Problems

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Total results29,423 problems

Rockets
Hard8
Dynamic programming, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Altars
Hard8
Geometry, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Painter's Studio
Hard8
Divide and conquer, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Polygon
Hard8
Geometry, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Word Equations
Hard8
String, Union-find+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Window
Hard8
Geometry, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Assembler Circuits
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Chase
Hard8
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Lightest Language
Hard8
Tree, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Flat Broken Lines
Hard8
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Addon
Hard8
Number theory, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Credibility of Witnesses
Hard8
Graph, Union-find+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ali Baba
Hard8
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Containers
Hard8
BFS, Graph
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Castle
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Rooks
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Disk Optimization
Hard8
Sorting, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Step Traversing a Tree
Hard8
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Warehouse
Hard8
Geometry, Binary search+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Schools
Hard8
Greedy, Dynamic programming+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Subway
Hard8
Tree, Dynamic programming+1
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
The Invasion
Hard8
Geometry, Two pointers+2
No attempts yet
Time limit
3s
Memory limit
64 MB
Judgeable
The Postman
Hard8
Graph, DFS+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ploughing
Hard8
Dynamic programming, Two pointers+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Dancing in Circles
Hard8
Combinatorics, Math+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Crystals
Hard8
Bit manipulation, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sophie's Birthday Party
Hard8
Graph, Greedy+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Tourist Attractions
Hard8
Shortest path, Dynamic programming+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Rock Garden
Hard8
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tetris Attack
Hard8
Greedy, Stack+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Gas Pipelines
Hard8
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Quaternary Balance
Hard8
Dynamic programming, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Mirror Trap
Hard8
Geometry, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Plot purchase
Hard8
Prefix sum, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fire Extinguisher Installation
Hard8
Tree, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Elephants
Hard8
Greedy, Graph+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
The Walk of Bytie-boy
Hard8
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ice Skates
Hard8
Segment tree, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Words 2
Hard8
String, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Words
Hard8
String, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Beads
Hard8
String, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Divine Divisor
Hard8
Number theory, Math+1
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Antisymmetry
Hard8
String, Hash map+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Sheep
Hard8
Dynamic programming, Geometry+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
King Sejong
Hard8
Graph, Greedy+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Monotonicity 2
Hard8
Dynamic programming, Segment tree+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Lamp
Hard8
Geometry, Implementation+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Frog
Hard8
Two pointers, Binary search+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Lightning Conductor
Hard8
Divide and conquer, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Plot
Hard8
Binary search, Dynamic programming+2
No attempts yet
Time limit
30s
Memory limit
128 MB
Judgeable
Tree Rotations 2
Hard8
Divide and conquer, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Dynamite
Hard8
Tree, Binary search+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Inspection
Hard8
Tree, DFS+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Meteors
Hard8
Binary search, Prefix sum+2
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Festival
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Prime Factor Distance
Hard8
Number theory, Graph+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Rendezvous
Hard8
Graph, Binary search+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Digging a Well
Hard8
Binary search, Greedy
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Vouchers
Hard8
Number theory, Math+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
A Horrible Poem
Hard8
String, Number theory+2
No attempts yet
Time limit
8s
Memory limit
128 MB
Judgeable
Fibonacci Representation
Hard8
Dynamic programming, Math+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Squarks
Hard8
Sorting, Brute force+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Salaries
Hard8
Tree, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Leveling Ground
Hard8
Math, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Minimalist Security
Hard8
Graph, DFS+2
No attempts yet
Time limit
4s
Memory limit
128 MB
Judgeable
Warehouse Store
Hard8
Greedy, Heap+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Prefixuffix
Hard8
String, String matching+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Price List
Hard8
Graph, BFS+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Tapestries
Hard8
Geometry, Divide and conquer
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Inspector
Hard8
Intervals, Brute force+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Triumphal Arch
Hard8
Tree, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Byteotian War
Hard8
Dynamic programming, Game theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Painting the Wall
Hard8
Sorting, Segment tree+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Scissors
Hard8
Geometry, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cheap Airlines
Hard8
Dynamic programming, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fosa
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bark Beetles
Hard8
Dynamic programming, Game theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Travel Tax
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Transformations
Hard8
String, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Unlucky
Hard8
Math, Greedy
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pedestrian Crossing
Hard8
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fuel
Hard8
Tree, DFS+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Plotter
Hard8
Recursion, Divide and conquer+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Declining Sequences
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Trails
Hard8
Divide and conquer, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Vacation
Hard8
Dynamic programming, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Number of Tree Automorphisms
Hard8
Tree, DFS+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Laser Pool
Hard8
Math, Simulation+2
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
The Shortest Period
Hard8
String, String matching+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Byteland Worldbeat Publishers
Hard8
Graph, Greedy+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Coprime Numbers
Hard8
Number theory, Combinatorics+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Telescope
Hard8
Dynamic programming, Sorting+1
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Mushrooms
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Map 2
Hard8
Sorting, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Termites
Hard8
Greedy, Game theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Firm
Hard8
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Divisors
Hard8
Number theory, Tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Byteball Match
Hard8
Graph, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Termites 2
Hard8
Game theory, Tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The Way to Bytemountain
Hard8
Graph, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
32 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
RocketsMatch the n red points to the n white points with non-crossing segments so the total Euclidean length is minimum, and report the matching.	Hard8	Dynamic programmingDivide and conquer+2	No attempts yet	1s	128 MB	Judgeable
AltarsFor each rectangle temple, decide whether a ray from its center can exit through the half-wall entrance and escape to infinity without touching any rectangle.	Hard8	GeometryImplementation+1	No attempts yet	1s	128 MB	Judgeable
Painter's StudioCount the number of positions where a hole in one self-similar fractal matrix coincides with a hole in the same matrix shifted by (x, y).	Hard8	Divide and conquerRecursion+2	No attempts yet	1s	128 MB	Judgeable
PolygonGiven a convex polygon and its triangulation, find the maximum number of triangulation triangles a single elementary triangle can intersect.	Hard8	GeometryDynamic programming+1	No attempts yet	1s	128 MB	Judgeable
Word EquationsCount the binary word assignments to variables of fixed lengths that make the two sides of a word equation equal.	Hard8	StringUnion-find+2	No attempts yet	1s	128 MB	Judgeable
WindowGiven an orthogonal polygon and an axis-parallel window, count how many separate interior fragments of the polygon are visible through the window.	Hard8	GeometryImplementation+1	No attempts yet	1s	128 MB	Judgeable
Assembler CircuitsGiven a straight-line program of register assignments, find the fewest binary-operation gates needed to compute all final register values for every initial state.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	128 MB	Judgeable
ChaseOn a triangle-free connected board, decide whether chaser B can force a catch of runner A and, if so, the minimum number of turns needed.	Hard8	GraphBFS+2	No attempts yet	1s	128 MB	Judgeable
The Lightest LanguageGiven n, k, and letter weights, find the minimum total weight of a prefixless set of exactly n words over k letters.	Hard8	TreeGreedy+2	No attempts yet	1s	128 MB	Judgeable
Flat Broken LinesGiven n points, find the minimum number of flat broken lines (each moving right with segment slopes between -1 and 1) needed to cover all points.	Hard8	GreedySorting+1	No attempts yet	1s	128 MB	Judgeable
AddonGiven the stable heights, find the largest chamber height admitting a safe and complete set of rod lengths, and output a smallest such set.	Hard8	Number theoryCombinatorics+1	No attempts yet	1s	128 MB	Judgeable
Credibility of WitnessesGiven agree/disagree statements between witnesses, find all witnesses whose implied relations force them to both agree and disagree with some other witness.	Hard8	GraphUnion-find+1	No attempts yet	1s	128 MB	Judgeable
Ali BabaGiven starting tokens and trade rules over three token types, find the minimum number of trades to reach at least the required counts per type, or NIE if impossible.	Hard8	BFSGraph+2	No attempts yet	1s	128 MB	Judgeable
ContainersGiven up to four full containers, decide if a target water distribution is reachable using whole pours, fill-ups, and drains, and find the minimum number of moves.	Hard8	BFSGraph	No attempts yet	1s	128 MB	Judgeable
CastleGiven an orthogonal simple polygon with corridor grid lines inside it, find the shortest path along grid lines between two marked lattice points.	Hard8	GraphShortest path+1	No attempts yet	1s	128 MB	Judgeable
RooksPlace n non-attacking rooks, one per given axis-aligned rectangle, or report that no placement exists; output the lexicographically smallest placement.	Hard8	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
Disk OptimizationGiven disk sectors holding files split across blocks, find the minimum copy/swap cost to pack files into consecutive sorted blocks.	Hard8	SortingGreedy+1	No attempts yet	1s	128 MB	Judgeable
Step Traversing a TreeGiven a tree on n vertices, find the smallest c such that the vertices can be visited in some order where each consecutive pair is at distance at most c.	Hard8	TreeDFS+2	No attempts yet	1s	128 MB	Judgeable
WarehouseFind a crossroads minimizing the weighted sum of Chebyshev distances to n shops.	Hard8	GeometryBinary search+2	No attempts yet	1s	128 MB	Judgeable
SchoolsAssign a distinct number 1..n to each school within its allowed interval, minimizing the total weighted movement cost.	Hard8	GreedyDynamic programming+2	No attempts yet	3s	128 MB	Judgeable
SubwayGiven a tree with n stations, choose l non-branching paths (routes) to cover as many distinct vertices as possible.	Hard8	TreeDynamic programming+1	No attempts yet	3s	128 MB	Judgeable
The InvasionGiven a convex polygon with n vertices and m weighted points, find three polygon vertices forming a triangle with the maximum total weight of points inside or on it.	Hard8	GeometryTwo pointers+2	No attempts yet	3s	64 MB	Judgeable
The PostmanDecide whether a directed graph has an Euler circuit from node 1 that contains each given sequence as a contiguous run of the route.	Hard8	GraphDFS+1	No attempts yet	1s	128 MB	Judgeable
PloughingGiven an m by n grid of tile difficulties, repeatedly remove a full strip of width 1 from any edge as long as the strip sum is at most k, and minimize the number of strips that remove every tile.	Hard8	Dynamic programmingTwo pointers+2	No attempts yet	1s	128 MB	Judgeable
Dancing in CirclesCount ways to split n labeled children into k unordered directed cycles of length at least l, modulo 2005.	Hard8	CombinatoricsMath+2	No attempts yet	3s	512 MB	Judgeable
CrystalsCount tuples a_i with 0 <= a_i <= m_i whose XOR is zero and whose sum is at least 1, with n <= 50 and bounds near 2^32.	Hard8	Bit manipulationDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
Sophie's Birthday PartyGiven objections between kids, find the largest set with no objection inside it, i.e. the maximum independent set, or NIE if it is below k.	Hard8	GraphGreedy+2	No attempts yet	3s	128 MB	Judgeable
Tourist AttractionsFind the shortest route from site 1 to site n that visits sites 2 through k+1 in some order consistent with given precedence constraints.	Hard8	Shortest pathDynamic programming+2	No attempts yet	3s	128 MB	Judgeable
Rock GardenEach boulder may keep or swap its two coordinates; choose swaps so the axis-aligned bounding rectangle perimeter is minimal, then minimize total swapped weight.	Hard8	GreedySorting+1	No attempts yet	1s	128 MB	Judgeable
Tetris AttackA stack holds each of n symbols twice; adjacent equal pairs vanish on contact, and one move swaps neighboring elements. Find the minimum swaps to empty the stack.	Hard8	GreedyStack+2	No attempts yet	1s	128 MB	Judgeable
Gas PipelinesAssign each of n extraction points to a distinct station southeast of it, minimizing the total Manhattan distance.	Hard8	GreedySorting+1	No attempts yet	1s	128 MB	Judgeable
Quaternary BalanceGiven n up to 1000 digits, count modulo 10^9 the distinct minimum-mass weighings of n grams with masses that are powers of four, placed on either pan or both.	Hard8	Dynamic programmingMath+2	No attempts yet	1s	128 MB	Judgeable
Mirror TrapGiven a rectilinear polygon, pair up its corners by tracing 45-degree laser beams that reflect off mirror walls until each beam lands in another corner.	Hard8	GeometrySimulation+2	No attempts yet	1s	128 MB	Judgeable
Plot purchaseGiven an n by n grid of non-negative prices, decide whether some axis-aligned subrectangle has a sum between k and 2k inclusive.	Hard8	Prefix sumGreedy+2	No attempts yet	1s	128 MB	Judgeable
Fire Extinguisher InstallationPlace extinguishers on tree rooms, each covering at most S rooms within distance K, so every room is covered; minimize the count.	Hard8	TreeGreedy+1	No attempts yet	1s	128 MB	Judgeable
ElephantsGiven elephant masses and two permutations, find the minimum total cost of swaps (cost = sum of the two masses) to convert the first order into the second.	Hard8	GreedyGraph+2	No attempts yet	3s	512 MB	Judgeable
The Walk of Bytie-boyFor each consecutive pair of stops in a city of one-way lettered streets, find the shortest walk whose letter sequence is a palindrome, tie-broken by lexicographically smallest string.	Hard8	BFSGraph+2	No attempts yet	1s	128 MB	Judgeable
Ice SkatesAfter each of m membership events, decide whether every current member can be assigned skates, given k pairs of each size and foot sizes with tolerance d.	Hard8	Segment treeGreedy+1	No attempts yet	1s	128 MB	Judgeable
Words 2Given exponents k1..kn, find the smallest m such that the concatenation of h_k(0) is a substring of h_m(0), or report NIE.	Hard8	StringRecursion+2	No attempts yet	1s	128 MB	Judgeable
WordsGiven indices k_i, decide whether the concatenation of the words h^{k_i}(0) appears as a substring of some h^m(0).	Hard8	StringDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
BeadsSplit the bead string into blocks of size k (leftover dropped) and find the k that maximizes the count of distinct blocks, where a block and its reversal are the same.	Hard8	StringHash map+2	No attempts yet	1s	128 MB	Judgeable
Divine DivisorGiven n numbers whose product is N, report the maximum multiplicity of any divisor and how many divisors achieve it.	Hard8	Number theoryMath+1	No attempts yet	3s	128 MB	Judgeable
AntisymmetryCount how many contiguous substrings of a binary string are antisymmetric, meaning each character differs from its mirror-position partner.	Hard8	StringHash map+2	No attempts yet	3s	512 MB	Judgeable
SheepCount triangulations of a convex n-gon by non-crossing diagonals such that no diagonal passes through a sheep's spot and every triangle holds an even number of spots, modulo m.	Hard8	Dynamic programmingGeometry+2	No attempts yet	3s	512 MB	Judgeable
King SejongGiven a graph where no path from 1 to 2 uses fewer than 4 edges, find the maximum number of edges that can be added while keeping the 1-to-2 distance at least 5.	Hard8	GraphGreedy+2	No attempts yet	3s	512 MB	Judgeable
Monotonicity 2Find the longest subsequence of a given array whose adjacent-comparison pattern repeats the given cyclic scheme of <, >, = symbols.	Hard8	Dynamic programmingSegment tree+1	No attempts yet	3s	512 MB	Judgeable
LampGiven rectangular windows on two parallel walls 10 m apart and a lamp on one wall, count the windows of the lamp's building whose interior any reflected ray can reach.	Hard8	GeometryImplementation+2	No attempts yet	5s	512 MB	Judgeable
FrogFor each rock, find where a frog lands after exactly m leaps, where each leap goes to the k-th nearest rock with ties broken toward the spring.	Hard8	Two pointersBinary search+1	No attempts yet	3s	512 MB	Judgeable
Lightning ConductorFor each building i, find the smallest integer p such that h_i + p - sqrt(\|i-j\|) >= h_j for every building j.	Hard8	Divide and conquerDynamic programming+1	No attempts yet	1s	128 MB	Judgeable
PlotPartition a sequence of n points into at most m contiguous groups, replacing each group with one point, to minimize the maximum distance from any original point to its group's representative.	Hard8	Binary searchDynamic programming+2	No attempts yet	30s	128 MB	Judgeable
Tree Rotations 2Given a binary tree with distinct leaf labels, rotations swap children at any node; find the minimum possible inversion count of the leaf sequence.	Hard8	Divide and conquerRecursion+2	No attempts yet	1s	128 MB	Judgeable
DynamiteLight the fuses in exactly m chambers of a tree so that every charge-detonation is covered as early as possible, and report the last detonation time.	Hard8	TreeBinary search+2	No attempts yet	2s	128 MB	Judgeable
InspectionFor each root of a tree, find the minimum time for a tour that inspects every node and returns to the root each time, with no two consecutive trips using the same first edge.	Hard8	TreeDFS+2	No attempts yet	5s	128 MB	Judgeable
MeteorsEach of N states owns sectors on a circle; given Q meteor showers that add a value to a sector range, find the earliest day each state's total reaches its target, or report it never does.	Hard8	Binary searchPrefix sum+2	No attempts yet	5s	256 MB	Judgeable
FestivalGiven exact +1 edges and <= edges between runners' integer times, find the maximum count of distinct times consistent with all constraints, or NIE if impossible.	Hard8	GraphShortest path+1	No attempts yet	3s	128 MB	Judgeable
Prime Factor DistanceFor each element in a sequence, find the other index minimizing the prime-factor multiset distance, where one operation multiplies or divides by a prime, breaking ties by smallest index.	Hard8	Number theoryGraph+2	No attempts yet	3s	128 MB	Judgeable
RendezvousEach node has one outgoing edge; for k queries (a, b), find the smallest max step counts x, y with f^x(a) = f^y(b), tie-broken by smaller min.	Hard8	GraphBinary search+2	No attempts yet	5s	128 MB	Judgeable
Digging a WellGiven depths x_i and m total decrements, find the leftmost position where a value can reach 0 while minimizing the maximum adjacent difference.	Hard8	Binary searchGreedy	No attempts yet	1s	128 MB	Judgeable
VouchersEach day k removes the a_k smallest remaining package sizes divisible by a_k; report which customers buy packages that hold vouchers.	Hard8	Number theoryMath+2	No attempts yet	3s	128 MB	Judgeable
A Horrible PoemGiven a string and substring queries, find the length of the shortest full period of each substring, where a full period divides the substring into equal repeats.	Hard8	StringNumber theory+2	No attempts yet	8s	128 MB	Judgeable
Fibonacci RepresentationFor each query k, find the fewest Fibonacci numbers whose signed sum (plus or minus, repeats allowed) equals k.	Hard8	Dynamic programmingMath+2	No attempts yet	3s	128 MB	Judgeable
SquarksGiven the n(n-1)/2 pairwise sums of n distinct positive integers, find and list all sets of n integers whose pairwise sums match these values, in lexicographic order.	Hard8	SortingBrute force+2	No attempts yet	2s	128 MB	Judgeable
SalariesGiven a rooted tree with salaries a permutation of 1 to n increasing toward the root and some values revealed, print each value forced by the revealed ones or 0 otherwise.	Hard8	TreeGreedy+2	No attempts yet	1s	128 MB	Judgeable
Leveling GroundFind the fewest range operations, adding or subtracting a or b on any contiguous stretch, that turn all n ground heights into zero.	Hard8	MathGreedy+2	No attempts yet	1s	128 MB	Judgeable
Minimalist SecurityEach vertex v loses z(v) officers with 0 <= z(v) <= p(v), and every edge uv must end with exactly p(u)-z(u)+p(v)-z(v) = b(u,v); find the min and max of the total sum of z(v), or report impossible.	Hard8	GraphDFS+2	No attempts yet	4s	128 MB	Judgeable
Warehouse StoreGiven daily deliveries a_i and daily orders b_i, choose which orders to accept so that the warehouse never runs out of stock, maximizing accepted orders.	Hard8	GreedyHeap+2	No attempts yet	1s	128 MB	Judgeable
PrefixuffixGiven a string t, find the maximum length L, at most n/2, such that the length-L prefix and the length-L suffix of t are cyclic rotations of each other.	Hard8	StringString matching+2	No attempts yet	3s	512 MB	Judgeable
Price ListGiven a rail graph, add flight edges between towns at rail distance two but not adjacent, then find cheapest costs from a source mixing rail and air fares.	Hard8	GraphBFS+2	No attempts yet	3s	512 MB	Judgeable
TapestriesDecide whether a point strictly inside a simple polygon sees each edge as entirely lit or entirely dark, matching a given lit/dark pattern per wall.	Hard8	GeometryDivide and conquer	No attempts yet	1s	128 MB	Judgeable
InspectorGiven statements of the form 'at time t, programmer j was present along with i others', find the largest prefix of statements that can all hold at once.	Hard8	IntervalsBrute force+2	No attempts yet	5s	128 MB	Judgeable
Triumphal ArchGiven a tree rooted at town 1, find the minimum number of crews so that each town gets its arch built before the king's first arrival, where the king's walk is unknown.	Hard8	TreeGreedy+2	No attempts yet	1s	128 MB	Judgeable
The Byteotian WarBoth players take turns discarding one of their top two cards and passing the other to the opponent; find the final score when both play optimally.	Hard8	Dynamic programmingGame theory+2	No attempts yet	1s	128 MB	Judgeable
Painting the WallGiven n axis-aligned rectangles, find the total area of the plane covered by at least n-1 of them.	Hard8	SortingSegment tree+2	No attempts yet	1s	128 MB	Judgeable
ScissorsGiven a rectilinear simple polygon, find the minimum number of drawn segments (each with endpoints on the boundary and interior inside) so that cutting along them makes every piece a rectangle.	Hard8	GeometryGraph+2	No attempts yet	1s	128 MB	Judgeable
Cheap AirlinesChoose at most k non-overlapping contiguous segments of the array to maximize the total sum of their elements.	Hard8	Dynamic programmingGreedy+1	No attempts yet	1s	128 MB	Judgeable
FosaGiven horizontal and vertical segments, find the largest axis-aligned square whose entire perimeter lies on those segments, or report that none exists.	Hard8	GeometrySorting+1	No attempts yet	1s	128 MB	Judgeable
Bark BeetlesTwo beetles alternate taking one end picket or both end pickets from a row; each maximizes its own total, so find both final totals.	Hard8	Dynamic programmingGame theory+2	No attempts yet	1s	128 MB	Judgeable
Travel TaxFind a path from city 1 to n minimizing the sum, over visited cities, of the maximum road rate entering and leaving that city.	Hard8	GraphShortest path+2	No attempts yet	3s	256 MB	Judgeable
TransformationsGiven two binary strings of length n, decide whether disjoint ab and ba fragments can be swapped repeatedly to turn the first string into the second.	Hard8	StringMath+2	No attempts yet	1s	128 MB	Judgeable
UnluckyFind how much water a traveler can deliver to an oasis s meters away, given w total water and carry limit k.	Hard8	MathGreedy	No attempts yet	1s	128 MB	Judgeable
Pedestrian CrossingDecide whether a shoe of length s, stepping by k, can cross stripes of given widths while never overlapping a white stripe.	Hard8	MathNumber theory+2	No attempts yet	1s	128 MB	Judgeable
FuelFind the maximum number of distinct vertices of a tree that can be visited by a walk of length at most m edges.	Hard8	TreeDFS+1	No attempts yet	1s	128 MB	Judgeable
PlotterGiven the recursively defined order-n bytecurve and m integer points, report how many times and at which seconds the pen visits each point.	Hard8	RecursionDivide and conquer+2	No attempts yet	5s	128 MB	Judgeable
Declining SequencesGiven a sequence and a fixed length p, count and return the lexicographically k-th decreasing index sequence for each query.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	1s	128 MB	Judgeable
TrailsFor each axis-aligned unit-height tape, count the connected pieces of the bytecurve of order n that lie inside the rectangle.	Hard8	Divide and conquerRecursion+2	No attempts yet	1s	128 MB	Judgeable
VacationFind a permutation of n attractions minimizing the total capped positional distance to k given rankings (k at most 3).	Hard8	Dynamic programmingSorting+1	No attempts yet	1s	128 MB	Judgeable
Number of Tree AutomorphismsCount the automorphisms of a tree modulo 1e9+7.	Hard8	TreeDFS+2	No attempts yet	5s	128 MB	Judgeable
Laser PoolA ball bounces elastically around a grid of lit horizontal and vertical laser beams; count how many distinct lit beams it touches during t time units, including the start.	Hard8	MathSimulation+2	No attempts yet	5s	256 MB	Judgeable
The Shortest PeriodDelete exactly one letter from a string to minimize the length of the shortest period of the resulting word.	Hard8	StringString matching+2	No attempts yet	5s	128 MB	Judgeable
Byteland Worldbeat PublishersGiven a sparse matrix of pair efficiencies (some described by row-wise column ranges), decide whether all maximum-size matchings have the same total weight.	Hard8	GraphGreedy+2	No attempts yet	5s	128 MB	Judgeable
Coprime NumbersGiven up to a million integers, count pairs whose greatest common divisor is 1.	Hard8	Number theoryCombinatorics+2	No attempts yet	5s	128 MB	Judgeable
TelescopeChoose an order for the coins and insertion times so that the paid viewing windows cover as many meteor intervals as possible.	Hard8	Dynamic programmingSorting+1	No attempts yet	5s	128 MB	Judgeable
MushroomsA walker starts at glade 1, moves one glade every 15 minutes for t moves, picks all mushrooms on arrival, and each glade regrows 30 minutes later; maximize the total harvest.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	128 MB	Judgeable
Map 2Count integer starting points (a,b) such that each of the four diagonal quadrants around (a,b) contains at least one of n marked points.	Hard8	SortingPrefix sum+2	No attempts yet	1s	128 MB	Judgeable
TermitesTwo termites alternately eat planks adjacent to already-eaten ones, each maximizing her total; report the wood each ends up with under optimal play.	Hard8	GreedyGame theory+2	No attempts yet	2s	512 MB	Judgeable
FirmProcess hires and queries on a growing rooted tree, counting employees at exact depth offset k below a given node at query time.	Hard8	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
DivisorsGiven n and an expression built from divisors of n with gcd and lcm, decide whether the expression's value is the same for every assignment of variables.	Hard8	Number theoryTree+2	No attempts yet	2s	512 MB	Judgeable
Byteball MatchGiven partial results of a round-robin group, list every team that can still finish first once all remaining matches are played, under points and goal-difference tiebreaks.	Hard8	GraphBrute force+2	No attempts yet	2s	512 MB	Judgeable
Termites 2Given a tree with its edges ordered, two players alternately remove an uneaten endpoint of the next edge; report the round the loser is forced and loses, or -1 for a draw.	Hard8	Game theoryTree+2	No attempts yet	2s	512 MB	Judgeable
The Way to BytemountainFind a walk from crossing 1 to crossing n that deviates from the signpost arrows at most k times and maximizes total trail beauty.	Hard8	GraphDynamic programming+2	No attempts yet	1s	32 MB	Judgeable