful Sequence!After each update that pins a Fibonacci-indexed segment to a new value, report the current value at segment N, all modulo 1e9+7.	Hard8	MathSegment tree+2	No attempts yet	4s	1024 MB	Judgeable
Palindrome GameWith a pile of N stones, players alternately remove a palindromic number of stones; determine whether the first player wins.	Hard8	Game theoryDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
Gambling GameGiven m, n, and p, compute the probability that a card's n disjoint pairs are all covered exactly on the p-th of m balls drawn without replacement, as a reduced fraction.	Hard8	CombinatoricsProbability+2	No attempts yet	1s	1024 MB	Judgeable
Good TripletsCount index triplets whose three points on a circle of integer circumference C contain the origin strictly inside their triangle.	Hard8	CombinatoricsTwo pointers+2	No attempts yet	1s	1024 MB	Judgeable
SubprimeCount primes among the lth through hth smallest primes whose decimal representation contains the given digit string p, counting each prime once.	Hard8	String matchingMath+2	No attempts yet	2s	1024 MB	Judgeable
Tree Number GeneratorGiven a tree whose nodes hold digits, answer queries that read the digit string along the path from a to b and return its value modulo m.	Hard8	TreeDFS+2	No attempts yet	13s	1024 MB	Judgeable