Problems

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Total results29,425 problems

Unchanged Picture
Hard8
Geometry, String matching+1
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Ardenia
Hard8
Geometry, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Insults
Hard8
String, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Phone Cell
Hard8
Geometry, Brute force+1
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Hexagonal Parcels
Hard8
Graph, BFS+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ants
Hard8
Segment tree, Prefix sum+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Bundling
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Shortcut
Hard8
Geometry, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
November Rain
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Soccer Ball
Hard8
Geometry, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Minimizing Maximizer
Hard8
Greedy, Intervals+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Choir
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Horizontally Visible Segments
Hard8
Sorting, Geometry+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Direct Visibility
Hard8
BFS, Geometry+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Run Away
Hard8
Geometry, Binary search+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Flights
Hard8
Geometry, Segment tree+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
The GCD Guessing Game
Hard8
Number theory, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Interactive Permutation Guessing
Hard8
Implementation, Binary search+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Journey
Hard8
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Immediate Delivery
Hard8
Bit manipulation, Dynamic programming+2
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
King of Operations
Hard8
Dynamic programming, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cactus Revolution
Hard8
Graph, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Dome of the Circus
Hard8
Binary search, Geometry+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Factorial Simplification
Hard8
Math, Number theory+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bug2 Path Length
Hard8
Geometry, Simulation+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Frames
Hard8
Geometry, Math+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Gadgets Factory
Hard8
Math, Binary search+2
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Journey
Hard8
Shortest path, Dynamic programming+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Funny Language
Hard8
Combinatorics, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Garbling Game
Hard8
Simulation, Matrix+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
K-equivalence
Hard8
Math, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Four Points
Hard8
Geometry, Math+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Image Recognition
Hard8
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Aerodynamics
Hard8
Geometry, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Exclusive Access
Hard8
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Just Too Lucky
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Fund Management
Hard8
Dynamic programming, Simulation+1
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Japanese Writing
Hard8
Graph, Backtracking+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Cross and Cross
Hard8
Game theory, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Domestic Networks
Hard8
Minimum spanning tree, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Repetition-Free Formula
Hard8
Recursion, String+2
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Billing Tables
Hard8
Trie, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Driving Directions
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Graveyard
Hard8
Math, Geometry+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Team Difficulty
Hard8
Graph, Binary search+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Interconnect
Hard8
Union-find, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bridges
Hard8
Tree, Greedy+2
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Confectionery
Hard8
Simulation, Math+1
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Feng Shui
Hard8
Geometry, Binary search+1
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Sangbeom's Picture Frame
Hard8
Graph, Greedy+1
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Security Guard Staffing
Hard8
Math, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hardwood Cutting
Hard8
Simulation, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Knockdown
Hard8
Geometry, Binary search+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bee Garden
Hard8
Tree, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Inner Vertices
Hard8
Geometry, Simulation+1
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
The Admiral
Hard8
Shortest path, Graph+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bicycle
Hard8
Simulation, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tournament Manipulation
Hard8
Backtracking, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Interesting Set
Hard8
Number theory, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Train Delays
Hard8
Shortest path, Dynamic programming+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Dividing the Gems
Hard8
Greedy, Game theory+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hill Drive
Hard8
Binary search, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Final Rankings
Hard8
Graph, Topological sort+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Selling Land
Hard8
Dynamic programming, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Telephone Network
Hard8
Graph, Greedy+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Wormly
Hard8
Greedy, Two pointers+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sculpture
Hard8
Geometry, Matrix+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Rafting Design
Hard8
Geometry, Binary search+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Flight Safety
Hard8
Geometry, Binary search+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Peaks
Hard8
Union-find, Sorting+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Walking
Hard8
Geometry, Graph+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ticket to Ride
Hard8
Graph, Minimum spanning tree+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pesky Heroes
Hard8
Tree, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Secret Code: Largest Number
Hard8
Dynamic programming, String matching+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Term Generator
Hard8
String matching, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Painting
Hard8
Graph, BFS+1
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
The Largest Circle
Hard8
Binary search, Geometry+1
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Programming Contests
Hard8
Bit manipulation, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cosmic Station
Hard8
Tree, Graph+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Proof Generator
Hard8
String matching, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Software Industry Revolution
Hard8
String matching, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Products
Hard8
Number theory, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Payment System
Hard8
Math, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Maximum Value
Hard8
Math, Greedy+1
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
"Shortest" Pair of Paths
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Lord of the Ring
Hard8
Backtracking, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Beer Land
Hard8
Combinatorics, Geometry+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Art Gallery
Hard8
Geometry, Divide and conquer+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Beehives
Hard8
Graph, Union-find+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
ACGU
Hard8
Dynamic programming, String+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Old School Days
Hard8
Math, Combinatorics+1
No attempts yet
Time limit
10s
Memory limit
128 MB
Judgeable
Sliding Block Puzzle
Hard8
BFS, Graph+1
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Company Organization
Hard8
Union-find, Graph+1
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Alphabet Soup
Hard8
Combinatorics, Math+1
No attempts yet
Time limit
10s
Memory limit
128 MB
Judgeable
Coin Collecting
Hard8
Union-find, Greedy+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Cyber Donut Crime Investigation
Hard8
Divide and conquer, Binary search+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Perfect Square Republic
Hard8
Number theory, Math+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Palindromic DNA
Hard8
Union-find, Graph+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Jumping Monkey
Hard8
BFS, Graph+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Light Bulb Game
Hard8
Combinatorics, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Unchanged PictureDetermine whether two plotter-drawn vector pictures are geometrically similar under translation, rotation, and uniform scaling but no mirroring.	Hard8	GeometryString matching+1	No attempts yet	5s	128 MB	Judgeable
ArdeniaGiven two 3D segments per test case (up to 1e5), compute the exact squared minimum distance between them as a reduced fraction.	Hard8	GeometryMath+1	No attempts yet	1s	128 MB	Judgeable
InsultsParse a string against a context-free grammar defining insults, then find the lexicographically next same-length valid insult or report invalid/ultimate.	Hard8	StringDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
Phone CellGiven N up to 2000 points and a radius R, find the maximum number of points that a single circle of radius R can simultaneously cover.	Hard8	GeometryBrute force+1	No attempts yet	5s	128 MB	Judgeable
Hexagonal ParcelsOn a hexagonal grid with four labeled connected regions, find the minimum number of free cells to buy so all four regions become one connected component (Steiner-tree style optimization on a hex graph).	Hard8	GraphBFS+1	No attempts yet	1s	128 MB	Judgeable
AntsGiven a forest of towns formed by persistent range-add copies of parent towns, answer range-sum queries on each newly created version using online, XOR-derived parameters that depend on previous answers.	Hard8	Segment treePrefix sum+2	No attempts yet	3s	128 MB	Judgeable
BundlingGiven permitted bundle templates and a dependency chain among instructions, compute the minimum number of bundles to pack the sequence and, among those, the minimum number of stops needed.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	128 MB	Judgeable
ShortcutGiven a self-avoiding grid walk of unit segments, find the shortest horizontal or vertical connector between two visited break points that is not already part of the path, with tie-breaking rules.	Hard8	GeometryHash map+2	No attempts yet	1s	128 MB	Judgeable
November RainGiven non-intersecting sloped roof segments, compute for each segment how much rainwater (falling vertically, then sliding down slopes and shielded by segments above) drains off its lower end.	Hard8	GeometrySorting+1	No attempts yet	1s	128 MB	Judgeable
Soccer BallGiven per-vertex counts of green panels touching each vertex of a simple closed loop drawn on a truncated icosahedron soccer ball, determine how many of the 12 pentagons, 20 hexagons end up black, white, or green.	Hard8	GeometryMath+1	No attempts yet	1s	128 MB	Judgeable
Minimizing MaximizerGiven a pipeline of range-sort operations, find the minimum number of operations (kept in order) whose composition still guarantees the last position always holds the overall maximum.	Hard8	GreedyIntervals+1	No attempts yet	1s	512 MB	Judgeable
ChoirCompute minimum-cost assignment of singers to positions between all song pairs, then find the song ordering (TSP over at most 6 songs) that minimizes total replacements.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	3s	512 MB	Judgeable
Horizontally Visible SegmentsGiven disjoint vertical segments, count triangles formed by triples that are pairwise horizontally visible using a sweep and visibility structure.	Hard8	SortingGeometry+1	No attempts yet	1s	128 MB	Judgeable
Direct VisibilityFind the shortest grid path with step-height limits between two towers where after every step at least one tower stays visible over 3D terrain, using BFS combined with 3D line-of-sight visibility checks.	Hard8	BFSGeometry+1	No attempts yet	1s	128 MB	Judgeable
Run AwayGiven a rectangle and up to 1000 points inside it, find the point in the rectangle maximizing the minimum distance to the points and output that squared distance as a reduced fraction.	Hard8	GeometryBinary search+1	No attempts yet	1s	128 MB	Judgeable
FlightsFor each query, find the maximum altitude among a subset of parabolic missile trajectories (indexed by launch time) restricted to a horizontal range, and output the exact reduced fraction.	Hard8	GeometrySegment tree+2	No attempts yet	3s	1024 MB	Judgeable
The GCD Guessing GameGiven n, find the minimum worst-case number of GCD queries needed to uniquely identify a hidden number between 1 and n using adaptive gcd questions.	Hard8	Number theoryMath+1	No attempts yet	1s	128 MB	Judgeable
Interactive Permutation GuessingGuess a hidden permutation of size n up to 40 by asking for the LCS length with chosen permutations, using at most 5n^2 queries.	Hard8	ImplementationBinary search+1	No attempts yet	1s	128 MB	Judgeable
JourneySimulate a robot following recursive turtle-graphics functions with possible infinite recursion or unbounded movement, and output the maximum Manhattan distance from origin or detect Infinity.	Hard8	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
Immediate DeliveryGiven a small weighted graph (n ≤ 18), split all junctions between two drivers starting from node 1 so that the larger of their two walk-covering times from node 1 is minimized.	Hard8	Bit manipulationDynamic programming+2	No attempts yet	3s	256 MB	Judgeable
King of OperationsGiven a custom digit-wise binary operator table, compute the repeated left-to-right combination of all numbers from a to b (up to 10^18) using digit dynamic programming per digit position.	Hard8	Dynamic programmingMath+1	No attempts yet	1s	128 MB	Judgeable
Cactus RevolutionDecide whether a given cactus graph can be split into k connected districts of equal size n/k, using cactus structure properties.	Hard8	GraphDynamic programming+1	No attempts yet	1s	128 MB	Judgeable
Dome of the CircusGiven 3D points, find the minimum-volume cone with apex on the z-axis and base on the ground plane that contains all points, then output its height and radius.	Hard8	Binary searchGeometry+1	No attempts yet	1s	128 MB	Judgeable
Factorial SimplificationGiven a ratio of products of factorials, determine if it is an integer and greedily decompose it into a canonical product of factorial powers with maximal bases and exponents in order.	Hard8	MathNumber theory+1	No attempts yet	1s	128 MB	Judgeable
Bug2 Path LengthSimulate the Bug2 robot navigation algorithm over rectilinear polygon obstacles and compute the total length of the traced path from start to finish.	Hard8	GeometrySimulation+1	No attempts yet	3s	256 MB	Judgeable
FramesGiven two axis-aligned picture frames (outer rectangle minus inner rectangle), find the translation of the second frame maximizing the intersection area with the first.	Hard8	GeometryMath+1	No attempts yet	3s	256 MB	Judgeable
Gadgets FactoryGiven m sorted factories each producing one of n part types, find all coordinates t minimizing the sum over parts of squared distance to the nearest factory of that part, expressed as exact fractions.	Hard8	MathBinary search+2	No attempts yet	3s	256 MB	Judgeable
JourneyGiven two graphs with shortest distances to a target node, find the longest alternating walk where each move strictly decreases the current graph's distance-to-target value, or report infinite.	Hard8	Shortest pathDynamic programming+1	No attempts yet	3s	256 MB	Judgeable
Funny LanguageChoose n new words (avoiding the given m words) to maximize the total count of formable-subword matches across all given words, using their letter multisets.	Hard8	CombinatoricsGreedy+1	No attempts yet	1s	128 MB	Judgeable
Garbling GameSimulate a periodic matrix-rotation process driven by a garbling map for up to 10^100 turns and count how many times each value is written, modulo 10^5.	Hard8	SimulationMatrix+1	No attempts yet	1s	128 MB	Judgeable
K-equivalenceGiven a finite set K of positive integers described as disjoint intervals, determine which decimal digits 1-9 can always be swapped in any number of K without leaving K, and output the resulting equivalence classes.	Hard8	MathSimulation+1	No attempts yet	1s	128 MB	Judgeable
Four PointsGiven four fixed points, decide whether a square exists such that each side contains exactly one of the points, none at a corner.	Hard8	GeometryMath+1	No attempts yet	3s	256 MB	Judgeable
Image RecognitionDesign an optimal decision program for a robot that moves on a grid and reads pixel colors to identify which of d given images it starts on, minimizing worst-case movement steps.	Hard8	BFSGraph+2	No attempts yet	1s	128 MB	Judgeable
AerodynamicsGiven points in 3D, build the convex hull and output the exact rational area of its cross-section polygon for every integer z between two bounds.	Hard8	GeometryMath+1	No attempts yet	2s	128 MB	Judgeable
Exclusive AccessGiven two threads of branching pseudo-code over three shared bits, decide whether every legal schedule satisfies mutual exclusion, deadlock freedom, and starvation freedom.	Hard8	GraphBFS+2	No attempts yet	2s	128 MB	Judgeable
Just Too LuckyCount integers from 1 to n (up to 10^12) whose value is divisible by its own digit sum, requiring digit-DP over fixed digit-sum targets.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	3s	256 MB	Judgeable
Fund ManagementGiven daily prices for up to 8 stocks over up to 100 days, decide one buy/sell/hold action per day under per-stock and total lot caps to maximize final cash after closing all positions.	Hard8	Dynamic programmingSimulation+1	No attempts yet	3s	128 MB	Judgeable
Japanese WritingDetermine whether each of several stroke-based hieroglyph writings is isomorphic to a reference writing, preserving stroke directions and pairwise endpoint directions among all 8 compass directions.	Hard8	GraphBacktracking+1	No attempts yet	2s	128 MB	Judgeable
Cross and CrossFor a 1×n board where players alternately mark cells and the first to make three consecutive marks wins, decide the winner under optimal play for given n up to 2000.	Hard8	Game theoryDynamic programming+1	No attempts yet	1s	128 MB	Judgeable
Domestic NetworksChoose a spanning tree of apartments and assign each edge to one of two cable types with limited total lengths to minimize cost, or report impossibility.	Hard8	Minimum spanning treeDynamic programming+1	No attempts yet	2s	64 MB	Judgeable
Repetition-Free FormulaParse a Boolean formula that may repeat variables, determine if the underlying function is read-once, and if so print its canonical repetition-free formula.	Hard8	RecursionString+2	No attempts yet	2s	64 MB	Judgeable
Billing TablesGiven an ordered old billing table with range-based prefix rules, build the minimal prefix-only dictionary table (no prefix a prefix of another) that reproduces exactly the same plan decisions for all 11-digit numbers.	Hard8	TrieGreedy+2	No attempts yet	1s	128 MB	Judgeable
Driving DirectionsFind the shortest path for a circle of radius r between two points avoiding axis-aligned rectangular obstacles, using tangent lines and arcs around inflated corners.	Hard8	GraphShortest path+1	No attempts yet	1s	128 MB	Judgeable
GraveyardGiven n equally spaced statues on a circle of length 10000 and m statues to add, find the minimum total sliding distance to reach n+m equally spaced positions with optimal rotation and assignment.	Hard8	MathGeometry+1	No attempts yet	1s	128 MB	Judgeable
Team DifficultyGiven a graph, find a subset of vertices maximizing the ratio of induced edges to vertices, output as a reduced fraction, which requires a max-density subgraph technique via binary search and max-flow.	Hard8	GraphBinary search+1	No attempts yet	1s	128 MB	Judgeable
InterconnectGiven an initial graph on up to 30 towns, compute the exact expected number of random-edge additions needed until the graph becomes fully connected, as a reduced fraction.	Hard8	Union-findMath+2	No attempts yet	1s	128 MB	Judgeable
BridgesChoose k edges of a weighted tree to convert to a faster speed so that the sum of travel times over all pairs is minimized, breaking ties lexicographically.	Hard8	TreeGreedy+2	No attempts yet	2s	64 MB	Judgeable
ConfectionerySimulate a leaking vertical tube with layered syrups, cracks, and a bottom hole, computing the exact rational volume of each syrup that ultimately reaches the mixer.	Hard8	SimulationMath+1	No attempts yet	2s	64 MB	Judgeable
Feng ShuiPlace two fixed-radius disks inside a convex polygon to maximize the area of their union, computing an exact geometric optimum.	Hard8	GeometryBinary search+1	No attempts yet	2s	64 MB	Judgeable
Sangbeom's Picture FrameGiven rods joined at beads forming a multigraph, find the minimum number of bead-removal and rod-joining actions to merge everything into one simple closed loop using all rods.	Hard8	GraphGreedy+1	No attempts yet	2s	64 MB	Judgeable
Security Guard StaffingGiven per-shift minimum guard requirements for workday daylight, weekend daylight, and nighttime shifts, find the minimum total number of guards across four fixed cyclic shift schedules to meet all coverage constraints simultaneously.	Hard8	MathCombinatorics+1	No attempts yet	1s	128 MB	Judgeable
Hardwood CuttingGiven a labeled grid board, compute the maximum number of pieces separable by straight guillotine-style cuts starting from exposed edges, accounting for pieces that interlock and cannot be separated.	Hard8	SimulationRecursion+2	No attempts yet	1s	128 MB	Judgeable
KnockdownGiven up to 20 points on a unit sphere, compute the minimal covering radius such that balls of that geodesic radius centered at the points cover the whole sphere.	Hard8	GeometryBinary search+1	No attempts yet	1s	128 MB	Judgeable
Bee GardenGiven a tree of hives with coordinates, find which single new edge added minimizes the doubled-tree traversal, i.e. maximizes edge weight removed twice minus new edge distance, tie-broken lexicographically.	Hard8	TreeDynamic programming+1	No attempts yet	2s	64 MB	Judgeable
Inner VerticesGiven initial black points on an infinite grid, simulate a closure process filling row/column-enclosed points and count final black vertices or detect non-termination.	Hard8	GeometrySimulation+1	No attempts yet	2s	64 MB	Judgeable
The AdmiralFind two vertex- and edge-disjoint (except at endpoints) directed paths from node 1 to node v in a weighted graph minimizing total edge weight, which requires a min-cost flow formulation with vertex splitting.	Hard8	Shortest pathGraph+1	No attempts yet	1s	128 MB	Judgeable
BicycleGiven a max-acceleration bicycle model with several periodic red-green traffic lights along a line, compute the earliest arrival time at a fixed destination.	Hard8	SimulationGreedy+1	No attempts yet	1s	128 MB	Judgeable
Tournament ManipulationGiven head-to-head results for n teams (n up to 8) with a guaranteed property for team 1, construct the lexicographically smallest single-elimination bracket where team 1 becomes champion.	Hard8	BacktrackingGreedy+1	No attempts yet	1s	128 MB	Judgeable
Interesting SetGiven a range [a,b], find the minimum-product square-forming subset using squarefree factorization and linear algebra over GF(2) plus meet-in-the-middle/graph reasoning.	Hard8	Number theoryMath+2	No attempts yet	1s	128 MB	Judgeable
Train DelaysGiven a train timetable with hourly departures and probabilistic delays, compute the minimum expected total travel time from start to destination as an exact fraction.	Hard8	Shortest pathDynamic programming+2	No attempts yet	5s	128 MB	Judgeable
Dividing the GemsSimulate an alternating gem-picking game where one player greedily picks by fixed rules while the other plays optimally to maximize his own total, tie-breaking for the opponent's total, and output final scores.	Hard8	GreedyGame theory+1	No attempts yet	1s	128 MB	Judgeable
Hill DriveGiven fuel and a per-road speed-dependent consumption model with a speed cap, choose speeds per road segment to minimize total travel time under a total fuel budget.	Hard8	Binary searchGreedy+1	No attempts yet	1s	128 MB	Judgeable
Final RankingsGiven last year's ranking and the set of team pairs whose relative order flipped, reconstruct this year's unique ranking or report ambiguity or contradiction.	Hard8	GraphTopological sort+1	No attempts yet	1s	256 MB	Judgeable
Selling LandFor every grid cell (as a rectangle's bottom-right corner), find the maximum perimeter of an all-grass rectangle ending there, then output counts grouped by perimeter.	Hard8	Dynamic programmingArray+1	No attempts yet	1s	128 MB	Judgeable
Telephone NetworkRoute m disjoint input-output requests through a recursive Clos-like network of binary switches, choosing at each layer the lexicographically smallest routing bit string.	Hard8	GraphGreedy+2	No attempts yet	2s	128 MB	Judgeable
WormlyFind the minimum number of moves to shift a worm's body window and its ordered legs across a bridge with missing planks, or report impossibility.	Hard8	GreedyTwo pointers+1	No attempts yet	1s	128 MB	Judgeable
SculptureGiven a set of axis-aligned boxes in 3D, compute the total exposed surface area and total volume, including internal cavities not reachable by liquid, using 3D space decomposition.	Hard8	GeometryMatrix+1	No attempts yet	1s	128 MB	Judgeable
Rafting DesignGiven an inner polygon fully enclosed by an outer polygon, compute the maximum radius of a circle that can travel all the way around the annular track between them without getting stuck.	Hard8	GeometryBinary search+1	No attempts yet	1s	128 MB	Judgeable
Flight SafetyGiven a flight polyline and continent polygons, compute the maximum over all points on the route of the minimum distance to any continent boundary or interior.	Hard8	GeometryBinary search+1	No attempts yet	1s	128 MB	Judgeable
PeaksCount grid cells that stay locally maximal when reachability is restricted to cells within height d of the starting cell, for many test cases up to 500x500.	Hard8	Union-findSorting+1	No attempts yet	2s	256 MB	Judgeable
WalkingGiven nested non-intersecting contour polygons on a plane, compute the minimum total ascent and descent along some path from one fixed point to another based on how many polygons of each height enclose the endpoints.	Hard8	GeometryGraph+1	No attempts yet	1s	128 MB	Judgeable
Ticket to RideGiven a weighted graph and four pairs of terminal cities, find the minimum total edge cost of a subgraph connecting all four pairs simultaneously.	Hard8	GraphMinimum spanning tree+2	No attempts yet	1s	128 MB	Judgeable
Pesky HeroesGiven a tree-like cave structure with orc traversal rules based on left/right turns and one allowed right-turn override, find the minimum number of gateways needed to reach all trap-free dead ends.	Hard8	TreeSimulation+1	No attempts yet	1s	128 MB	Judgeable
Secret Code: Largest NumberGiven a noisy string, find the largest decimal number it could decode to, either fixing one language for all digits or allowing a different language per digit, using digit-word subsequence matching.	Hard8	Dynamic programmingString matching+2	No attempts yet	3s	128 MB	Judgeable
Term GeneratorParse a formula, convert it to a normal form by expanding nested sums and products according to given rewriting rules, then implement a cyclic generator that outputs requested numbers of terms, some possibly skipped without printing, based on huge signed counters.	Hard8	String matchingRecursion+2	No attempts yet	1s	128 MB	Judgeable
PaintingGiven an n by n grid painted with k colors, find the minimum number of whole row or column repaints needed to make the entire grid one color, where a line can only be painted color c if it already has at least two tiles of that color, and list all colors achieving that minimum.	Hard8	GraphBFS+1	No attempts yet	5s	128 MB	Judgeable
The Largest CircleGiven N segments, find the maximum radius of a circle centered on the x-axis within [0,L] that touches but never crosses any segment, using binary search plus geometric distance checks.	Hard8	Binary searchGeometry+1	No attempts yet	5s	128 MB	Judgeable
Programming ContestsGiven problems that can each go to one of several named contests each needing a fixed count, find the maximum subset of contests that can be simultaneously fully staffed, requiring bitmask search combined with flow-style feasibility checks.	Hard8	Bit manipulationGraph+2	No attempts yet	1s	128 MB	Judgeable
Cosmic StationGiven all pairwise distances between leaves of a tree, determine the number of internal (branching) nodes.	Hard8	TreeGraph+1	No attempts yet	1s	128 MB	Judgeable
Proof GeneratorConvert a logical formula to a canonical disjunctive normal form using given rewrite rules, then cyclically output the k-th next satisfying terms under given axioms for a sequence of queries.	Hard8	String matchingRecursion+2	No attempts yet	1s	128 MB	Judgeable
Software Industry RevolutionGiven a wildcard pattern (with ? and *) and a text, find the minimum-complexity substring of the text that matches the whole pattern, or report impossible.	Hard8	String matchingDynamic programming+1	No attempts yet	1s	128 MB	Judgeable
ProductsFind the minimum count k of positive integers a1..ak such that the product of (ai+1) equals n times the product of ai.	Hard8	Number theoryMath+2	No attempts yet	1s	128 MB	Judgeable
Payment SystemGiven a huge account balance, construct a chain of numbers joined by exponentiation that stays within the left-to-right evaluated limit but maximizes the right-to-left (true) exponentiation value, breaking ties lexicographically.	Hard8	MathGreedy+2	No attempts yet	1s	128 MB	Judgeable
Maximum ValueGiven bounds and a fixed sum constraint on real numbers, compute the maximum possible sum of their p-th powers using a convexity-based extremal argument.	Hard8	MathGreedy+1	No attempts yet	5s	128 MB	Judgeable
"Shortest" Pair of PathsFind two vertex-disjoint (except endpoints) and edge-disjoint directed paths from node 0 to node N-1 minimizing total cost, or report impossibility.	Hard8	GraphShortest path+1	No attempts yet	1s	128 MB	Judgeable
Lord of the RingGiven all pairwise distances between bushes on a line, reconstruct the actual bush positions (the classic turnpike/beltway problem) and output the product of adjacent gaps, or report no solution.	Hard8	BacktrackingCombinatorics+1	No attempts yet	1s	128 MB	Judgeable
Beer LandGiven n towns, design a minimal 2-edge-connected road network built from straight segments and compute the maximum possible number of pairwise intersection points among roads.	Hard8	CombinatoricsGeometry+1	No attempts yet	1s	128 MB	Judgeable
Art GalleryCompute the area of the kernel of a simple polygon, the region from which every boundary point is visible, using half-plane intersection.	Hard8	GeometryDivide and conquer+1	No attempts yet	1s	128 MB	Judgeable
BeehivesGiven a graph, find the smallest set of at least two vertices such that the induced subgraph is 2-edge-connected (no bridge disconnects the hive trees).	Hard8	GraphUnion-find+1	No attempts yet	2s	128 MB	Judgeable
ACGUGiven an RLE-encoded RNA-like string, find the maximum number of non-crossing A-U and C-G pairs with at most K C-G pairs, exploiting the special RLE size constraints.	Hard8	Dynamic programmingString+1	No attempts yet	2s	128 MB	Judgeable
Old School DaysGiven N points, compute for each 4-point subset its maximal quadrilateral area (twice), sum all these values modulo 1000003, since the game total is independent of play order.	Hard8	MathCombinatorics+1	No attempts yet	10s	128 MB	Judgeable
Sliding Block PuzzleFind the minimum number of moves to slide a 2x2 king piece and 1x1 pawns through two open cells until the king reaches the frame's top-left corner.	Hard8	BFSGraph+1	No attempts yet	5s	128 MB	Judgeable
Company OrganizationGiven a priority-ordered list of subset/equality/inequality/disjoint/intersect constraints between sets assigned to groups, find the longest satisfiable prefix.	Hard8	Union-findGraph+1	No attempts yet	5s	128 MB	Judgeable
Alphabet SoupCount distinct necklaces (colorings up to rotation by the given rotational symmetry group of the fixed angular positions) with S colors and P beads, using Burnside's lemma modulo a prime.	Hard8	CombinatoricsMath+1	No attempts yet	10s	128 MB	Judgeable
Coin CollectingChoose one envelope from each pair over r rounds so that no non-empty subset of chosen envelopes forms a country-parity cycle (linear independence over GF(2)), maximizing 2 times the number of chosen envelopes.	Hard8	Union-findGreedy+1	No attempts yet	2s	128 MB	Judgeable
Cyber Donut Crime InvestigationFor each query point find the database point minimizing the L1 distance, over many test cases with up to 100000 points and 50000 queries.	Hard8	Divide and conquerBinary search+2	No attempts yet	5s	128 MB	Judgeable
Perfect Square RepublicFind, for each n, the largest perfect square expressible as a product of distinct integers up to n, output mod 1e9+7 for many queries up to n=10^7.	Hard8	Number theoryMath+2	No attempts yet	5s	128 MB	Judgeable
Palindromic DNADecide, given a cyclic DNA alphabet and palindrome constraints on many index subsets with a no-adjacent-change rule, whether a valid ±1/0 edit assignment exists.	Hard8	Union-findGraph+2	No attempts yet	3s	128 MB	Judgeable
Jumping MonkeyGiven a graph with up to 21 nodes representing trees, find the shortest lexicographically smallest shooting sequence that guarantees catching a monkey moving along edges each turn, or report it is impossible.	Hard8	BFSGraph+1	No attempts yet	1s	128 MB	Judgeable
Light Bulb GameCount the ways to pick m distinct switch-combinations over n bulbs (unordered as a set of turns) whose XOR sum turns on exactly the first v bulbs, modulo 10567201.	Hard8	CombinatoricsMath+1	No attempts yet	1s	128 MB	Judgeable