Math and counting

Number theory, combinatorics, and geometry

Under construction

Still being built. Things may change

Total results13,164 problems

Pipe Marbles
Hard8
Dynamic programming, String+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Course Design
Hard8
Tree, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Counting Spanning Trees
Hard8
Matrix, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Union of Balls
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Binary Transformation
Hard8
Greedy, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Circumcenter of a Tree
Hard8
Tree, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Time Dragging
Hard8
Greedy, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
G++ Language
Hard8
Bit manipulation, Implementation+1
No attempts yet
Time limit
0.1s
Memory limit
256 MB
Judgeable
Complaints Pile Up
Hard8
Binary search, Geometry+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
2xN Tiling with Queries
Hard8
Dynamic programming, Segment tree+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Function Composition and Queries
Hard8
Binary search, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Kopo-bread Tournament
Hard8
Probability, Combinatorics+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Making a Flyswatter
Hard8
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Transparent Crocodiles
Hard8
Dynamic programming, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
The Little Match Girl
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Deadly! 60-Note Combo
Hard8
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Good Set
Hard8
Bit manipulation, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Bohemian Rhaksody
Hard8
Dynamic programming, Segment tree+1
No attempts yet
Time limit
6.5s
Memory limit
1024 MB
Judgeable
Sequence and Queries 28
Hard8
Segment tree, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Border
Hard8
Graph, Brute force+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Hilbert's Hotel
Hard8
Math, Implementation+2
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Maximizer
Hard8
Greedy, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Paris by Night
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
15s
Memory limit
512 MB
Judgeable
Travel Guide
Hard8
Shortest path, Graph+2
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Garden Variety Vampire
Hard8
Geometry, Bit manipulation+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Balance Scale
Hard8
Math, Hash map+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Running Routes
Hard8
Dynamic programming, Intervals+2
No attempts yet
Time limit
12s
Memory limit
1024 MB
Judgeable
Stop Counting!
Hard8
Math, Prefix sum+2
No attempts yet
Time limit
7s
Memory limit
1024 MB
Judgeable
Frog Jump
Hard8
Geometry, Union-find+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Brackets
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
XORanges
Hard8
Bit manipulation, Segment tree+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Strange Machine
Hard8
Math, Number theory+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Amusement Park
Hard8
Bit manipulation, Dynamic programming+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Sum of Squares 2 (More Huge)
Hard8
Math, Number theory+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Exam
Hard8
Sorting, Prefix sum+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Minerals
Hard8
Divide and conquer, Implementation+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Fences
Hard8
Geometry, Shortest path+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Tents
Hard8
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Library
Hard8
Intervals, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Broken Device
Hard8
Bit manipulation, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Dragon 2
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
IOIOI Cards
Hard8
Shortest path, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Constellation 2
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
9s
Memory limit
512 MB
Judgeable
Collecting Images is Fun
Hard8
Divide and conquer, Implementation+2
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Mascots
Hard8
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Equation
Hard8
Math, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Conveyor Belts
Hard8
Math, Number theory+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Estate Agent
Hard8
Graph, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Mosaic Mansion
Hard8
Dynamic programming, Hash map+2
No attempts yet
Time limit
12s
Memory limit
512 MB
Judgeable
Lion and Rabbit
Hard8
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Fibonacci Music
Hard8
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Cheese, If You Please
Hard8
Math, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Circle Garden
Hard8
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Integers in Rational Bases
Hard8
Number theory, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Hogwarts
Hard8
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Molecules
Hard8
Graph, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Watch Later
Hard8
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Loo Rolls
Hard8
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Type Charts
Hard8
Math, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Dice and Ladders
Hard8
Probability, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Counting Permutations with a Given Greedily Increasing Subsequence
Hard8
Combinatorics, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Logland
Hard8
Bit manipulation, Greedy+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Ranch CCTV
Hard8
Prefix sum, Matrix+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Pizza Grows as You Slice It
Hard8
Math, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Max or Min
Hard8
Implementation, Greedy+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Game on a Tree
Hard8
Tree, Game theory+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Washer
Hard8
Geometry, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Drive Safely
Hard8
Dynamic programming, Geometry+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Fixed Point Permutations
Hard8
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Interstellar Travel
Hard8
Geometry, Math+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Glow, Pixel, Glow!
Hard8
Sorting, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Harder Staircase Numbers
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Algorithm Teaching
Hard8
Combinatorics, Bit manipulation+1
No attempts yet
Time limit
1.5s
Memory limit
512 MB
Judgeable
Building the Perfect House
Hard8
Geometry, Binary search+2
No attempts yet
Time limit
1.5s
Memory limit
512 MB
Judgeable
Cut Inequality Down
Hard8
Segment tree, Implementation+2
No attempts yet
Time limit
0.7s
Memory limit
512 MB
Judgeable
Dazzling Stars
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
0.2s
Memory limit
512 MB
Judgeable
Hold or Continue?
Hard8
Dynamic programming, Probability+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Antennas
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Golf Time
Hard8
Simulation, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Disposable Switches
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Gnoll Hypothesis
Hard8
Probability, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Popcount
Hard8
Bit manipulation, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
ICPC
Hard8
Combinatorics, String matching+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Great Farmer Kim Sanghyuk
Hard8
Geometry, Math+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Miss Sloane
Hard8
Number theory, Greedy+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Optimal Selection
Hard8
Divide and conquer, Game theory+2
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Evaluation
Hard8
Implementation, Recursion+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Zeldain Garden
Hard8
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Light Emitting Hindenburg
Hard8
Bit manipulation, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Candles and Shadows
Hard8
Geometry, Binary search+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Fraction Calculation
Hard8
Math, Sorting+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Twin Trees Bros.
Hard8
Tree, Geometry+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Sink the Billiard Ball
Hard8
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Who Has Not Read the Message?
Hard8
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Find The Number
Hard8
Math, Binary search+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Meetings
Hard8
Sorting, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Dramatic Duel
Hard8
Game theory, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Coloring a Rectangle 2
Hard8
Dynamic programming, Matrix+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Cave Paintings
Hard8
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Loan Repayment
Hard8
Binary search, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Pipe MarblesGiven two binary strings as stacks, count the sum of squares of the number of interleavings producing each distinct output string, modulo 1024523.	Hard8	Dynamic programmingString+2	No attempts yet	1s	512 MB	Judgeable
Course DesignPartition the cities into disjoint paths so the maximum number of coach edges on any city's route to the capital is minimized, then count the optimal partitions modulo Q.	Hard8	TreeDynamic programming+1	No attempts yet	1s	256 MB	Judgeable
Counting Spanning TreesCount spanning trees of a path graph where every pair of nodes at distance at most k is joined, k <= 5, n <= 10^15, modulo 65521.	Hard8	MatrixDynamic programming+2	No attempts yet	1s	256 MB	Judgeable
Union of BallsAll ball centers lie on the x-axis, so the union is a solid of revolution; compute its volume as p/q times pi and output p times q inverse mod 1e9+7.	Hard8	GeometrySorting+2	No attempts yet	2s	1024 MB	Judgeable
Binary TransformationChoose a chain of N numbers from x0 to 0, each step clearing some 1 bits, so the set of adjacent differences has the smallest possible max minus min.	Hard8	GreedyBit manipulation+2	No attempts yet	1s	512 MB	Judgeable
Circumcenter of a TreeGiven a tree and many triples of vertices, for each triple report the unique vertex equidistant from all three (with equal distances as small as possible) or -1 if none exists.	Hard8	TreeGraph+2	No attempts yet	2s	512 MB	Judgeable
Time DraggingGiven an N by M board with marked cells, find the longest sequence of row and column picks such that no pick creates a marked intersection among chosen lines.	Hard8	GreedyGraph+2	No attempts yet	1s	512 MB	Judgeable
G++ LanguageWrite a G++ program that reads H and W, then leaves the sum of the cells in the rectangle from (a, b) to (c, d) in memory 0 and zeros elsewhere.	Hard8	Bit manipulationImplementation+1	No attempts yet	0.1s	256 MB	Judgeable
Complaints Pile UpFind the largest integer volume V so that each speaker's Manhattan-distance sound range, with radius V times its size, never overlaps another speaker's range.	Hard8	Binary searchGeometry+1	No attempts yet	5s	512 MB	Judgeable
2xN Tiling with QueriesMaintain the count of tilings of a 2xN grid by 1x2 and 2x1 tiles while cells get blocked and unblocked by queries.	Hard8	Dynamic programmingSegment tree+2	No attempts yet	2s	256 MB	Judgeable
Function Composition and QueriesGiven a function f on 1..m, answer queries n, x by returning the value of the n-fold composition f^n(x).	Hard8	Binary searchGraph+2	No attempts yet	1s	512 MB	Judgeable
Kopo-bread TournamentFor each rating range [A, B], find the expected number of values recorded in a random-order knockout tournament, as a value modulo 10^9+7.	Hard8	ProbabilityCombinatorics+1	No attempts yet	5s	1024 MB	Judgeable
Making a FlyswatterGiven a simple polygon, find the expected squared distance between two points chosen independently and uniformly inside it.	Hard8	GeometryMath+2	No attempts yet	1s	1024 MB	Judgeable
Transparent CrocodilesGiven claw mark counts at each swamp position, find the minimum total front-to-back paw distance of crocodiles that leave exactly those marks, or -1 if impossible.	Hard8	Dynamic programmingMath+1	No attempts yet	1s	1024 MB	Judgeable
The Little Match GirlChoose for each of N integers to skip it, multiply by its negative for 1 matchstick, or multiply by its positive value for 2 matchsticks, spending at most K, to maximize the product modulo 1e9+7.	Hard8	GreedySorting+2	No attempts yet	1s	1024 MB	Judgeable
Deadly! 60-Note ComboFor each query (a, b, c), count how many binary strings x with a <= x <= b score strictly higher than c in a 60-note combo game, where a GOOD after a combo of X gives 2X-1 points.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	2s	1024 MB	Judgeable
Good SetCount the nonempty subsets of {0, ..., 2^k - 1} that are closed under bitwise AND and OR and contain all given n integers, with k up to 7.	Hard8	Bit manipulationDynamic programming+1	No attempts yet	1s	1024 MB	Judgeable
Bohemian RhaksodyEach bulb lights one of four half-planes (x at most X, x at least X, y at most Y, or y at least Y), and the task is to find the largest area the bulbs light together.	Hard8	Dynamic programmingSegment tree+1	No attempts yet	6.5s	1024 MB	Judgeable
Sequence and Queries 28Maintain an array under range add, range floor-sqrt, and range sum queries, and report each range sum.	Hard8	Segment treeMath+2	No attempts yet	1s	512 MB	Judgeable
BorderGiven an N by N grid of species (N at most 4), find a non-self-crossing border path from the top-left to the bottom-right corner so that different species end up in separate regions, or report that none exists.	Hard8	GraphBrute force+2	No attempts yet	1s	256 MB	Judgeable
Hilbert's HotelSimulate Hilbert's Hotel as guests arrive in finite or infinite groups, and answer which group occupies a room or which room holds a given index of a group.	Hard8	MathImplementation+2	No attempts yet	1.5s	1024 MB	Judgeable
MaximizerGiven two permutations A and B of 1..N, find the minimum number of adjacent swaps in A needed to reach a permutation maximizing the sum of \|a_i - b_i\|.	Hard8	GreedyCombinatorics+2	No attempts yet	2s	1024 MB	Judgeable
Paris by NightGiven N graded points in general position, pick two boundary monuments and split the rest by the line through them to minimize the absolute difference of the two side sums.	Hard8	GeometrySorting+2	No attempts yet	15s	512 MB	Judgeable
Travel GuideGiven a weighted undirected graph with three special nodes, count the vertices that are not dominated in all three distances by another vertex.	Hard8	Shortest pathGraph+2	No attempts yet	6s	512 MB	Judgeable
Garden Variety VampireGiven three points and n circle radii, decide whether the circles can be placed so their union connects all three points.	Hard8	GeometryBit manipulation+1	No attempts yet	1s	512 MB	Judgeable
Balance ScaleGiven a set of existing weights and target amounts, find the lightest single new weight that makes every amount expressible as a signed subset sum of the weights, or report 0 or -1.	Hard8	MathHash map+2	No attempts yet	2s	512 MB	Judgeable
Running RoutesGiven chords of a convex n-gon, find the largest set of chords no two of which share any common point, including endpoints.	Hard8	Dynamic programmingIntervals+2	No attempts yet	12s	1024 MB	Judgeable
Stop Counting!Given a deck of integers, choose one contiguous block to skip so the average of the remaining cards is maximized.	Hard8	MathPrefix sum+2	No attempts yet	7s	1024 MB	Judgeable
Frog JumpGiven N disjoint horizontal line segments, two logs are connected if a vertical jump between them crosses no other log; answer queries on whether logs are reachable.	Hard8	GeometryUnion-find+1	No attempts yet	1s	512 MB	Judgeable
BracketsFor each N, find the valid bracket string with bracket value N whose digit-encoded decimal value is smallest, and print it.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	512 MB	Judgeable
XORangesMaintain an array under point updates and answer queries for the XOR of every contiguous subarray inside [l, u].	Hard8	Bit manipulationSegment tree+2	No attempts yet	1s	512 MB	Judgeable
Strange MachineCount the distinct pairs (x, y) produced by the map t -> (((t + floor(t/B)) mod A), t mod B) over n disjoint time intervals.	Hard8	MathNumber theory+2	No attempts yet	4s	512 MB	Judgeable
Amusement ParkGiven up to 18 attractions and directed slides, sum the number of reversed slides over all direction choices that leave no cycle, modulo 998244353.	Hard8	Bit manipulationDynamic programming+2	No attempts yet	3s	512 MB	Judgeable
Sum of Squares 2 (More Huge)Given n up to 10^18, find the minimum number of perfect squares summing to n and output the actual square roots used.	Hard8	MathNumber theory+2	No attempts yet	0.5s	512 MB	Judgeable
ExamFor each of Q threshold triples, count students with S>=X, T>=Y, and S+T>=Z, where N and Q reach 100000.	Hard8	SortingPrefix sum+2	No attempts yet	3s	1024 MB	Judgeable
MineralsGiven 2N slices forming N unknown pairs, determine all pairs using at most 1,000,000 device operations that report the number of distinct mineral kinds currently inserted.	Hard8	Divide and conquerImplementation+2	No attempts yet	1s	256 MB	Judgeable
FencesGiven a square pasture and existing fence segments, find the minimum total length of new fences needed to fully enclose the pasture inside the lot.	Hard8	GeometryShortest path+1	No attempts yet	1s	256 MB	Judgeable
TentsCount nonempty subsets of tents on an H by W grid with directions obeying monotone entrance rules in every row and column, modulo 1e9+7.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
LibraryGiven a hidden permutation of N books, query the oracle with a set of book numbers and receive the minimum number of contiguous-block removals needed to extract exactly those books, then recover the order.	Hard8	IntervalsMath+2	No attempts yet	2s	512 MB	Judgeable
Broken DeviceBuild a 150-bit sequence for a 64-bit integer X so the receiver can recover X even when up to 40 unknown positions are forced to 0.	Hard8	Bit manipulationMath+1	No attempts yet	2s	512 MB	Judgeable
Dragon 2For each conflict, count the fireballs from tribe F's dragons toward tribe G's dragons whose half-lines cross the road between the two villages.	Hard8	GeometrySorting+1	No attempts yet	2s	512 MB	Judgeable
IOIOI CardsGiven a row of I/O cards and interval flip operations with per-length costs, decide whether all cards can be turned face up and find the minimum total flip time.	Hard8	Shortest pathGraph+2	No attempts yet	1s	512 MB	Judgeable
Constellation 2Count unordered pairs of non-overlapping triangles, each with one red, one blue, and one yellow star, among N colored points.	Hard8	GeometrySorting+1	No attempts yet	9s	512 MB	Judgeable
Collecting Images is FunStart with an all-white 2^N by 2^N grid; after each of Q row or column flips, report the size of the quadtree that represents the image.	Hard8	Divide and conquerImplementation+2	No attempts yet	5s	256 MB	Judgeable
MascotsCount the orders of placing the remaining mascots so that the number of steps where the occupied cells form a full rectangle is maximized, modulo 1e9+7.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	2s	256 MB	Judgeable
EquationCount integers n in [a, b] up to 10^18 with k times the sum of squares of n's decimal digits equal to n.	Hard8	MathBrute force+2	No attempts yet	2s	512 MB	Judgeable
Conveyor BeltsBuild a belt network of at most 200 fixed a:b splitters that divides one global input into c:d between the two outputs, given a, b, c, and d.	Hard8	MathNumber theory+1	No attempts yet	1s	512 MB	Judgeable
Estate AgentGiven directed offers between families with amounts, pick a subset of disjoint cycles so the total sum of offer amounts is maximized, then output 5% of it.	Hard8	GraphDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Mosaic MansionGiven n rows of m colored tiles, remove rows so that the kept rows contain the same number of tiles of each color; maximize the number of kept rows.	Hard8	Dynamic programmingHash map+2	No attempts yet	12s	512 MB	Judgeable
Lion and RabbitCount the ordered pairs of distinct vertices in a connected undirected graph for which the lion can never catch the rabbit under simultaneous blind moves.	Hard8	GraphBFS+2	No attempts yet	1s	256 MB	Judgeable
Fibonacci MusicBuild a digit string from Fibonacci numbers reduced mod M and answer queries for the N-th digit, with N up to 10^15.	Hard8	MathNumber theory+2	No attempts yet	1s	512 MB	Judgeable
Cheese, If You PleaseGiven limited pounds of n cheese types and m blends with fixed percentage recipes and per-pound profits, find the maximum achievable profit and round it to the nearest cent.	Hard8	MathGreedy+2	No attempts yet	2s	512 MB	Judgeable
Circle GardenGiven side lengths of a cyclic polygon, find the circumradius, or report no circle, an outside center, or a radius over 120 inches.	Hard8	GeometryMath+2	No attempts yet	1s	512 MB	Judgeable
Integers in Rational BasesGiven coprime p and q, write a positive integer n in the unique base p/q expansion whose digits are all at most p-1, printing digits 0-9, A-Z, a-z.	Hard8	Number theoryMath+2	No attempts yet	1s	512 MB	Judgeable
HogwartsGiven two edge-labelled 4-out graphs on n rooms, decide whether every instruction sequence that walks from room 1 to room n in the old graph also walks from 1 to n in the new graph.	Hard8	GraphBFS+2	No attempts yet	1s	512 MB	Judgeable
MoleculesGiven a connected graph with some vertex positions fixed, find positions for the rest so each unknown vertex sits at the average of its neighbors; any valid solution is accepted.	Hard8	GraphMath+2	No attempts yet	2s	512 MB	Judgeable
Watch LaterGiven a string of video types, find the minimum number of manual clicks needed to watch everything, where playback auto-advances to the next video only if it has the same type.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	6s	512 MB	Judgeable
Loo RollsFind the smallest number of loo rolls, each of length l, so that consuming n per visit never triggers a shortage.	Hard8	MathNumber theory+2	No attempts yet	1s	512 MB	Judgeable
Type ChartsGiven observed results of type-1 attacks on single or double-typed Nudgémon, the task is to output a first row of the type chart that matches every observation.	Hard8	MathBit manipulation+1	No attempts yet	2s	512 MB	Judgeable
Dice and LaddersFind the minimum number of die rolls so that the probability of finishing a snakes-and-ladders board within that many rolls is at least p.	Hard8	ProbabilityDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Counting Permutations with a Given Greedily Increasing SubsequenceCount the permutations of 1 to N whose greedily increasing subsequence equals a given sequence G, modulo 1e9+7.	Hard8	CombinatoricsMath+2	No attempts yet	1s	512 MB	Judgeable
LoglandGiven coin counts for powers of two up to 2^(k-1), find the least total value that must be left behind so the rest splits into two equal halves, modulo 1e9+7.	Hard8	Bit manipulationGreedy+1	No attempts yet	1s	512 MB	Judgeable
Ranch CCTVFor each query, sheep in a grid shift one cell per day in a fixed direction for K days; report the XOR of the daily maximum over the CCTV rectangle.	Hard8	Prefix sumMatrix+2	No attempts yet	2s	256 MB	Judgeable
Pizza Grows as You Slice ItFor each K, choose the number of cuts that maximizes the pieces kept after giving away 1+2+...+k pieces to Yunhee.	Hard8	MathCombinatorics+1	No attempts yet	1s	256 MB	Judgeable
Max or MinGiven numbers on a circle and min/max operations over a value and its two neighbors, find for each x the least minutes to make all values equal x, or -1.	Hard8	ImplementationGreedy+2	No attempts yet	1s	256 MB	Judgeable
Game on a TreeAlice places a chip on a white node of a rooted tree, then players alternately move it to an unvisited ancestor or descendant, blackening that node; the player who cannot move loses. Determine the winner.	Hard8	TreeGame theory+2	No attempts yet	1s	256 MB	Judgeable
WasherPartition up to 100 points in 3D into at most k groups (k <= 2) to minimize the sum of squared distances to each group's centroid.	Hard8	GeometryDivide and conquer+2	No attempts yet	1s	512 MB	Judgeable
Drive SafelyPlace k speed limit signs on a polyline road so that travel time is minimized, where each turn caps the speed limit by \|180 - alpha\| km/h.	Hard8	Dynamic programmingGeometry+2	No attempts yet	1s	512 MB	Judgeable
Fixed Point PermutationsFind the kth lexicographically smallest permutation of 1..n having exactly m fixed points, or print -1 if fewer than k exist.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Interstellar TravelGiven n angular intervals where each star contributes t - s*dist(a,b), find the launch angle b maximizing the sum of contributions.	Hard8	GeometryMath+2	No attempts yet	5s	512 MB	Judgeable
Glow, Pixel, Glow!Given horizontal and vertical pulses crossing a grid of wires, count the pixels where current passes through both intersecting wires at the same time.	Hard8	SortingImplementation+2	No attempts yet	2s	512 MB	Judgeable
Harder Staircase NumbersCount the length-N B-ary staircase numbers (adjacent digits differ by 1, no leading zero) that use every digit from 0 to B-1, modulo M.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	2s	1024 MB	Judgeable
Algorithm TeachingGiven teachers who each know up to 10 named algorithms, find the largest team of students whose training subsets are pairwise incomparable.	Hard8	CombinatoricsBit manipulation+1	No attempts yet	1.5s	512 MB	Judgeable
Building the Perfect HouseGiven N points, none at the origin, find the largest square centered at the origin that contains no point strictly inside it, then print its perimeter to four decimals.	Hard8	GeometryBinary search+2	No attempts yet	1.5s	512 MB	Judgeable
Cut Inequality DownFor many range queries [B,E] and starting wealth X, simulate monthly income with wealth clamped into [L,U] after each month and report the final wealth.	Hard8	Segment treeImplementation+2	No attempts yet	0.7s	512 MB	Judgeable
Dazzling StarsGiven N stars with coordinates and brightness, decide whether some rotation of the picture makes brighter stars print no later than dimmer ones, where printing goes top to bottom.	Hard8	GeometrySorting+2	No attempts yet	0.2s	512 MB	Judgeable
Hold or Continue?For each query state (Catelyn score, Hoster score, current turn total) decide hold or continue to maximize Catelyn's win probability when both play optimally in Pig to exactly 75.	Hard8	Dynamic programmingProbability+2	No attempts yet	2s	512 MB	Judgeable
AntennasGiven a convex polygon with antennas inside, count the antenna pairs whose connecting line crosses neither of two removed walls, for each removal scenario.	Hard8	GeometrySorting+1	No attempts yet	8s	512 MB	Judgeable
Golf TimeFor each start point, find when a diagonal ball bouncing off the course walls first hits the pond and where, or report that it never does.	Hard8	SimulationMath+1	No attempts yet	2s	512 MB	Judgeable
Disposable SwitchesFind the switches that never lie on an optimal path from switch 1 to switch n, whatever the cable speed and per-cable overhead turn out to be.	Hard8	GraphShortest path+1	No attempts yet	4s	512 MB	Judgeable
Gnoll HypothesisGiven n spawn probabilities and a random pool of k chosen types, compute each type's expected effective spawn chance after unchosen chances shift to the next chosen type cyclically.	Hard8	ProbabilityDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
PopcountGiven N and K, produce a MalnarScript program of at most K commands that computes the popcount of an N-bit input using one variable.	Hard8	Bit manipulationDivide and conquer+2	No attempts yet	1s	512 MB	Judgeable
ICPCConcatenate all lowercase words of length 1 through N in length-then-alphabetical order; count occurrences of the substring "icpc" modulo 1e9+7, with N up to 1e9.	Hard8	CombinatoricsString matching+2	No attempts yet	2s	512 MB	Judgeable
Great Farmer Kim SanghyukChoose a radius r to maximize the daily profit from crops inside the circle (each worth wi times its distance to the boundary) minus the management cost A*r^2.	Hard8	GeometryMath+2	No attempts yet	2s	1024 MB	Judgeable
Miss SloaneChoose senators to lobby, dividing each chosen a_i by a divisor at most k, so that the gcd of all final values is greater than 1, minimizing the total lobbying time.	Hard8	Number theoryGreedy+1	No attempts yet	5s	1024 MB	Judgeable
Optimal SelectionGiven n <= 8 numbers and some known pairwise order relations, find the worst-case minimum number of comparisons an optimal comparison-based algorithm needs to output the k-th smallest.	Hard8	Divide and conquerGame theory+2	No attempts yet	8s	1024 MB	Judgeable
EvaluationEvaluate an expression drawn as 2D ASCII art modulo 10^9+7, where the art encodes numbers, parentheses, fourth roots, operators, and fractions.	Hard8	ImplementationRecursion+1	No attempts yet	2s	512 MB	Judgeable
Zeldain GardenSum the number of divisors of every integer from N to M, where N and M can reach 10^12.	Hard8	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Light Emitting HindenburgChoose K of N bitmask schedules to maximize the bitwise AND of their codes, reading the result as the group availability code.	Hard8	Bit manipulationGreedy+2	No attempts yet	1s	512 MB	Judgeable
Candles and ShadowsGiven a convex red polygon that contains a convex blue polygon, find the shadow area cast by the blue polygon for each candle position.	Hard8	GeometryBinary search+1	No attempts yet	1s	512 MB	Judgeable
Fraction CalculationGiven N sorted fractions in [0, 1) read as points on a circle, decide whether some N-point sequence has a larger total pairwise circular distance.	Hard8	MathSorting+1	No attempts yet	1s	512 MB	Judgeable
Twin Trees Bros.Given two 3D trees, count the node correspondences under which one tree maps onto the other by translation, uniform positive scaling, and axis rotations.	Hard8	TreeGeometry+1	No attempts yet	3s	512 MB	Judgeable
Sink the Billiard BallA point ball bounces off the edges of an A by B table with velocity (p,q); count edge hits until it reaches a corner, or print -1 if it never stops.	Hard8	MathNumber theory+2	No attempts yet	1s	256 MB	Judgeable
Who Has Not Read the Message?Given each message's sender and the count of people who had not read it, count the possible sets of unread people per message, modulo 1e9+7.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	1s	256 MB	Judgeable
Find The NumberGiven up to 12 department numbers, find the n-th positive integer divisible by exactly one of them, with n up to 2^31.	Hard8	MathBinary search+2	No attempts yet	1s	512 MB	Judgeable
MeetingsCows on a line swap velocities when they meet, stop at barns, and the question asks how many meetings occur before half the total weight has stopped.	Hard8	SortingMath+2	No attempts yet	1s	512 MB	Judgeable
Dramatic DuelGiven n carpet kinds and k stacked carpets, the task is to pick each carpet's orientation so the guide, who moves first, loses, or report that no such placement exists.	Hard8	Game theoryDynamic programming+1	No attempts yet	1s	512 MB	Judgeable
Coloring a Rectangle 2Count binary colorings of an N by M grid, N up to 1e18 and M at most 5, with no 2x2 block of a single color, modulo 1e9+7.	Hard8	Dynamic programmingMatrix+2	No attempts yet	1s	512 MB	Judgeable
Cave PaintingsCount modulo 1e9+7 the ways to fill empty cells of a bordered grid with water so that any lower-or-equal empty/water region reachable from a water cell is also water.	Hard8	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
Loan RepaymentFind the largest X so that paying floor((N-G)/X) milk per day, floored at M, clears N gallons within K days.	Hard8	Binary searchMath+2	No attempts yet	2s	512 MB	Judgeable