Problems

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Total results29,429 problems

Prevtree
Hard8
Tree, Recursion+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Tower of Hanoi
Hard8
Greedy, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Reducing Tree Height
Hard8
Tree, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Safe Cracking
Hard8
Dynamic programming, Divide and conquer+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Rectangles and Shape
Hard8
Geometry, Intervals+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Race
Hard8
Divide and conquer, Sorting+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Grid Separator
Hard8
Graph, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Building Profit Plan
Hard8
Dynamic programming, Sorting+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Union Area of Right Isosceles Triangles
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Here-There
Hard8
BFS, Recursion+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Number of Expression Values
Hard8
Dynamic programming, String+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Magic Orbs
Hard8
Combinatorics, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Round Trip
Hard8
Shortest path, Graph+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Wedding Procession
Hard8
Dynamic programming, Greedy+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Ganggangsullae Circle
Hard8
Graph, Greedy+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Graph Hash
Hard8
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Obstacle Course Design
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Microbiology Lab
Hard8
Greedy, Segment tree+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Cutting the Stone Slab
Hard8
Dynamic programming, Recursion+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Binary Sequence Rotation
Hard8
String matching, Sorting+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Mirror Restoration
Hard8
Simulation, Backtracking+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Finding a Momentum Sequence
Hard8
String, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Compare Exchange
Hard8
Graph, Union-find+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Square-Substring-Free Number
Hard8
Dynamic programming, String matching+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Drive
Hard8
Shortest path, Graph+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Teleport Route
Hard8
Math, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Garden
Hard8
Binary search, Geometry+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Divisor Subsequence Series
Hard8
Backtracking, Greedy+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Beyond the Walls
Hard8
Graph, BFS+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Number Board Construction
Hard8
Binary search, Graph+1
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
I'm a Frayed Knot
Hard8
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Performing at the Center of the World
Hard8
Geometry, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Cycle with Two Leaves
Hard8
Graph, Combinatorics+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Drive Tour
Hard8
Dynamic programming, Graph+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Visible Squares
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Covering Holes on a Bulletin Board
Hard8
Binary search, Geometry+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Pirate of Busan
Hard8
BFS, Graph+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Lego
Hard8
Combinatorics, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
World-Famous Oil Magnate
Hard8
Segment tree, Binary search+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Total Length of Grid Segments in a Polygon
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Signal Failure
Hard8
Binary search, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Rank Sorting
Hard8
Greedy, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Connecting Points
Hard8
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Student Groups
Hard8
Dynamic programming, Graph+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Cost
Hard8
Union-find, Minimum spanning tree+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hospitals
Hard8
Tree, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Gray Code
Hard8
Combinatorics, Backtracking+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tug of War
Hard8
Binary search, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Emergency Center
Hard8
Graph, Tree+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cross-Polygon Road
Hard8
Shortest path, Geometry+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Easy Group Matching
Hard8
Dynamic programming, Prefix sum+1
No attempts yet
Time limit
30s
Memory limit
1536 MB
Judgeable
Sticks
Hard8
Graph, DFS+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Card Arrangement
Hard8
Topological sort, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Jumping Ladder
Hard8
Binary search, Geometry+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cutting Grid Paper
Hard8
Geometry, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Points
Hard8
Math, Number theory+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Two-Pan Balance Inference
Hard8
Math, Geometry+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bulb Number
Hard8
Bit manipulation, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Last Non-Zero Factorial Digit 2
Hard8
Math, Number theory+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bishop Placement 2
Hard8
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tree Partition
Hard8
Dynamic programming, Tree+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Multiple With the Fewest Digit Types
Hard8
BFS, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Library Carpet
Hard8
Sliding window, Geometry+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Express Bus Routes
Hard8
Greedy, Graph+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Farmland Rearrangement
Hard8
Geometry, Union-find+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Simple Rectangles
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Largest Region in a Rectilinear Polygon
Hard8
Geometry, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Robot
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bus Routes
Hard8
Tree, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Parking Lot
Hard8
BFS, Graph+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Counting Intersections
Hard8
Graph, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fitting a Block
Hard8
Simulation, Geometry+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Building a Fence
Hard8
Geometry, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cargo Truck Collection Routes
Hard8
Tree, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Optimal Reclamation Dam
Hard8
Geometry, Brute force+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Polygon Expansion
Hard8
Geometry, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Triangular Puzzle
Hard8
Backtracking, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Golden Ceiling
Hard8
Geometry, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Kyuhyun and Seunghwan's Twin Birthday Cake
Hard8
Geometry, Binary search+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Smallest K
Hard8
Number theory, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Triangle Garden
Hard8
Geometry, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Spatial Concepts Test
Hard8
Simulation, Geometry+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Message Converter
Hard8
String, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Triangular N-Queen
Hard8
Combinatorics, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Model Rocket Height
Hard8
Geometry, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Histology Outline Tracer
Hard8
DFS, Matrix+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Final Group Photo
Hard8
Combinatorics, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Richest Tenant Company
Hard8
Segment tree, Intervals+1
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Number Strength
Hard8
Math, Number theory+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Mars Bacteria Lineup
Hard8
Dynamic programming, Tree+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Stack Truck Driver
Hard8
Dynamic programming, Stack+1
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Bishop Doodle
Hard8
Dynamic programming, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Dynamic Sequence Data Structure
Hard8
Segment tree, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
I Am a Great Superstar K
Hard8
Greedy, Graph+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Monoliteral Polygons
Hard8
Prefix sum, Geometry+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Beautiful Word
Hard8
Greedy, Game theory+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Black Rectangles
Hard8
Prefix sum, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Antarctic Scientists
Hard8
Tree, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Planet Tunnels
Hard8
Minimum spanning tree, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
CHUCK
Hard8
Matrix, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
PrevtreeGiven the display code sequence (leaf-counts of root and left-children) of a strict binary tree, reconstruct the tree and output the lexicographically previous valid display code with the same leaf count, or 0 if none exists.	Hard8	TreeRecursion+2	No attempts yet	2s	128 MB	Judgeable
Tower of HanoiGiven Tower of Hanoi disks split validly across three rods, find the target rod and minimum moves (mod 1,000,000) to gather all disks on one rod.	Hard8	GreedyMath+1	No attempts yet	2s	128 MB	Judgeable
Reducing Tree HeightGiven a weighted rooted tree, find the minimum total edge-weight reduction needed so every root-to-leaf distance is at most H.	Hard8	TreeDynamic programming+1	No attempts yet	2s	128 MB	Judgeable
Safe CrackingGiven N dial values that can be cyclically increased and merged when adjacent and equal, find the minimum total seconds to make all dials equal, considering rotation direction and wraparound.	Hard8	Dynamic programmingDivide and conquer+1	No attempts yet	2s	128 MB	Judgeable
Rectangles and ShapeGiven a rectilinear polygon and a set of non-overlapping axis-aligned rectangles, select rectangles that exactly tile the polygon's interior without exceeding its boundary.	Hard8	GeometryIntervals+1	No attempts yet	2s	128 MB	Judgeable
RaceGiven starting positions and speeds of N spaceships, count all future overtakes and list the first 10000 in chronological (and positional) order.	Hard8	Divide and conquerSorting+2	No attempts yet	2s	128 MB	Judgeable
Grid SeparatorGiven a grid graph with an initial minimal white/gray/black separator path, find the minimum size separator reachable by specific add/remove transformations.	Hard8	GraphDynamic programming+1	No attempts yet	2s	128 MB	Judgeable
Building Profit PlanGiven points with profits, select a subset maximizing total profit such that every chosen point sees other chosen points only in diagonal quadrant pairs (1,3) or (2,4) relative to itself.	Hard8	Dynamic programmingSorting+1	No attempts yet	2s	128 MB	Judgeable
Union Area of Right Isosceles TrianglesCompute the total area covered by the union of up to 2000 axis-aligned right isosceles triangles with integer coordinates.	Hard8	GeometrySorting+1	No attempts yet	2s	128 MB	Judgeable
Here-ThereGiven a Sierpinski-carpet-like fractal board built by recursively removing center squares, compute the shortest grid path length between two given cells avoiding removed regions.	Hard8	BFSRecursion+2	No attempts yet	2s	128 MB	Judgeable
Number of Expression ValuesCount the distinct values an unspaced digit/operator string can yield when each subexpression is parsed as prefix, infix, or postfix.	Hard8	Dynamic programmingString+2	No attempts yet	2s	128 MB	Judgeable
Magic OrbsConstruct a permutation of rooms 1..N starting at a given M so that consecutive absolute differences use each value 1..N-1 exactly once, visiting every room once.	Hard8	CombinatoricsMath+1	No attempts yet	2s	128 MB	Judgeable
Round TripFind two edge-disjoint paths between node 1 and node N in a weighted graph minimizing total combined length, essentially a min-cost flow problem.	Hard8	Shortest pathGraph+1	No attempts yet	2s	128 MB	Judgeable
Wedding ProcessionArrange all guests in a line minimizing the sum of adjacent height differences while keeping the given lion subsequence order fixed.	Hard8	Dynamic programmingGreedy+1	No attempts yet	2s	128 MB	Judgeable
Ganggangsullae CircleArrange n students in a circle using a dense friendship graph to minimize the number of students whose left neighbor is not a friend, exploiting the very high edge count guarantee.	Hard8	GraphGreedy+1	No attempts yet	1s	512 MB	Judgeable
Graph HashGiven a weighted graph with up to 30 vertices, compute the LCM over all simple paths from vertex 1 to 2 of the GCD of edge weights on each path, with results up to 1000 digits.	Hard8	GraphDFS+2	No attempts yet	2s	128 MB	Judgeable
Obstacle Course DesignCount the number of ways to arrange m distinct-height obstacles into a nested valid course whose ground-to-ground climbing difficulty equals exactly k.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	2s	128 MB	Judgeable
Microbiology LabChoose the minimum number of distinct integer temperature points so every microbe's interval contains at least C[i] chosen points.	Hard8	GreedySegment tree+2	No attempts yet	2s	128 MB	Judgeable
Cutting the Stone SlabCount the number of ways to repeatedly cut an N x N stone slab with alternating horizontal/vertical straight cuts so every final piece has no impurity and exactly one crystal.	Hard8	Dynamic programmingRecursion+2	No attempts yet	2s	128 MB	Judgeable
Binary Sequence RotationGiven the last column of a sorted matrix of all circular rotations of an unknown binary string, reconstruct the lexicographically smallest rotation (first row) or report impossibility.	Hard8	String matchingSorting+2	No attempts yet	2s	128 MB	Judgeable
Mirror RestorationReconstruct an N by M grid of empty cells and '/' mirrors so that shooting rays from all 2N+2M boundary holes matches a given exit-hole permutation.	Hard8	SimulationBacktracking+1	No attempts yet	2s	128 MB	Judgeable
Finding a Momentum SequenceGiven a digit string, decide if it can be split into an arithmetic progression followed by a term equal to the last progression term times some integer f, and output the minimal possible f.	Hard8	StringMath+2	No attempts yet	1s	1024 MB	Judgeable
Compare ExchangeGiven a sequence of compare-exchange calls, find the minimum number of extra calls to append so index 1 always ends with the minimum and the program stays minimal after removing any single call.	Hard8	GraphUnion-find+1	No attempts yet	2s	128 MB	Judgeable
Square-Substring-Free NumberGiven N up to 10^18, find the smallest number at least N whose decimal representation contains no perfect square as a substring.	Hard8	Dynamic programmingString matching+1	No attempts yet	1s	1024 MB	Judgeable
DriveFind a path from S to T in a weighted undirected graph minimizing extra cost incurred whenever an edge's weight falls outside the running min-max range of used edges.	Hard8	Shortest pathGraph+2	No attempts yet	2s	128 MB	Judgeable
Teleport RouteGiven 2^n planets and one usable teleport for each distance from 1 to 2^n-1, find an ordering starting at k that visits the maximum number of distinct planets and print the signed teleport sequence.	Hard8	MathGreedy+2	No attempts yet	1s	128 MB	Judgeable
GardenGiven n points, find the axis-aligned square of minimum side length that covers at least half the points, allowing real coordinates and boundary inclusion.	Hard8	Binary searchGeometry+1	No attempts yet	2s	128 MB	Judgeable
Divisor Subsequence SeriesGiven N, repeatedly delete digits forming a proper divisor subsequence to build the longest possible chain, breaking ties lexicographically smallest.	Hard8	BacktrackingGreedy+2	No attempts yet	2s	128 MB	Judgeable
Beyond the WallsGiven a planar subdivision formed by non-crossing walls, build the dual graph of regions incident to member villages and find the region minimizing total shortest-path crossings to reach all club members.	Hard8	GraphBFS+1	No attempts yet	2s	128 MB	Judgeable
Number Board ConstructionFill an N by N nonnegative integer grid matching given row and column sums while minimizing the maximum cell value, essentially a binary-search plus bipartite flow feasibility problem.	Hard8	Binary searchGraph+1	No attempts yet	5s	128 MB	Judgeable
I'm a Frayed KnotGiven sequences of colored thread endpoints, count the orderings of adjacent ties that merge all threads into a single loop without prematurely closing a smaller cycle.	Hard8	CombinatoricsDynamic programming+1	No attempts yet	1s	128 MB	Judgeable
Performing at the Center of the WorldGiven up to 100 points on a plane, compute the center and radius of the minimum enclosing circle covering all of them.	Hard8	GeometryMath+1	No attempts yet	2s	128 MB	Judgeable
Cycle with Two LeavesCount subgraphs formed by a 4-cycle plus two pendant edges attached to the same cycle vertex, modulo 1e9+7.	Hard8	GraphCombinatorics+1	No attempts yet	4s	1024 MB	Judgeable
Drive TourFind two vertex-disjoint (except endpoints) monotonic increasing and decreasing paths between city 1 and city N that together visit the maximum number of distinct cities, and output the combined route.	Hard8	Dynamic programmingGraph+1	No attempts yet	2s	128 MB	Judgeable
Visible SquaresGiven up to 1000 non-overlapping axis-aligned integer squares, count how many are visible from the origin by angular occlusion reasoning.	Hard8	GeometrySorting+1	No attempts yet	2s	128 MB	Judgeable
Covering Holes on a Bulletin BoardGiven points on a plane, find the minimum side length of two identical axis-aligned squares that together cover all points, and output their positions.	Hard8	Binary searchGeometry+1	No attempts yet	2s	128 MB	Judgeable
Pirate of BusanGiven a grid with islands, decide if a player can reach a treasure while an adversarial pirate moves each turn, avoiding capture via same-row/column line of sight rules, for grids up to 700x700.	Hard8	BFSGraph+1	No attempts yet	1s	128 MB	Judgeable
LegoCount 3D Lego constructions on a 6x6 base made of 2x2 colored blocks consistent with two given silhouette views from perpendicular directions.	Hard8	CombinatoricsSimulation+2	No attempts yet	1s	128 MB	Judgeable
World-Famous Oil MagnateMaintain tree heights under two operations, fertilize the C smallest trees whose height is at least H by raising each by 1, and answer range count queries, efficiently.	Hard8	Segment treeBinary search+1	No attempts yet	1s	128 MB	Judgeable
Total Length of Grid Segments in a PolygonGiven a simple polygon with integer vertices, compute the total length of grid line segments strictly inside the polygon.	Hard8	GeometrySorting+1	No attempts yet	1s	128 MB	Judgeable
Signal FailureGiven trains scattered on a two-rail loop with reversible directions, compute the minimum time to redistribute them into an evenly spaced periodic pattern.	Hard8	Binary searchGreedy+2	No attempts yet	1s	128 MB	Judgeable
Rank SortingGiven n distinct scores, output a minimum-cost sequence of single-element move operations (cost i+j each) that sorts them in descending order.	Hard8	GreedyArray+1	No attempts yet	1s	128 MB	Judgeable
Connecting PointsCount simple Hamiltonian polygons using all 3xN grid points with king-move adjacency, for N up to 1e9, mod 1e9.	Hard8	CombinatoricsDynamic programming+1	No attempts yet	1s	128 MB	Judgeable
Student GroupsPartition an ordered list of students into contiguous groups minimizing mismatches between grouping and a given friendship graph, using DP over prefix structure with an efficient cost computation.	Hard8	Dynamic programmingGraph+1	No attempts yet	1s	256 MB	Judgeable
CostGiven a weighted graph, compute the sum over all vertex pairs of the total weight removed when repeatedly deleting the smallest edge until the pair is disconnected, modulo 1e9.	Hard8	Union-findMinimum spanning tree+1	No attempts yet	1s	128 MB	Judgeable
HospitalsGiven a tree with populations and hospital villages, allocate a limited road-improvement budget with a per-road floor to minimize total or maximum travel time to the nearest hospital.	Hard8	TreeGreedy+1	No attempts yet	1s	128 MB	Judgeable
Gray CodeConstruct a cyclic Gray code of length M bits that includes one or two specified adjacent pairs, or report impossibility.	Hard8	CombinatoricsBacktracking+1	No attempts yet	1s	128 MB	Judgeable
Tug of WarSplit two weighted sequences each into three ordered nonempty contiguous parts so paired-part weight differences stay under 50 and the maximum difference is minimized.	Hard8	Binary searchPrefix sum+1	No attempts yet	1s	128 MB	Judgeable
Emergency CenterGiven a graph that is a cycle with trees hanging off it, place two facilities at stations to minimize the maximum shortest-path distance from any station to its nearest facility.	Hard8	GraphTree+1	No attempts yet	1s	128 MB	Judgeable
Cross-Polygon RoadGiven a convex polygon with a cycle road, choose one chord to add so that the resulting maximum shortest-path distance between any two vertices is minimized.	Hard8	Shortest pathGeometry+1	No attempts yet	1s	128 MB	Judgeable
Easy Group MatchingGiven a text sequence and two patterns, count group-matching positions for each pattern, then find the smallest integer n that maximizes group matches for the concatenated pattern P1·n·P2 and report that count.	Hard8	Dynamic programmingPrefix sum+1	No attempts yet	30s	1536 MB	Judgeable
SticksGiven N triples of sticks, decide if removing at most one stick per triple can make all remaining sticks pairwise non-crossing, and output a valid removal set.	Hard8	GraphDFS+1	No attempts yet	1s	128 MB	Judgeable
Card ArrangementGiven N cards and P pairwise greater-than constraints on k chosen positions forming a base-N number, compute the modular difference between the maximum and minimum valid values.	Hard8	Topological sortGreedy+1	No attempts yet	1s	128 MB	Judgeable
Jumping LadderGiven bouncing rods on N floors moving at constant speeds, find the minimum time to climb from the bottom floor to the top floor by jumping only between overlapping rods within K floors.	Hard8	Binary searchGeometry+2	No attempts yet	1s	128 MB	Judgeable
Cutting Grid PaperGiven a rectangular sheet and a cut-out polygon on grid lines, compute how many paper pieces remain and the largest perimeter among them, accounting for holes.	Hard8	GeometrySimulation+1	No attempts yet	1s	128 MB	Judgeable
PointsDetermine reachability of points under a closure of shift, halving-when-even, and transitivity rules starting from one point, essentially characterizing (x,y) pairs by an invariant like x-y modulo constraints and gcd-related structure.	Hard8	MathNumber theory+1	No attempts yet	1s	128 MB	Judgeable
Two-Pan Balance InferenceGiven up to 10 weighing inequalities among counts of A, B, and 1-gram weights, decide for each of five queries whether the left or right side must be heavier for all valid A,B values, or whether it is undetermined.	Hard8	MathGeometry+1	No attempts yet	1s	128 MB	Judgeable
Bulb NumberGiven wires connecting switches to bulbs where crossing wires turn bulbs off when pressed together, find the K-th smallest binary number achievable by some subset of pressed switches.	Hard8	Bit manipulationGreedy+2	No attempts yet	1s	128 MB	Judgeable
Last Non-Zero Factorial Digit 2Compute the last nonzero digit of N! for an N with up to 100 digits, requiring a modular recursive formula rather than direct computation.	Hard8	MathNumber theory+1	No attempts yet	1s	128 MB	Judgeable
Bishop Placement 2Given an N by N chessboard with obstacle cells that block diagonal movement, find the maximum number of mutually non-attacking bishops that can be placed.	Hard8	GraphBFS+2	No attempts yet	1s	128 MB	Judgeable
Tree PartitionChoose exactly K vertices in a weighted tree to minimize the total weight of edges whose endpoints share the same chosen/unchosen status, and output the chosen vertex set.	Hard8	Dynamic programmingTree+1	No attempts yet	1s	128 MB	Judgeable
Multiple With the Fewest Digit TypesGiven N up to 30000, find the smallest positive multiple of N that uses the fewest distinct decimal digits.	Hard8	BFSMath+2	No attempts yet	1s	128 MB	Judgeable
Library CarpetGiven non-overlapping axis-aligned stains in a library, find the best position for a fixed-size square carpet that fully contains the maximum number of stain rectangles.	Hard8	Sliding windowGeometry+1	No attempts yet	1s	128 MB	Judgeable
Express Bus RoutesAssign leftover cities as intermediate stops to N given start-end bus routes across three countries under strict country-adjacency constraints, then output each completed route.	Hard8	GreedyGraph+1	No attempts yet	1s	128 MB	Judgeable
Farmland RearrangementGiven a rectangle divided by straight embankment segments that only meet at endpoints, compute the area of the largest resulting field.	Hard8	GeometryUnion-find+1	No attempts yet	1s	128 MB	Judgeable
Simple RectanglesGiven the vertex sequence of a rectilinear polygon path with crossing segments, count how many resulting regions are empty rectangles.	Hard8	GeometrySorting+1	No attempts yet	1s	128 MB	Judgeable
Largest Region in a Rectilinear PolygonGiven a self-intersecting rectilinear polygon, find the maximum area among the simple polygonal regions its edges partition the plane into.	Hard8	GeometrySimulation+1	No attempts yet	1s	128 MB	Judgeable
RobotGiven axis-aligned L-shaped obstacles on a plane, find the minimum number of turns in an orthogonal path from a start point to a destination avoiding the obstacles.	Hard8	GraphShortest path+1	No attempts yet	1s	128 MB	Judgeable
Bus RoutesGiven a tree with degree at most 10, partition all edges into leaf-to-leaf simple paths covering every vertex while minimizing the maximum path length, or report impossibility.	Hard8	TreeGreedy+2	No attempts yet	1s	128 MB	Judgeable
Parking LotFind and output a minimum-operation sequence of car moves in the classic Rush Hour parking puzzle to free car 1 from an N by N grid.	Hard8	BFSGraph+1	No attempts yet	1s	128 MB	Judgeable
Counting IntersectionsGiven pairs of boundary points on a rectangle, determine the minimum total crossings needed to connect each pair with a curve inside the rectangle, and the largest crossing count on one curve among optimal drawings.	Hard8	GraphCombinatorics+1	No attempts yet	1s	128 MB	Judgeable
Fitting a BlockGiven a board of C-shaped blocks and a T-shaped block that can be rotated but not flipped, find every C-shaped block whose notch can be exactly filled by the T-block to form a rectangle without overlapping other blocks or exiting the board.	Hard8	SimulationGeometry+1	No attempts yet	1s	128 MB	Judgeable
Building a FenceFind the minimum-area rectangle with integer-coordinate vertices that encloses all given points, allowing arbitrary rotation, with a specific tie-breaking output rule.	Hard8	GeometryMath+1	No attempts yet	1s	128 MB	Judgeable
Cargo Truck Collection RoutesGiven a tree rooted at the depot with cargo weights at nodes, plan truck trips of capacity 10 minimizing total travel distance, splitting cargo as needed, and output the routes.	Hard8	TreeGreedy+1	No attempts yet	1s	128 MB	Judgeable
Optimal Reclamation DamGiven a rectilinear simple polygon coastline, find a straight horizontal or vertical interior-free chord splitting off a region that maximizes enclosed area divided by chord length.	Hard8	GeometryBrute force+1	No attempts yet	1s	128 MB	Judgeable
Polygon ExpansionGiven a rectilinear simple polygon, compute the outward offset polygon by distance d, merging filled concave regions and outputting vertices in a fixed starting order.	Hard8	GeometrySimulation+1	No attempts yet	1s	128 MB	Judgeable
Triangular PuzzleReconstruct a triangular 0/1 matrix from run-length block sequences given for every row and column, or report impossibility.	Hard8	BacktrackingCombinatorics+1	No attempts yet	1s	128 MB	Judgeable
Golden CeilingGiven a box and a tilted plane forming a ceiling, compute the total gold-leaf area combining the plane's surface inside the box and the flat ceiling area where the plane exceeds the ceiling height, rounded up.	Hard8	GeometryMath+1	No attempts yet	1s	128 MB	Judgeable
Kyuhyun and Seunghwan's Twin Birthday CakeGiven a triangle's vertices, compute a line (in normalized Ax+By=C form) that splits the triangle into two regions of equal area and equal perimeter simultaneously.	Hard8	GeometryBinary search+1	No attempts yet	1s	128 MB	Judgeable
Smallest KFind, for each given R, the smallest exponent k such that the last R decimal digits of 2^k are all 1s or 2s, using digit-by-digit lifting with modular arithmetic.	Hard8	Number theoryMath+1	No attempts yet	1s	128 MB	Judgeable
Triangle GardenGiven a triangle's vertices, compute the two foci and string length of the Steiner inellipse tangent at each side's midpoint.	Hard8	GeometryMath	No attempts yet	1s	128 MB	Judgeable
Spatial Concepts TestGiven a labeled cube net with oriented pictures on each face, determine which of five given corner views (top, right, left faces with orientations) can actually result from folding and rotating the cube.	Hard8	SimulationGeometry+1	No attempts yet	1s	128 MB	Judgeable
Message ConverterParse a MULTI markup string with tags for newline, justification, and spacing, then render it into a fixed-size character grid while detecting conflict, size, and syntax errors.	Hard8	StringSimulation+1	No attempts yet	1s	128 MB	Judgeable
Triangular N-QueenFor each N, output the known-optimal count floor((2N+1)/3) of mutually non-attacking queens on a triangular board and a valid placement achieving it.	Hard8	CombinatoricsMath+1	No attempts yet	1s	128 MB	Judgeable
Model Rocket HeightCompute a model rocket's height above ground from three collinear observers' elevation angles, baseline spacing, and instrument height, using 3D geometry.	Hard8	GeometryMath+1	No attempts yet	1s	128 MB	Judgeable
Histology Outline TracerTrace clockwise boundary contours of stained connected regions in a bitmap, ignoring small regions, using an 8-direction outline code.	Hard8	DFSMatrix+1	No attempts yet	1s	128 MB	Judgeable
Final Group PhotoCount the ways to fill a decreasing-width staircase of rows (back rows longer) with distinct heights so rows decrease left to right and columns decrease from back to front, essentially counting standard Young tableaux for a skew shape.	Hard8	CombinatoricsMath+1	No attempts yet	1s	128 MB	Judgeable
Richest Tenant CompanyProcess chronological move-ins and range-max inspections on offices where each company's wealth grows linearly with time, requiring a segment tree over linear functions evaluated at the query day.	Hard8	Segment treeIntervals+1	No attempts yet	5s	128 MB	Judgeable
Number StrengthGiven a huge range [A,B] with B up to 1e17, sum the lengths of chains formed by repeatedly replacing N with the smallest integer not dividing it until reaching 2.	Hard8	MathNumber theory+1	No attempts yet	1s	128 MB	Judgeable
Mars Bacteria LineupGiven a repulsion matrix, choose left/right swap at every node of a complete binary tree to minimize the total sum of adjacent-pair distances in the resulting leaf permutation.	Hard8	Dynamic programmingTree+2	No attempts yet	1s	128 MB	Judgeable
Stack Truck DriverCount length-bounded walks from city 1 to city N in a graph where edges push or pop letters on a stack, with pops requiring a matching top element.	Hard8	Dynamic programmingStack+1	No attempts yet	3s	128 MB	Judgeable
Bishop DoodleSimulate two bishops on a 2N by 2N board moving K times to maximize the sum of newly-seen cells not previously visible to either bishop.	Hard8	Dynamic programmingSimulation+2	No attempts yet	1s	128 MB	Judgeable
Dynamic Sequence Data StructureDesign a data structure supporting range assignment, range arithmetic-progression addition, mid-sequence insertion, and range-sum queries efficiently.	Hard8	Segment treeArray+1	No attempts yet	1s	128 MB	Judgeable
I Am a Great Superstar KGiven N contestants' scores in M genres (each genre's scores listed sorted), pick K contestant-genre assignments (one genre per chosen contestant) maximizing total score, requiring a min-cost/max-flow or matroid intersection style greedy insight.	Hard8	GreedyGraph+1	No attempts yet	1s	128 MB	Judgeable
Monoliteral PolygonsCount integer translations of a given rectilinear polygon so it stays inside a lettered grid and covers cells of only one letter.	Hard8	Prefix sumGeometry+1	No attempts yet	2s	128 MB	Judgeable
Beautiful WordSimulate a turn-based letter-picking game where one player greedily takes the rightmost slip while the other picks optimally to form the lexicographically smallest possible word, then compare outcomes.	Hard8	GreedyGame theory+1	No attempts yet	1s	128 MB	Judgeable
Black RectanglesCount unordered pairs of disjoint all-black axis-aligned rectangles (each containing at least two cells) in an up to 1000x1000 grid, modulo 10007.	Hard8	Prefix sumCombinatorics+1	No attempts yet	1s	128 MB	Judgeable
Antarctic ScientistsCompute the exact character count needed to render an ASCII family tree with fixed box drawing and branching link rules given a forest with up to two children per node.	Hard8	TreeRecursion+2	No attempts yet	1s	128 MB	Judgeable
Planet TunnelsGiven N 3D points with edge cost equal to the minimum coordinate-axis distance between two points, find the minimum spanning tree cost connecting all of them efficiently.	Hard8	Minimum spanning treeSorting+1	No attempts yet	1s	128 MB	Judgeable
CHUCKGiven a matrix with row/column rotation and one-time row/column sign flip operations, compute the maximum achievable total sum.	Hard8	MatrixGreedy+1	No attempts yet	1s	128 MB	Judgeable