Problems

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Total results29,137 problems

Ridges and Valleys
Medium7
Graph, DFS+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
The Flood
Medium7
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Megalopolis
Medium7
Tree, DFS+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Railway Network
Medium7
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Weights
Medium7
Greedy, Sorting+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Postering
Medium7
Stack, Greedy
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Robinson
Medium7
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Blockade
Medium7
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
BBB
Medium7
Greedy, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Trains
Medium7
Hash map, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Mafia
Medium7
Graph, Greedy+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
The Great Escape
Medium7
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Triangles
Medium7
Sorting
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Multiset Permutation Rank
Medium7
Combinatorics, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Station
Medium7
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Algorithm Speedup
Medium7
Recursion, Hash map+2
No attempts yet
Time limit
8s
Memory limit
128 MB
Judgeable
Fire Brigade
Medium7
Geometry, Sorting+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Ticket Inspector
Medium7
Dynamic programming, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hexer
Medium7
Shortest path, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Guilds
Medium7
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Railway Siding
Medium7
Stack, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Blocks
Medium7
Greedy, Two pointers+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Monotonicity
Medium7
Dynamic programming, Binary search+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
The Minima Game
Medium7
Greedy, Sorting+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Bridges
Medium7
Graph, Binary search+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Conspiracy
Medium7
Graph, Combinatorics+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Lollipop
Medium7
Prefix sum, Two pointers+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Shift
Medium7
Array, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Strongbox
Medium7
Number theory, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Letter Frequency Difference
Medium7
Dynamic programming, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tree Rotations
Medium7
Divide and conquer, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Party
Medium7
Greedy, Graph+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Sticks
Medium7
Sorting, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Team Programming Contest
Medium7
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Rearranging Letters
Medium7
Greedy, Sorting+1
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Tour de Byteotia
Medium7
Graph, DFS+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Cloakroom
Medium7
Dynamic programming, Sorting+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Walk
Medium7
BFS, Graph+2
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Tales of Seafaring
Medium7
Graph, BFS+1
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Around the World
Medium7
Graph, Shortest path+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Banjo
Medium7
Array, Sorting+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Road Renovation
Medium7
Graph, Minimum spanning tree+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Winter Snow Plowing
Medium7
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Alien Invasion
Medium7
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Crop Circles
Medium7
Geometry, Sorting
No attempts yet
Time limit
8s
Memory limit
256 MB
Judgeable
Orchard
Medium7
Divide and conquer, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Climbing
Medium7
Dynamic programming, Greedy
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Double Factorial
Medium7
Math, Binary search+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Squared Words
Medium7
Dynamic programming, String
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Evacuation
Medium7
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Goat
Medium7
Probability, Geometry+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bytie's Display
Medium7
Greedy, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Byton Tree
Medium7
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Planning the Roadworks
Medium7
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Riddle
Medium7
Graph, Greedy+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Variable Subsequences
Medium7
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sweets
Medium7
Brute force, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
(K, N)-Knight
Medium7
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Dice
Medium7
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pawn
Medium7
Union-find, Intervals+2
No attempts yet
Time limit
1s
Memory limit
192 MB
Judgeable
Byteantean Towns
Medium7
Geometry, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Circular Game
Medium7
Game theory, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Type Two de Bruijn Sequences
Medium7
Greedy, String+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Studies
Medium7
Graph, Shortest path+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Mosaicism
Medium7
Combinatorics, Bit manipulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Potato
Medium7
Geometry, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sport Clubs
Medium7
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Buses
Medium7
Sorting, Binary search+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Barricades
Medium7
Tree, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Straight Lines 2
Medium7
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sunsets
Medium7
Dynamic programming, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Farmer's Field
Medium7
Sliding window, Stack+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Words
Medium7
Dynamic programming, String
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ant
Medium7
Matrix, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Professor Laugh's Numbers
Medium7
Number theory, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Strong-box
Medium7
Math, Matrix+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Rooks
Medium7
Combinatorics, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bus Lines
Medium7
Graph, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Space Base Construction
Medium7
Geometry, Binary search+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ball Boxes
Medium7
Greedy, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Roads
Medium7
Graph, DFS+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Billiards
Medium7
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Critical Computers of the Byteland Information Agency
Medium7
Graph, DFS+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Parentheses
Medium7
Segment tree, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Supernumbers in a Permutation
Medium7
Dynamic programming, Binary search+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tomki
Medium7
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Interplanetary Vacation
Medium7
Math, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Chocolate
Medium7
Game theory, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Highway Construction Plan
Medium7
Graph, Minimum spanning tree+1
No attempts yet
Time limit
1s
Memory limit
192 MB
Judgeable
Physical Education
Medium7
Array, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Land Swindle
Medium7
Dynamic programming, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Trams
Medium7
Tree, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Divisor Game
Medium7
Dynamic programming, Game theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Vacation
Medium7
Dynamic programming, Sliding window+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Monopoly
Medium7
Graph, Union-find+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tower
Medium7
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Triangles
Medium7
Sorting, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Two Postmen
Medium7
Tree, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Highway Modernization
Medium7
Shortest path, Binary search+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fiber Optic Network
Medium7
Segment tree, Tree+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Ridges and ValleysCount connected components of equal height in an n by n grid whose every boundary neighbor is strictly lower (ridge) or strictly higher (valley).	Medium7	GraphDFS+2	No attempts yet	3s	128 MB	Judgeable
The FloodGiven a grid of heights where city squares must be drained, find the minimum number of pumps so that water flows downhill from each city square to a pump.	Medium7	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
MegalopolisCount, for each query at a given moment, the number of still-country roads on the path from village 1 to a target village as edges are removed one by one.	Medium7	TreeDFS+1	No attempts yet	1s	128 MB	Judgeable
Railway NetworkGiven a connected edge-weighted graph and at most 8 terminals, find the minimum cost edge set that keeps all terminals mutually connected.	Medium7	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
WeightsGiven container capacities and weights whose masses form a divisibility chain, maximize how many weights fit.	Medium7	GreedySorting+2	No attempts yet	3s	128 MB	Judgeable
PosteringGiven adjacent buildings with widths and heights, find the minimum number of non-overlapping rectangles needed to cover the whole skyline shape.	Medium7	StackGreedy	No attempts yet	1s	128 MB	Judgeable
RobinsonGiven an n by n grid with a boat shape, water, and obstacles, find the minimum number of unit translations in four directions to slide the boat completely off the map.	Medium7	BFSGraph+2	No attempts yet	1s	128 MB	Judgeable
BlockadeFor each town, count planned visits ruined if it alone is removed, i.e. those crossing it plus visits to and from it.	Medium7	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
BBBFind the minimum cost to fix a + and - statement so the balance starts at p, never goes negative, and ends at q, using character flips and rotations.	Medium7	GreedyPrefix sum+1	No attempts yet	1s	128 MB	Judgeable
TrainsAfter each of m car swaps, track the largest number of trains that ever shared each train's exact colour string.	Medium7	Hash mapString+1	No attempts yet	1s	128 MB	Judgeable
MafiaEach mobster aims at one target; find the minimum and maximum possible number of deaths over all shooting orders.	Medium7	GraphGreedy+1	No attempts yet	2s	128 MB	Judgeable
The Great EscapeCount escape routes on an n by m grid where the driver enters at the bottom-left corner heading north, only goes straight or turns right, and never revisits an intersection.	Medium7	Dynamic programmingCombinatorics+1	No attempts yet	1s	128 MB	Judgeable
TrianglesSum the areas of all triangles formed by n given points, counting 2*area via absolute cross products.	Medium7	Sorting	No attempts yet	3s	128 MB	Judgeable
Multiset Permutation RankGiven one permutation of a multiset, compute its lexicographic rank among all distinct permutations, modulo m.	Medium7	CombinatoricsMath+2	No attempts yet	2s	128 MB	Judgeable
StationPick a tree vertex as the hub so that the average number of hub-to-vertex paths needed to travel between unordered pairs of vertices is minimized.	Medium7	TreeDFS+2	No attempts yet	1s	128 MB	Judgeable
Algorithm SpeedupDecide whether a recursively defined Boolean function F on two sequences returns 1 or 0, where F strips the longest prefix and suffix that drop some value.	Medium7	RecursionHash map+2	No attempts yet	8s	128 MB	Judgeable
Fire BrigadeFor each of p pairs of fire stations, count how many monuments are strictly closer to the first, strictly closer to the second, and equally close under Manhattan distance.	Medium7	GeometrySorting+1	No attempts yet	3s	512 MB	Judgeable
Ticket InspectorChoose k of the n-1 travel segments so that the total number of passengers present on at least one chosen segment is maximized.	Medium7	Dynamic programmingPrefix sum+1	No attempts yet	1s	128 MB	Judgeable
HexerFind the shortest walk from town 1 to town n where each road can be used only after collecting swords for all monster kinds on it.	Medium7	Shortest pathGraph+2	No attempts yet	1s	128 MB	Judgeable
GuildsSplit the towns into two sets so that each set is a dominating set and the sets are disjoint, or decide it is impossible.	Medium7	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
Railway SidingAssign each arriving car to one of two stack-like sidetracks so all cars leave in increasing order.	Medium7	StackGreedy+1	No attempts yet	1s	128 MB	Judgeable
BlocksGiven pile heights, for each k find the longest run of consecutive piles that can be raised to height at least k by moving top blocks between neighbors while staying above k.	Medium7	GreedyTwo pointers+1	No attempts yet	3s	512 MB	Judgeable
MonotonicityFind the longest subsequence of a sequence whose adjacent comparison symbols repeat a given pattern of <, >, = of length k.	Medium7	Dynamic programmingBinary search+2	No attempts yet	3s	512 MB	Judgeable
The Minima GameTwo players alternately take any positive number of cards and score the minimum value in the taken set; find the optimal final score difference for the first player.	Medium7	GreedySorting+1	No attempts yet	3s	512 MB	Judgeable
BridgesFind an Eulerian circuit from island 1 minimizing the maximum directed edge cost, or report that no such circuit exists.	Medium7	GraphBinary search+1	No attempts yet	3s	512 MB	Judgeable
ConspiracyGiven a mutual acquaintance graph on n people, count the ways to split all n people into a nonempty independent set (conspirators) and a nonempty clique (support) that together cover everyone.	Medium7	GraphCombinatorics+2	No attempts yet	3s	128 MB	Judgeable
LollipopFor each query k, find the lexicographically smallest contiguous segment of a T/W string whose weight (T=2, W=1) equals k, or print NIE if none exists.	Medium7	Prefix sumTwo pointers+2	No attempts yet	1s	128 MB	Judgeable
ShiftGiven a permutation of 1 to n, decide whether it can be sorted using only two moves: bring the last element to the front, or bring the third element to the front.	Medium7	ArrayImplementation+2	No attempts yet	1s	128 MB	Judgeable
StrongboxGiven that only the last of k tried dial positions opens a safe, find the maximum possible number of opening positions consistent with the closure rule (x+y) mod n.	Medium7	Number theoryMath+1	No attempts yet	1s	128 MB	Judgeable
Letter Frequency DifferencePick any contiguous fragment of a lowercase word to maximize the gap between its most and least frequent letters.	Medium7	Dynamic programmingPrefix sum+1	No attempts yet	1s	128 MB	Judgeable
Tree RotationsGiven a binary tree with distinct leaf labels, find the minimum number of inversions in the left-to-right leaf sequence reachable by swapping children at branchings.	Medium7	Divide and conquerDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
PartyRun a deterministic greedy procedure where each vertex is added to a clique candidate if it knows everyone on the list, otherwise the smallest non-neighbor is removed, then print the smallest n/3 remaining.	Medium7	GreedyGraph+2	No attempts yet	3s	128 MB	Judgeable
SticksFrom sticks grouped by colour, find three sticks of pairwise different colours that form a non-degenerate triangle and maximise the perimeter.	Medium7	SortingGreedy+1	No attempts yet	1s	128 MB	Judgeable
Team Programming ContestEach member-computer can solve a sequence of problems they are able to solve, each taking r minutes; maximize the number solved within t minutes and minimize total penalty.	Medium7	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
Rearranging LettersGiven two equal-length anagrams, count the minimum adjacent swaps needed to turn the first string into the second.	Medium7	GreedySorting+1	No attempts yet	3s	128 MB	Judgeable
Tour de ByteotiaBlock the fewest roads so no closed trail (no repeated road) passes through any of towns 1 to k.	Medium7	GraphDFS+2	No attempts yet	3s	128 MB	Judgeable
CloakroomFor each query (m, k, s), decide whether some items with a_i <= m and b_i > m+s have values summing to exactly k.	Medium7	Dynamic programmingSorting+2	No attempts yet	2s	128 MB	Judgeable
WalkGiven up to one million missing strings among n-bit names, decide whether two present names are connected through single-bit flips avoiding blocked names.	Medium7	BFSGraph+2	No attempts yet	5s	256 MB	Judgeable
Tales of SeafaringGiven an undirected graph, decide for each of k queries whether a walk of exactly d edges exists from s to t.	Medium7	GraphBFS+1	No attempts yet	5s	128 MB	Judgeable
Around the WorldFind the cheapest closed walk from city 1 whose total eastward longitude differs from its westward longitude.	Medium7	GraphShortest path+1	No attempts yet	1s	128 MB	Judgeable
BanjoPick two separate one-minute intervals to maximize the number of people present for at least one full minute.	Medium7	ArraySorting+2	No attempts yet	5s	128 MB	Judgeable
Road RenovationChoose a cheapest set of directed roads so every city has at least one chosen road entering and one leaving it, or report impossibility.	Medium7	GraphMinimum spanning tree+2	No attempts yet	1s	128 MB	Judgeable
Winter Snow PlowingOn a tree, each edge must be traversed at least d_i times by one continuous walk; find the minimum total traversal count.	Medium7	TreeDFS+2	No attempts yet	1s	128 MB	Judgeable
Alien InvasionFind the maximum total residents the aliens can abduct, given that a warning from an attacked city reaches city k one day later per unit distance.	Medium7	Dynamic programmingGreedy+2	No attempts yet	1s	128 MB	Judgeable
Crop CirclesCount how many pairs of given circles touch at exactly one point.	Medium7	GeometrySorting	No attempts yet	8s	256 MB	Judgeable
OrchardGiven an n by n grid of trees and empty cells, decide whether the whole grid can be split into exactly k axis-aligned rectangles, each containing at least one tree.	Medium7	Divide and conquerDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
ClimbingEach of n pairs of climbers sits on adjacent routes with two positions a and b; maximize the number of adjacent climbers (across neighboring routes) that can share the same height under the rope constraints.	Medium7	Dynamic programmingGreedy	No attempts yet	1s	128 MB	Judgeable
Double FactorialCount the trailing zeros of the product of the first n factorials, where n can reach 10^18.	Medium7	MathBinary search+1	No attempts yet	1s	128 MB	Judgeable
Squared WordsGiven a lowercase string, delete the fewest letters so the remaining letters, in order, form a squared word xx.	Medium7	Dynamic programmingString	No attempts yet	1s	128 MB	Judgeable
EvacuationFind the minimum number of directed edges to remove so that no path of length at most three remains from node 1 to node n.	Medium7	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
The GoatCompute the expected area eaten when a goat is tied for k days to uniformly random stakes of length l, where overlaps depend on disk-pair geometry.	Medium7	ProbabilityGeometry+2	No attempts yet	1s	128 MB	Judgeable
Bytie's DisplayReorder the digits of a seven-segment display and flip at most n segments so the result reads as the lexicographically largest l-digit number.	Medium7	GreedyDynamic programming+1	No attempts yet	1s	128 MB	Judgeable
Byton TreeGiven a tree in recursive notation, where each leaf has a time interval, find the minimum number of cuts (each cut picks every byton in the subtree at one moment) so that all intervals are covered.	Medium7	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
Planning the RoadworksGiven a directed graph, find a lexicographically smallest inclusion-maximal set of edges whose simultaneous removal leaves the reachability relation unchanged.	Medium7	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
RiddleDecide whether one town can be picked from each given group so that every edge of the graph has a chosen endpoint.	Medium7	GraphGreedy+1	No attempts yet	3s	1024 MB	Judgeable
Variable SubsequencesCount distinct nonempty subsequences, identified by position sets, in which every two consecutive terms differ.	Medium7	Dynamic programmingCombinatorics+1	No attempts yet	2s	512 MB	Judgeable
SweetsPartition n boxes (n up to 24) of sweets into three groups with sums A <= D <= B, minimizing B - A.	Medium7	Brute forceGreedy+2	No attempts yet	2s	512 MB	Judgeable
(K, N)-KnightGiven K, N and two squares, decide whether a generalized knight that jumps K and N squares in either order can travel between them.	Medium7	MathNumber theory+2	No attempts yet	1s	128 MB	Judgeable
DiceGiven n and k, find the number of ways n fair dice can sum to k, then output the integer part of 100 times that probability.	Medium7	Dynamic programmingCombinatorics+2	No attempts yet	1s	128 MB	Judgeable
PawnGiven a large board colored by row intervals, answer whether two squares lie in the same connected same-color region under 8-directional moves.	Medium7	Union-findIntervals+2	No attempts yet	1s	192 MB	Judgeable
Byteantean TownsFor each of n lines, report the absolute difference between the numbers of intersection points on its two sides.	Medium7	GeometrySorting+2	No attempts yet	1s	128 MB	Judgeable
Circular GameOn a circular board, white and black pieces slide over empty runs; decide with optimal play which side wins or whether play can go on forever.	Medium7	Game theoryArray+2	No attempts yet	1s	128 MB	Judgeable
Type Two de Bruijn SequencesGiven a binary string, append the fewest digits so that every length-n binary word appears as a subsequence.	Medium7	GreedyString+1	No attempts yet	2s	512 MB	Judgeable
StudiesGiven a directed graph with edge weights, find every vertex that lies on a closed walk of positive total weight.	Medium7	GraphShortest path+1	No attempts yet	1s	128 MB	Judgeable
MosaicismFor each phage, count ordered pairs of genes and pairs of other phages where one gene has a homolog in one phage and the other gene has a homolog in the other.	Medium7	CombinatoricsBit manipulation+1	No attempts yet	1s	128 MB	Judgeable
PotatoA convex polygon loses one piece per straight cut; maximize the remaining area after at most k cuts while removing every original rind point.	Medium7	GeometryDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
Sport ClubsGiven k partial rankings of n teams, find the permutation of all n teams minimizing the total L1 distance to all the league point vectors.	Medium7	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
BusesGiven bus timetables at every stop, pick an outbound bus and an inbound bus to minimize John's total waiting time before his friend arrives, returning by the friend's arrival time.	Medium7	SortingBinary search+2	No attempts yet	1s	128 MB	Judgeable
BarricadesOn a tree, for each size k find the minimum number of edges to cut so that some connected component has exactly k vertices and no edges leave it.	Medium7	TreeDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
Straight Lines 2Given a possibly self-intersecting polygon and several lines, find the squared distance from each line to the polygon and print it as an exact irreducible fraction.	Medium7	GeometryMath+2	No attempts yet	1s	128 MB	Judgeable
SunsetsFor each cell of an n x n grid, output the tallest height among all cells within Manhattan distance k.	Medium7	Dynamic programmingPrefix sum+1	No attempts yet	1s	128 MB	Judgeable
Farmer's FieldCount placements of a c-by-d or d-by-c rectangle fully inside a field whose every row is one contiguous segment.	Medium7	Sliding windowStack+2	No attempts yet	1s	128 MB	Judgeable
WordsGiven a word of length n, find the smallest number of blocks in a word that differs from it in at most k positions.	Medium7	Dynamic programmingString	No attempts yet	1s	128 MB	Judgeable
AntCount walks of exactly k edges from one cube vertex to another, never reusing the edge just used, modulo p.	Medium7	MatrixDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
Professor Laugh's NumbersGiven a prime p, exponent e, and queries n, decide whether n is an e-th power residue modulo p.	Medium7	Number theoryMath+2	No attempts yet	1s	128 MB	Judgeable
Strong-boxGiven the current knob and bolt positions and the coupling matrix modulo a prime, find the knob configuration that sets all bolts to zero.	Medium7	MathMatrix+2	No attempts yet	1s	128 MB	Judgeable
RooksGiven an n x n 0/1 board, decide whether the number of ways to place n non-attacking rooks on the 1-cells is odd or even.	Medium7	CombinatoricsMath+2	No attempts yet	1s	128 MB	Judgeable
Bus LinesPartition the edges of a connected undirected graph into the fewest trails, where a trail may revisit cities but not edges.	Medium7	GraphGreedy+1	No attempts yet	1s	128 MB	Judgeable
Space Base ConstructionFor each query rectangle, decide if its center lies on some platform or if at least three of its four corners lie on platforms.	Medium7	GeometryBinary search+1	No attempts yet	1s	128 MB	Judgeable
Ball Boxesn boxes in a row hold equal red and green balls with two adjacent empties; repeatedly move two balls into those empties and output a sequence that groups all reds before all greens.	Medium7	GreedySimulation+2	No attempts yet	1s	128 MB	Judgeable
RoadsGiven a directed graph, find the minimum number of edges to add so the whole graph becomes strongly connected.	Medium7	GraphDFS+1	No attempts yet	1s	128 MB	Judgeable
BilliardsDecide which of six table pockets a frictionless bouncing ball reaches, or report that it never falls in.	Medium7	MathNumber theory+2	No attempts yet	1s	128 MB	Judgeable
Critical Computers of the Byteland Information AgencyGiven a directed graph where every node is reachable from node 1, find all vertices whose removal makes some other vertex unreachable from node 1.	Medium7	GraphDFS+1	No attempts yet	1s	128 MB	Judgeable
ParenthesesFlip or query bracket words under updates; answer whether the current string is a correct bracket expression.	Medium7	Segment treeImplementation	No attempts yet	1s	128 MB	Judgeable
Supernumbers in a PermutationGiven a permutation, find every value that appears in some longest increasing subsequence, and print them in increasing order.	Medium7	Dynamic programmingBinary search+1	No attempts yet	1s	128 MB	Judgeable
TomkiGiven two nonzero move vectors, find the minimum Manhattan distance from the origin to any nonzero lattice point reachable by integer combinations of them.	Medium7	MathNumber theory+2	No attempts yet	1s	128 MB	Judgeable
Interplanetary VacationFor each of n planets, compute the Manhattan distance to the farthest planet.	Medium7	MathBit manipulation+2	No attempts yet	1s	128 MB	Judgeable
ChocolateAn impartial chocolate-splitting game where eating the marked square loses. Count the squares whose marking makes the first player lose.	Medium7	Game theoryMath+1	No attempts yet	1s	128 MB	Judgeable
Highway Construction PlanChoose a spanning tree of a connected weighted graph that uses at most d edges incident to vertex 1, minimizing total cost.	Medium7	GraphMinimum spanning tree+1	No attempts yet	1s	192 MB	Judgeable
Physical EducationJasio can skip up to k duels where he is the left student; find the leftmost final position he can reach.	Medium7	ArrayDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
Land SwindleFor each meadow square choose at most one rectangle ending there, maximize the total perimeter, where each rectangle must contain only meadow squares.	Medium7	Dynamic programmingPrefix sum+1	No attempts yet	1s	128 MB	Judgeable
TramsGiven a weighted tree, pair up the leaf nodes choosing disjoint simple paths to minimize or maximize the total length.	Medium7	TreeDynamic programming+1	No attempts yet	1s	128 MB	Judgeable
Divisor GameFor each divisor d of N below N, players Bajtus and Bitus get scores a(d), b(d) when they write d; find the first player's advantage under optimal play when each boy starts.	Medium7	Dynamic programmingGame theory+2	No attempts yet	1s	128 MB	Judgeable
VacationChoose vacation days from a 3n-day forecast, taking at most k days in every window of n consecutive days, to maximize the total temperature.	Medium7	Dynamic programmingSliding window+2	No attempts yet	1s	128 MB	Judgeable
MonopolyGiven points on a grid, connect two points with an edge when their Manhattan distance is at most c; report the number of connected components and the largest component size.	Medium7	GraphUnion-find+2	No attempts yet	1s	128 MB	Judgeable
TowerPartition the sequence of brick widths into consecutive blocks so that block sums do not increase from bottom to top, maximizing the number of blocks.	Medium7	Dynamic programmingGreedy+2	No attempts yet	1s	128 MB	Judgeable
TrianglesFor each range query on a sequence, decide whether the range contains three values that satisfy the strict triangle inequality.	Medium7	SortingGreedy+2	No attempts yet	1s	128 MB	Judgeable
Two PostmenSplit the edges of a tree rooted at node 1 between two postmen starting at the root so the later finishing time is minimized.	Medium7	TreeDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
Highway ModernizationPick highways linking city 1 to city 2 to minimize total cost over total length, and print the ratio as a reduced fraction.	Medium7	Shortest pathBinary search+1	No attempts yet	1s	128 MB	Judgeable
Fiber Optic NetworkReserve bandwidth on tree paths for connect requests when capacity allows and release per-pair reservations on disconnect.	Medium7	Segment treeTree+1	No attempts yet	1s	128 MB	Judgeable