Problems

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Total results29,423 problems

Ones
Hard8
Number theory, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Similar Polygons
Hard8
Geometry, String matching+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Similar Polygons
Hard8
Geometry, String matching+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Robots
Hard8
BFS, Graph+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Toll
Hard8
Minimum spanning tree, Greedy+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Making test data 3
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Winter Roads
Hard8
Graph, Union-find+2
No attempts yet
Time limit
10s
Memory limit
128 MB
Judgeable
Can of Worms
Hard8
Sorting, Binary search+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Automatic Trading
Hard8
String, String matching+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Flooding Fields
Hard8
Dynamic programming, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Goat Ropes
Hard8
Graph, Minimum spanning tree+2
No attempts yet
Time limit
8s
Memory limit
128 MB
Judgeable
Conditional Statements
Hard8
Simulation, Implementation+2
No attempts yet
Time limit
10s
Memory limit
128 MB
Judgeable
Football
Hard8
Binary search, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
The Palindromes Strike Back
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Obstacle Course
Hard8
BFS, Simulation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Obstacle Course
Hard8
BFS, Simulation+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Dorm Party
Hard8
Graph, Dynamic programming+2
No attempts yet
Time limit
15s
Memory limit
1024 MB
Judgeable
Address Matching
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Number Square
Hard8
Backtracking, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Grand Tour
Hard8
Graph, Minimum spanning tree+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Electric Car
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Rocket
Hard8
Binary search, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Transformation from One
Hard8
Backtracking, BFS+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Robots
Hard8
Simulation, Intervals+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Unter
Hard8
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Coat Rack
Hard8
Dynamic programming, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Thieves
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Kortos
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Bouquet
Hard8
Dynamic programming, Combinatorics
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
ASM
Hard8
Brute force, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Cheap Flights
Hard8
Graph, Greedy+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Changing Phone Numbers
Hard8
String, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fortune at El Dorado
Hard8
Two pointers, Binary search+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Intercepting Missiles
Hard8
Geometry, Binary search+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fixing Codes
Hard8
Greedy, Tree+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Map Labeler
Hard8
Binary search, Geometry+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Blue x Red = Bang
Hard8
Geometry, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
JaWs
Hard8
Geometry, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Bermuda Triangle
Hard8
Backtracking, Geometry+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Puzzle Out
Hard8
Backtracking, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Willy Memorial Program
Hard8
Graph, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
University Entrance Examination
Hard8
Implementation, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Color Tunnels
Hard8
Geometry, Shortest path+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Museum Heist: Area of the Shadowy Regions
Hard8
Geometry, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Painting a Board
Hard8
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Crossed Matchings
Hard8
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Magazine Delivery
Hard8
Dynamic programming, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Erythea Campaign
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Farmland
Hard8
Graph, Geometry+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Order of Trees
Hard8
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Robots
Hard8
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Picnic Planning
Hard8
Graph, Minimum spanning tree+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Word Encoding
Hard8
Dynamic programming, String matching+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pseudo-random Numbers
Hard8
Math, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Chandelier
Hard8
Stack, Greedy
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Bring Them There
Hard8
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Data Mining
Hard8
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Farmer Bill's Problem
Hard8
Geometry, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Hypertransmission
Hard8
Sorting, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Jurassic Remains
Hard8
Bit manipulation, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Evacuation Plan
Hard8
Graph, Minimum spanning tree+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Inlay Cutters
Hard8
Geometry, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Statistical Trouble
Hard8
Implementation, Matrix+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Library
Hard8
Geometry, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Frontier
Hard8
Geometry, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fence
Hard8
Geometry, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Black Box
Hard8
Simulation, Brute force+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Consecutive Ones
Hard8
Graph, Implementation+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Ellipse
Hard8
Geometry, Math+2
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Incredible! Impossible!
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
The K-th Number
Hard8
Binary search, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Destroying the Graph
Hard8
Graph, Minimum spanning tree+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Experiment "X": Explosions Expected
Hard8
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Highways
Hard8
Greedy, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Jogging
Hard8
Shortest path, Geometry+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Key Insertion
Hard8
Union-find, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Platforms
Hard8
Dynamic programming, Sorting+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Lucky Tickets
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Robotic Invasion
Hard8
BFS, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Traveling Queen
Hard8
BFS, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
DNA Laboratory
Hard8
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Box Art
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Frog
Hard8
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Expressions
Hard8
Backtracking, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Lattice Points in the Union of Circles
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Missing Letters
Hard8
Dynamic programming, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Jury Compromise
Hard8
Dynamic programming, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Race
Hard8
Sorting, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Vote-Value Disparity 1
Hard8
Graph, Binary search+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Synchronization
Hard8
Union-find, Divide and conquer+2
No attempts yet
Time limit
8s
Memory limit
128 MB
Judgeable
Tree Similarity
Hard8
Dynamic programming, Tree+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Fish Catch
Hard8
Geometry, Binary search+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The (Bayesian) Hound and the Hare
Hard8
Probability, BFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Space Boomerang
Hard8
Math, Geometry+1
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Rectangles
Hard8
Segment tree, Sorting+1
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Spanning Tree
Hard8
Minimum spanning tree, Union-find+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
City Driving
Hard8
Tree, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Drunken Walk
Hard8
Graph, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Empty Triangles
Hard8
Geometry, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Identity Checker
Hard8
Math, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
OnesGiven p and n, count how many times 2 and 3 divide the repunit 1 + p + ... + p^(n-1) in base p.	Hard8	Number theoryMath	No attempts yet	1s	128 MB	Judgeable
Similar PolygonsDecide whether two polygons are similar, and if so print the square of the similarity factor as a reduced fraction and the matching vertex index in the second polygon.	Hard8	GeometryString matching+2	No attempts yet	1s	1024 MB	Judgeable
Similar PolygonsDecide whether two polygons are similar under rotation, reflection, translation, and scaling, then output the exact squared similarity ratio and the smallest matching vertex index.	Hard8	GeometryString matching+2	No attempts yet	1s	1024 MB	Judgeable
RobotsFind the minimum number of pushes to merge n robots (n <= 9) into one on a grid, where robots slide until blocked and plates turn them 90 degrees.	Hard8	BFSGraph+2	No attempts yet	2s	128 MB	Judgeable
TollA billionaire sets tolls on K new roads of his choosing so that the minimum spanning tree routing all traffic to town 1 maximizes his revenue, where K is at most 20.	Hard8	Minimum spanning treeGreedy+2	No attempts yet	3s	128 MB	Judgeable
Making test data 3Construct the lexicographically smallest SSSP test file (at most T integers) on which optimized Bellman-Ford finishes under C iterations but Floyd-Warshall exceeds C, or report that none exists.	Hard8	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
Winter RoadsAfter a series of road capacity updates, answer queries asking whether two landmarks stay connected using only roads of capacity at least w.	Hard8	GraphUnion-find+2	No attempts yet	10s	128 MB	Judgeable
Can of WormsFor each can, count how many cans explode when it is shot, following the chain reaction where each blast hits cans within its radius.	Hard8	SortingBinary search+2	No attempts yet	3s	128 MB	Judgeable
Automatic TradingGiven a string and pairs of positions, for each query find the length of the longest common prefix of the two suffixes starting at those positions.	Hard8	StringString matching+2	No attempts yet	5s	128 MB	Judgeable
Flooding FieldsGiven an n by n grid, k cows, and h hourly flood levels, find the maximum number of cows that can survive by moving each hour before the water rises.	Hard8	Dynamic programmingGraph+2	No attempts yet	1s	512 MB	Judgeable
Goat RopesAssign nonnegative radii to n points so that every pair satisfies r_i + r_j <= distance, and maximize the sum of all radii.	Hard8	GraphMinimum spanning tree+2	No attempts yet	8s	128 MB	Judgeable
Conditional StatementsParse a small nested if language, then for each checkpoint decide which variable assignments can reach it and print the forced true/false variables or unreachable.	Hard8	SimulationImplementation+2	No attempts yet	10s	128 MB	Judgeable
FootballSplit a row of N player skills into K consecutive segments of at least M each so that the minimum segment average is maximized, and print that value as a reduced fraction.	Hard8	Binary searchDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
The Palindromes Strike BackFor every position i, count the subsets of positions that include i and form a palindrome, then XOR all i times that count mod 1e9+7.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	2s	1024 MB	Judgeable
Obstacle CourseFind the minimum number of seconds to steer a sliding puck to a target on an ice rink, accelerating per second while avoiding integer-coordinate obstacles.	Hard8	BFSSimulation+2	No attempts yet	1s	1024 MB	Judgeable
Obstacle CourseTap a sliding puck to change its velocity and reach a target point in the fewest seconds without touching any axis-aligned obstacle stick.	Hard8	BFSSimulation+2	No attempts yet	2s	1024 MB	Judgeable
Dorm PartyGiven a bipartite interest graph, pick a minimum set of edges to dance so that no edge joins two undanced vertices.	Hard8	GraphDynamic programming+2	No attempts yet	15s	1024 MB	Judgeable
Address MatchingMatch each student address to a distinct teacher address with minimum total weighted edit distance, and among optimal matchings output the lexicographically smallest index sequence.	Hard8	Dynamic programmingGreedy+2	No attempts yet	3s	1024 MB	Judgeable
Number SquareFill an N x N Latin square with 1..N given some pre-filled cells and inequalities between neighboring cells, choosing the lexicographically smallest valid board.	Hard8	BacktrackingImplementation+2	No attempts yet	1s	1024 MB	Judgeable
Grand TourChoose a spanning subgraph from state roads (gaining their sale price) and private roads (paying their buy price) so that all cities stay connected, minimizing the net treasury cost.	Hard8	GraphMinimum spanning tree+2	No attempts yet	1s	1024 MB	Judgeable
Electric CarFind the minimum total time to drive from city 1 to city N, where each road costs 1 hour and L energy, and charging takes whole hours at rate c_i per city.	Hard8	GraphShortest path+2	No attempts yet	1s	1024 MB	Judgeable
RocketFind, for each rocket, the minimum fuel so its total climb with velocity floor(K/(M+T))-g reaches at least the target height H.	Hard8	Binary searchMath+1	No attempts yet	1s	1024 MB	Judgeable
Transformation from OneStarting from 1, you may add 1 to the first or last digit for cost 1, or multiply it by 2..9 for cost 2; find the minimum cost to reach each given number, or -1.	Hard8	BacktrackingBFS+2	No attempts yet	1s	1024 MB	Judgeable
RobotsRobots on a circular track move clockwise for given durations, pushing each other and stopping at walls; find each final position.	Hard8	SimulationIntervals+2	No attempts yet	1s	1024 MB	Judgeable
UnterA connected graph with N houses and exactly N edges (one cycle) must answer up to 1e6 shortest distance queries.	Hard8	GraphDFS+2	No attempts yet	1s	1024 MB	Judgeable
Coat RackSort garments and targets; sliding garments keeps their order and may stack them, so assign each target to a position minimizing total distance under order constraints.	Hard8	Dynamic programmingDivide and conquer+2	No attempts yet	1s	1024 MB	Judgeable
ThievesGiven a tree with K robbed cities, block some cities at cost a_i so that the reachable set of cities from the robbed nodes through unblocked cities is minimized in total cost (blocking plus M per searched city).	Hard8	TreeDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
KortosCount the distinct ordered piles a player can build from N distinct cards where each new card matches the top card's number, or matches its suit with a larger number, modulo 1e9+7.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	2s	1024 MB	Judgeable
BouquetCount distinct flower sequences a robot can collect moving left, right, or down, picking at least one flower per floor, modulo 1e9+7.	Hard8	Dynamic programmingCombinatorics	No attempts yet	1s	1024 MB	Judgeable
ASMFind the fewest add/multiply/print commands in a one-variable program whose printed concatenation matches every test's required output.	Hard8	Brute forceDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
Cheap FlightsGiven a weighted graph, pick a set of edges with pairwise nonempty intersection maximizing total weight.	Hard8	GraphGreedy+2	No attempts yet	2s	1024 MB	Judgeable
Changing Phone NumbersGiven area codes and a sequence of rules (digit duplication, digit swap, area-code change) applied over time, answer queries transforming a phone number from one year to another.	Hard8	StringSimulation+2	No attempts yet	1s	128 MB	Judgeable
Fortune at El DoradoGiven up to 1000 points on a 1000x1000 grid and a maximum area A, find an axis-parallel rectangle with positive integer area at most A containing the most points.	Hard8	Two pointersBinary search+2	No attempts yet	1s	128 MB	Judgeable
Intercepting MissilesGiven moving bombers and passenger planes plus fixed missile launchers, find the maximum number of bombers that can be shot down without hitting any passenger plane.	Hard8	GeometryBinary search+2	No attempts yet	1s	128 MB	Judgeable
Fixing CodesGiven a prefix-free code and a new binary string, find the minimum total number of bits to append so the whole multiset becomes prefix-free again.	Hard8	GreedyTree+2	No attempts yet	1s	128 MB	Judgeable
Map LabelerGiven city points in the plane, find the largest square label size so that each label has its city at the midpoint of its top or bottom edge and no two label interiors overlap.	Hard8	Binary searchGeometry+2	No attempts yet	1s	128 MB	Judgeable
Blue x Red = BangGiven up to nine blue and nine red points, decide whether a simple blue polygon and a simple red polygon can be drawn with disjoint interiors and boundaries.	Hard8	GeometryBrute force+2	No attempts yet	1s	128 MB	Judgeable
JaWsGiven two rows of equilateral triangles, drop the upper row onto the lower one and report where it settles or which side it slides off.	Hard8	GeometrySimulation+1	No attempts yet	1s	128 MB	Judgeable
The Bermuda TriangleGiven a regular hexagon of side s and allowed equilateral triangle sizes, decide whether the hexagon can be tiled exactly by triangles of those sizes.	Hard8	BacktrackingGeometry+2	No attempts yet	1s	128 MB	Judgeable
Puzzle OutGiven a dictionary and an encrypted uppercase text, recover the substitution cipher table or report no solution or multiple solutions.	Hard8	BacktrackingHash map+2	No attempts yet	1s	128 MB	Judgeable
The Willy Memorial ProgramSimulate water filling interconnected vertical pipes through links and find when the level in a target pipe is reached.	Hard8	GraphSimulation+1	No attempts yet	1s	128 MB	Judgeable
University Entrance ExaminationGiven students with scores, home regions, and program preference lists, plus program capacities, assign students to programs under a local-region priority rule and a fairness rule.	Hard8	ImplementationGreedy+2	No attempts yet	1s	128 MB	Judgeable
Color TunnelsGiven a color sequence and colored line-segment tunnels, find the shortest path from source to destination that traverses tunnels in the required color order.	Hard8	GeometryShortest path+1	No attempts yet	1s	128 MB	Judgeable
Museum Heist: Area of the Shadowy RegionsGiven an axis-aligned rectangle with non-overlapping rectilinear polygonal obstacles and a gun at the upper-right corner, find the total area of points no monotone beam can reach.	Hard8	GeometrySimulation+2	No attempts yet	1s	128 MB	Judgeable
Painting a BoardGiven up to 15 rectangles with colors and vertical precedence constraints, find the minimum number of brush pick-ups to paint every rectangle.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	1s	128 MB	Judgeable
Crossed MatchingsGiven two rows of positive integers, draw the maximum number of equal-value matching segments between the rows so that each segment crosses exactly one other and no number is used twice.	Hard8	Dynamic programmingArray+2	No attempts yet	1s	128 MB	Judgeable
Magazine DeliveryThree cars start at L1 and must deliver to locations in strict order 2,3,...,N, with only one car moving at a time; minimize the total completion time.	Hard8	Dynamic programmingShortest path+2	No attempts yet	1s	128 MB	Judgeable
The Erythea CampaignOn an m by n grid with blocked stronghold cells, each grid intersection has risk m+n minus its shortest distance to a stronghold boundary; find the minimum-risk grid-line path from S to D.	Hard8	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
FarmlandGiven a planar graph of farming regions, count the proper regions bounded by a simple cycle with no interior vertices or edges and exactly k boundary edges.	Hard8	GraphGeometry+2	No attempts yet	1s	128 MB	Judgeable
Order of TreesGiven n, print the n-th binary tree under a canonical ordering by node count and by (left subtree number, right subtree number) recursively.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
RobotsSimulate a 31x31 robot game where robots chase you, applying a tie-broken greedy movement and teleport strategy to report whether you win or lose.	Hard8	SimulationImplementation+2	No attempts yet	1s	128 MB	Judgeable
Picnic PlanningFind a minimum-cost set of car routes so every brother reaches Park, with at most s cars parked there.	Hard8	GraphMinimum spanning tree+2	No attempts yet	1s	128 MB	Judgeable
Word EncodingGiven up to 1000 forbidden substrings of length 1 to 3, rank valid words by length then alphabetically; answer queries converting a word to its index and an index to its word.	Hard8	Dynamic programmingString matching+2	No attempts yet	1s	128 MB	Judgeable
Pseudo-random NumbersGiven the first L digits of a pseudo-random sequence generated by repeatedly summing adjacent base-B digits, decide whether the T-th element is forced, or report impossible or unpredictable.	Hard8	MathImplementation+2	No attempts yet	1s	128 MB	Judgeable
ChandelierGiven a valid stack program that builds a chandelier, find the minimum stack capacity needed to build an identical chandelier, where ring children may be rotated cyclically.	Hard8	StackGreedy	No attempts yet	2s	128 MB	Judgeable
Bring Them ThereFind the minimum number of days to send K ships from S to T through an undirected graph where each edge carries at most one ship per day.	Hard8	GraphBFS+2	No attempts yet	2s	128 MB	Judgeable
Data MiningChoose non-negative shifts A and B so the floor formula for Q's offsets packs N records of size S_Q without overlap, minimizing the required K, then A, then B.	Hard8	MathNumber theory+2	No attempts yet	1s	128 MB	Judgeable
Farmer Bill's ProblemPlace non-overlapping, non-touching rectangles inside a rectangular field so all given circles lie within them, minimizing total rectangle area, and output the remaining harvestable area.	Hard8	GeometryDynamic programming+2	No attempts yet	2s	128 MB	Judgeable
HypertransmissionGiven N points in 3D each labeled 0 or 1, choose a squared radius R^2 to maximize the number of points where opposite-label neighbors outnumber same-label ones, then report that maximum and the smallest R^2 achieving it.	Hard8	SortingPrefix sum+2	No attempts yet	1s	128 MB	Judgeable
Jurassic RemainsEach bone is a set of letters; choose the largest subset such that every letter appearing in it occurs in at least two of the chosen bones.	Hard8	Bit manipulationBrute force+2	No attempts yet	1s	128 MB	Judgeable
Evacuation PlanGiven buildings with worker counts, shelters with capacities, and a valid assignment plan, decide whether the plan minimizes total Manhattan-plus-one travel time over all valid plans.	Hard8	GraphMinimum spanning tree+2	No attempts yet	1s	128 MB	Judgeable
Inlay CuttersCount all 45-degree right isosceles triangles formed by grid-aligned cuts and diagonals on an M by N plate after K straight cuts.	Hard8	GeometryImplementation+2	No attempts yet	1s	128 MB	Judgeable
Statistical TroubleOutput each cross table of two survey questions as raw counts and rounded row and column percentages in a fixed 6-character grid.	Hard8	ImplementationMatrix+2	No attempts yet	1s	128 MB	Judgeable
LibraryGiven shelf and peg geometry in a niche, find a redesign that seats a fixed tome on one shelf while minimizing pegs moved and plank cut.	Hard8	GeometryBrute force+2	No attempts yet	1s	128 MB	Judgeable
FrontierChoose a subset of the polygon's vertices, in clockwise order, forming a convex polygon that strictly contains all given points, minimizing its perimeter.	Hard8	GeometryDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
FenceCompute the total illumination reaching the lit parts of a polygonal fence from a point lamp, accounting for shadows and the cosine obliquity factor.	Hard8	GeometryImplementation+2	No attempts yet	1s	128 MB	Judgeable
Black BoxFind all 6x6 atom placements inside an 8x8 box that reproduce a set of laser entry and exit experiments, and report the layout if it is unique.	Hard8	SimulationBrute force+2	No attempts yet	2s	1024 MB	Judgeable
Consecutive OnesPermute the columns of a 0-1 matrix so that the 1s in every row are consecutive, with column 0 fixed as the first column.	Hard8	GraphImplementation+2	No attempts yet	2s	1024 MB	Judgeable
EllipseGiven five integer points, either report that no unique ellipse passes through them or compute that ellipse's area to six decimals.	Hard8	GeometryMath+2	No attempts yet	2s	64 MB	Judgeable
Incredible! Impossible!Count n by 3 tables of non-negative integers with given row sums and column sums, modulo 10 to the 17.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	2s	64 MB	Judgeable
The K-th NumberGiven an array of distinct integers and m range queries, return the k-th smallest value inside each queried subarray.	Hard8	Binary searchDivide and conquer+2	No attempts yet	1s	256 MB	Judgeable
Destroying the GraphFind the minimum cost to cover every arc of a directed graph by choosing, for each vertex, to delete its incoming or outgoing arcs.	Hard8	GraphMinimum spanning tree+2	No attempts yet	1s	512 MB	Judgeable
Experiment "X": Explosions ExpectedCount valid mixtures (at most S total ounces, at least two ingredients used) that are not dominated coordinatewise by any of M given exploding mixtures, modulo nothing.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
HighwaysGiven N cities on a line with one-way roads only left to right, add two non-touching one-way roads to make the network strongly connected at minimum total length, or print 0.	Hard8	GreedyImplementation+2	No attempts yet	1s	512 MB	Judgeable
JoggingGiven N pairs of one-way moving walkway lines in the plane with boarding and leaving costs, find the minimum travel time from house to office where walking off-line is allowed.	Hard8	Shortest pathGeometry+2	No attempts yet	1s	512 MB	Judgeable
Key InsertionSimulate the recursive Insert operation on an infinite array for N keys and print the final occupancy up to the largest filled cell.	Hard8	Union-findImplementation+2	No attempts yet	1s	512 MB	Judgeable
PlatformsGiven points with distinct x, find the longest chain of flights where each next point has larger x and no larger y, then report every point lying on some longest chain.	Hard8	Dynamic programmingSorting+2	No attempts yet	2s	128 MB	Judgeable
Lucky TicketsCount lucky n-digit numbers among k consecutive values starting at a uniformly random s in [a,b], and print the expected count as a fraction.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	1s	128 MB	Judgeable
Robotic InvasionEdit as few commands as possible in a movement string so the robot reaches a trap, breaking ties by earliest capture and then lexicographic order.	Hard8	BFSDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
Traveling QueenFind a shortest sequence of queen moves that visits every knight, then ends next to the bishop, and among shortest paths print the lexicographically smallest.	Hard8	BFSBit manipulation+2	No attempts yet	2s	128 MB	Judgeable
DNA LaboratoryGiven up to 15 DNA strings, find the shortest string that contains all of them as substrings, breaking ties by lexicographic order.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	1s	128 MB	Judgeable
Box ArtGiven a bounding box and up to 2000 axis-aligned boxes, compute the volume of their union clipped to the bounding box.	Hard8	GeometrySorting+2	No attempts yet	1s	128 MB	Judgeable
FrogGiven axis-aligned non-touching squares in the first quadrant and a jump reach d, find the largest x+y over squares reachable from the square at the origin.	Hard8	GraphBFS+2	No attempts yet	1s	128 MB	Judgeable
ExpressionsFor each range of digits and target, print every fully bracketed expression over the digits in order that evaluates to the target. (Note: summary must be one sentence, at most 160 chars.)	Hard8	BacktrackingRecursion+2	No attempts yet	1s	128 MB	Judgeable
Lattice Points in the Union of CirclesCount integer lattice points inside the union of up to 10,000 circles, restricted to the coordinate box from -16383 to 16384.	Hard8	GeometrySorting+2	No attempts yet	1s	128 MB	Judgeable
Missing LettersReconstruct a space-free corrupted string into words from a known vocabulary, choosing the highest-scoring word segmentation and breaking ties alphabetically.	Hard8	Dynamic programmingString+2	No attempts yet	1s	128 MB	Judgeable
Jury CompromisePick exactly m candidates minimizing the prosecution minus defence imbalance, breaking ties by the largest total value, then by lexicographically smallest candidate list.	Hard8	Dynamic programmingSorting+1	No attempts yet	1s	128 MB	Judgeable
The RaceCount all overtakes among spaceships with given starting positions and speeds, then list the first 10000 in time order.	Hard8	SortingGreedy+2	No attempts yet	1s	128 MB	Judgeable
Vote-Value Disparity 1Partition N connected provinces into K connected districts to minimize the ratio between the most and least powerful single vote.	Hard8	GraphBinary search+1	No attempts yet	1s	128 MB	Judgeable
SynchronizationGiven a tree whose edges toggle on and off over time, report how many distinct information pieces each queried server holds at the end.	Hard8	Union-findDivide and conquer+2	No attempts yet	8s	128 MB	Judgeable
Tree SimilarityGiven two ordered rooted trees, find the minimum number of node relabel, delete, and insert operations to turn the first tree into the second.	Hard8	Dynamic programmingTree+2	No attempts yet	3s	128 MB	Judgeable
Fish CatchGiven a fixed net center and N fish moving at constant velocity, find the smallest radius that catches at least K fish at some time t >= 0.	Hard8	GeometryBinary search+1	No attempts yet	1s	128 MB	Judgeable
The (Bayesian) Hound and the HareMaintain a Bayesian belief over a hare's random-walk position, apply noisy observations, and greedily move the hound to the cell with least expected maze distance.	Hard8	ProbabilityBFS+2	No attempts yet	1s	128 MB	Judgeable
Space BoomerangGiven M direction vectors in N-dimensional space, find every vector that cannot appear with a nonzero coefficient in any linear combination summing to zero.	Hard8	MathGeometry+1	No attempts yet	3s	128 MB	Judgeable
RectanglesGiven N axis-aligned rectangles, compute the area of their union.	Hard8	Segment treeSorting+1	No attempts yet	3s	128 MB	Judgeable
Spanning TreeCount the minimum spanning trees of a connected weighted multigraph modulo 1000003, where any weight class has at most 4 edges.	Hard8	Minimum spanning treeUnion-find+1	No attempts yet	1s	128 MB	Judgeable
City DrivingIn a connected graph with N nodes and N edges, answer many shortest-path queries between pairs of nodes.	Hard8	TreeGraph+2	No attempts yet	1s	128 MB	Judgeable
Drunken WalkIn a weighted DAG, remove at most one edge to maximize the expected number of edges walked from vertex 0 before reaching a sink.	Hard8	GraphDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Empty TrianglesGiven N lines with no three concurrent, count the triangles whose interior is not crossed by any other line.	Hard8	GeometryCombinatorics+1	No attempts yet	2s	512 MB	Judgeable
Identity CheckerEach test case gives a reverse Polish expression in x with sin, cos, and tan; decide whether it equals zero wherever defined.	Hard8	MathString+2	No attempts yet	1s	128 MB	Judgeable