Problems

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Total results29,413 problems

Jumbled Journey
Hard8
Graph, Topological sort+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Paris by Night
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
15s
Memory limit
512 MB
Judgeable
Travel Guide
Hard8
Shortest path, Graph+2
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Dishonest Driver
Hard8
Dynamic programming, String+2
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Garden Variety Vampire
Hard8
Geometry, Bit manipulation+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Balance Scale
Hard8
Math, Hash map+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Flipping Colors
Hard8
Minimum spanning tree, Graph+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Running Routes
Hard8
Dynamic programming, Intervals+2
No attempts yet
Time limit
12s
Memory limit
1024 MB
Judgeable
Stop Counting!
Hard8
Math, Prefix sum+2
No attempts yet
Time limit
7s
Memory limit
1024 MB
Judgeable
Gifted Bafuko
Hard8
Tree, Graph+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Sequence and Queries 31
Hard8
Segment tree, Intervals+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Shopping Mall
Hard8
Simulation, Heap+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Frog Jump
Hard8
Geometry, Union-find+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Drone
Hard8
BFS, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Brackets
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Black Stones
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
XORanges
Hard8
Bit manipulation, Segment tree+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Strange Machine
Hard8
Math, Number theory+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Bridges
Hard8
Divide and conquer, Union-find+1
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Street Lights
Hard8
Segment tree, Implementation
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Separator
Hard8
Tree, Implementation+2
No attempts yet
Time limit
1.2s
Memory limit
512 MB
Judgeable
Amusement Park
Hard8
Bit manipulation, Dynamic programming+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Magic Tree
Hard8
Tree, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sum of Squares 2 (More Huge)
Hard8
Math, Number theory+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Majorant
Hard8
Array, Segment tree+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Namuhs
Hard8
Divide and conquer, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Resistance
Hard8
Graph, Minimum spanning tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Triple Jump
Hard8
Divide and conquer, Segment tree+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Exam
Hard8
Sorting, Prefix sum+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Two Antennas
Hard8
Segment tree, Stack+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Special Tourist City
Hard8
Tree, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Time-Traveling Vitaro
Hard8
Segment tree, Intervals+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Cake 3
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
4s
Memory limit
256 MB
Judgeable
Merge
Hard8
Tree, DFS+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Minerals
Hard8
Divide and conquer, Implementation+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Construction of Highway
Hard8
Tree, Segment tree+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Fences
Hard8
Geometry, Shortest path+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Tents
Hard8
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Worst Reporter 3
Hard8
Segment tree, Sorting+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Library
Hard8
Intervals, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Wild Boar
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Cultivation
Hard8
Binary search, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Broken Device
Hard8
Bit manipulation, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Railway Trip
Hard8
Array, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Dragon 2
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Matryoshka
Hard8
Sorting, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Telegraph
Hard8
Graph, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Copy and Paste 2
Hard8
Implementation, Binary search+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
JOI Logo Design
Hard8
Dynamic programming, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Growing Vegetables is Fun 2
Hard8
Dynamic programming, Tree+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
IOIOI Cards
Hard8
Shortest path, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Building 3
Hard8
Dynamic programming, Array+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Inheritance
Hard8
Graph, Union-find+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Walls
Hard8
Dynamic programming, Greedy
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Bus
Hard8
Graph, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Growing Vegetables is Fun
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Making Friends is Fun
Hard8
Graph, Union-find+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Scarecrows
Hard8
Sorting, Divide and conquer+1
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Constellation 2
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
9s
Memory limit
512 MB
Judgeable
Collecting Images is Fun
Hard8
Divide and conquer, Implementation+2
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Communication Jamming
Hard8
Union-find, Graph+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Mascots
Hard8
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Spy
Hard8
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Cake
Hard8
Greedy, Union-find+1
No attempts yet
Time limit
1.5s
Memory limit
256 MB
Judgeable
White Day Present Exchange
Hard8
Graph, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Equation
Hard8
Math, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Championships
Hard8
Graph, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cell Explosion
Hard8
String matching, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Robots
Hard8
Matrix, Bit manipulation+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Gym
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
JOI Flag
Hard8
Divide and conquer, Dynamic programming+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Conveyor Belts
Hard8
Math, Number theory+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Inquiry II
Hard8
Tree, DFS+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Estate Agent
Hard8
Graph, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Grand Central Station
Hard8
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hat Stand
Hard8
Greedy, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Mosaic Mansion
Hard8
Dynamic programming, Hash map+2
No attempts yet
Time limit
12s
Memory limit
512 MB
Judgeable
Džumbus
Hard8
Dynamic programming, Tree+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Sequence and Queries 33
Hard8
Dynamic programming, Segment tree+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Dice Yutnori
Hard8
Backtracking, Simulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Lion and Rabbit
Hard8
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Fibonacci Music
Hard8
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Copy and Paste
Hard8
String, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cheese, If You Please
Hard8
Math, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Just Passing Through
Hard8
Dynamic programming, Matrix+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Where Have You Bin?
Hard8
Dynamic programming, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Circle Garden
Hard8
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Integers in Rational Bases
Hard8
Number theory, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Hogwarts
Hard8
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Molecules
Hard8
Graph, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Watch Later
Hard8
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Pairing Socks
Hard8
Stack, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Tree Hugging
Hard8
Graph, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Loo Rolls
Hard8
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Type Charts
Hard8
Math, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Dice and Ladders
Hard8
Probability, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Counting Permutations with a Given Greedily Increasing Subsequence
Hard8
Combinatorics, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Train Tickets
Hard8
Dynamic programming, Divide and conquer+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Logland
Hard8
Bit manipulation, Greedy+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Ranch CCTV
Hard8
Prefix sum, Matrix+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Jumbled JourneyGiven the average length of all paths between each pair of parks in a one-way acyclic park map, rebuild the road lengths of the original map.	Hard8	GraphTopological sort+1	No attempts yet	1s	512 MB	Judgeable
Paris by NightGiven N graded points in general position, pick two boundary monuments and split the rest by the line through them to minimize the absolute difference of the two side sums.	Hard8	GeometrySorting+2	No attempts yet	15s	512 MB	Judgeable
Travel GuideGiven a weighted undirected graph with three special nodes, count the vertices that are not dominated in all three distances by another vertex.	Hard8	Shortest pathGraph+2	No attempts yet	6s	512 MB	Judgeable
Dishonest DriverGiven a string of N characters, find the size of the shortest compressed form built from single characters, concatenation, and repetition (C repeated k times).	Hard8	Dynamic programmingString+2	No attempts yet	6s	512 MB	Judgeable
Garden Variety VampireGiven three points and n circle radii, decide whether the circles can be placed so their union connects all three points.	Hard8	GeometryBit manipulation+1	No attempts yet	1s	512 MB	Judgeable
Balance ScaleGiven a set of existing weights and target amounts, find the lightest single new weight that makes every amount expressible as a signed subset sum of the weights, or report 0 or -1.	Hard8	MathHash map+2	No attempts yet	2s	512 MB	Judgeable
Flipping ColorsGiven a complete graph with red and black penalized edges, where flipping a node flips its incident edges, find the minimum-penalty all-red spanning tree reachable this way, or -1.	Hard8	Minimum spanning treeGraph+1	No attempts yet	3s	512 MB	Judgeable
Running RoutesGiven chords of a convex n-gon, find the largest set of chords no two of which share any common point, including endpoints.	Hard8	Dynamic programmingIntervals+2	No attempts yet	12s	1024 MB	Judgeable
Stop Counting!Given a deck of integers, choose one contiguous block to skip so the average of the remaining cards is maximized.	Hard8	MathPrefix sum+2	No attempts yet	7s	1024 MB	Judgeable
Gifted BafukoGiven the square of an unknown tree with maximum degree 3 as an undirected graph, recover the tree's adjacency list.	Hard8	TreeGraph+1	No attempts yet	10s	512 MB	Judgeable
Sequence and Queries 31Maintain a 0/1 sequence under range reversals, and answer queries for the longest run of 1s inside a given range.	Hard8	Segment treeIntervals+2	No attempts yet	2s	512 MB	Judgeable
Shopping MallSimulate customers choosing the counter with the minimum total wait (lowest index on ties), then compute a weighted sum of membership numbers in the order customers leave.	Hard8	SimulationHeap+2	No attempts yet	1s	512 MB	Judgeable
Frog JumpGiven N disjoint horizontal line segments, two logs are connected if a vertical jump between them crosses no other log; answer queries on whether logs are reachable.	Hard8	GeometryUnion-find+1	No attempts yet	1s	512 MB	Judgeable
DroneA drone moves on an N x N tile maze with walls; LED tiles light up in sequence order as the drone steps on them, and we need the shortest total travel time to display the whole sequence and exit.	Hard8	BFSShortest path+2	No attempts yet	1s	512 MB	Judgeable
BracketsFor each N, find the valid bracket string with bracket value N whose digit-encoded decimal value is smallest, and print it.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	512 MB	Judgeable
Black StonesGiven a tree with some vertices marked black, count how many queries (i, j) admit a connected subtree with exactly i vertices and j black vertices.	Hard8	TreeDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
XORangesMaintain an array under point updates and answer queries for the XOR of every contiguous subarray inside [l, u].	Hard8	Bit manipulationSegment tree+2	No attempts yet	1s	512 MB	Judgeable
Strange MachineCount the distinct pairs (x, y) produced by the map t -> (((t + floor(t/B)) mod A), t mod B) over n disjoint time intervals.	Hard8	MathNumber theory+2	No attempts yet	4s	512 MB	Judgeable
BridgesBridges have weight limits that change over time, and for each query you must count the islands a car of a given weight can reach from its start island.	Hard8	Divide and conquerUnion-find+1	No attempts yet	4s	512 MB	Judgeable
Street LightsGiven n street lights and q toggle or query events, for each query count the total time units up to now when all lights from stop a to stop b are on.	Hard8	Segment treeImplementation	No attempts yet	5s	512 MB	Judgeable
SeparatorAppend values one at a time to a growing sequence and after each append report how many indices are separators, meaning every earlier element is smaller and every later element is larger.	Hard8	TreeImplementation+2	No attempts yet	1.2s	512 MB	Judgeable
Amusement ParkGiven up to 18 attractions and directed slides, sum the number of reversed slides over all direction choices that leave no cycle, modulo 998244353.	Hard8	Bit manipulationDynamic programming+2	No attempts yet	3s	512 MB	Judgeable
Magic TreeGiven a rooted tree where each non-root vertex holds one fruit ripe on a single day, find the maximum juice from cutting branches on chosen days.	Hard8	TreeDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Sum of Squares 2 (More Huge)Given n up to 10^18, find the minimum number of perfect squares summing to n and output the actual square roots used.	Hard8	MathNumber theory+2	No attempts yet	0.5s	512 MB	Judgeable
MajorantGiven an array with point updates, compute the sum of i times the number of subarrays in a query range where i is the majorant, modulo 998244353.	Hard8	ArraySegment tree+1	No attempts yet	2s	512 MB	Judgeable
NamuhsGiven N unknown planet potentials, find the unique contiguous segment with the maximum sum using only queries that compare the sums of two segments.	Hard8	Divide and conquerBinary search+2	No attempts yet	2s	512 MB	Judgeable
ResistancePlayers leave and return over time; after each change report the maximum value of a split into two teams, where friendship edges crossing the split are lost.	Hard8	GraphMinimum spanning tree+2	No attempts yet	2s	512 MB	Judgeable
Triple JumpFor each range [L, R], find the maximum A[a]+A[b]+A[c] over indices a<b<c inside the range where b-a <= c-b.	Hard8	Divide and conquerSegment tree+1	No attempts yet	2s	512 MB	Judgeable
ExamFor each of Q threshold triples, count students with S>=X, T>=Y, and S+T>=Z, where N and Q reach 100000.	Hard8	SortingPrefix sum+2	No attempts yet	3s	1024 MB	Judgeable
Two AntennasGiven antennas in a line, each with a height and a reach range, answer queries for the largest height difference among communicating pairs inside [L, R], or -1 if none exist.	Hard8	Segment treeStack+1	No attempts yet	3s	512 MB	Judgeable
Special Tourist CityGiven a tree whose edges each have two repair costs, find for each E the minimum personal-fund repair cost when E cities are made special.	Hard8	TreeDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Time-Traveling VitaroCities are joined in a line by roads that open only in given time windows; the task answers minimum time-rewind uses for trips while windows change.	Hard8	Segment treeIntervals+1	No attempts yet	3s	512 MB	Judgeable
Cake 3Choose M of N slices and arrange them in a cycle to maximize total value minus the sum of absolute color-depth differences around the cycle.	Hard8	Dynamic programmingGreedy+2	No attempts yet	4s	256 MB	Judgeable
MergeGiven a tree of N cities colored by K states, find the fewest state merges so that no split of the cities into two connected groups remains.	Hard8	TreeDFS+1	No attempts yet	3s	256 MB	Judgeable
MineralsGiven 2N slices forming N unknown pairs, determine all pairs using at most 1,000,000 device operations that report the number of distinct mineral kinds currently inserted.	Hard8	Divide and conquerImplementation+2	No attempts yet	1s	256 MB	Judgeable
Construction of HighwayEach construction adds a road from A to B and sets the 1-to-A path to B's liveliness. Report how many pairs on that path have a larger value before t.	Hard8	TreeSegment tree+1	No attempts yet	1s	256 MB	Judgeable
FencesGiven a square pasture and existing fence segments, find the minimum total length of new fences needed to fully enclose the pasture inside the lot.	Hard8	GeometryShortest path+1	No attempts yet	1s	256 MB	Judgeable
TentsCount nonempty subsets of tents on an H by W grid with directions obeying monotone entrance rules in every row and column, modulo 1e9+7.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Worst Reporter 3Given each contestant's slowness D_i, answer queries asking how many contestants stand in coordinate range [L, R] at time T.	Hard8	Segment treeSorting+1	No attempts yet	2s	256 MB	Judgeable
LibraryGiven a hidden permutation of N books, query the oracle with a set of book numbers and receive the minimum number of contiguous-block removals needed to extract exactly those books, then recover the order.	Hard8	IntervalsMath+2	No attempts yet	2s	512 MB	Judgeable
Wild BoarGiven a weighted road graph where the boar cannot U-turn, find the shortest walk that visits a supply plan in order after each point update, or -1 if no walk exists.	Hard8	GraphShortest path+2	No attempts yet	10s	1024 MB	Judgeable
CultivationGiven N grass cells on a huge R by C grid, find the fewest years needed to fill every cell when each year's wind blows in one of four directions.	Hard8	Binary searchGreedy+1	No attempts yet	2s	512 MB	Judgeable
Broken DeviceBuild a 150-bit sequence for a 64-bit integer X so the receiver can recover X even when up to 40 unknown positions are forced to 0.	Hard8	Bit manipulationMath+1	No attempts yet	2s	512 MB	Judgeable
Railway TripGiven station levels that define which train types stop where, answer each query with the fewest intermediate stops needed to travel between two stations.	Hard8	ArrayDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Dragon 2For each conflict, count the fireballs from tribe F's dragons toward tribe G's dragons whose half-lines cross the road between the two villages.	Hard8	GeometrySorting+1	No attempts yet	2s	512 MB	Judgeable
MatryoshkaFor each query (A, B), take the dolls with R >= A and H <= B and find the minimum number of chains needed to store them all nested, i.e. the size of the largest antichain under the containment partial order.	Hard8	SortingDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
TelegraphEach island's receiver points to one other island; turning it costs C_i. Find the minimum total cost so that every island can reach every other in the resulting functional graph.	Hard8	GraphGreedy+2	No attempts yet	1s	512 MB	Judgeable
Copy and Paste 2Simulate N copy-and-paste edits on a string capped at length M, tracking positions backward so the first K characters of the final string can be printed.	Hard8	ImplementationBinary search+2	No attempts yet	1s	512 MB	Judgeable
JOI Logo DesignGiven a circular string of length 4^K over {J,O,I}, find the rotation that minimizes mismatches with a level-K JOI sequence built by recursive quarter block replacement.	Hard8	Dynamic programmingDivide and conquer+2	No attempts yet	1s	512 MB	Judgeable
Growing Vegetables is Fun 2Choose which plants to pull up so that each remaining plant is the tallest on at least one side of it, maximizing fruit sales minus pulling costs.	Hard8	Dynamic programmingTree+1	No attempts yet	1s	512 MB	Judgeable
IOIOI CardsGiven a row of I/O cards and interval flip operations with per-length costs, decide whether all cards can be turned face up and find the minimum total flip time.	Hard8	Shortest pathGraph+2	No attempts yet	1s	512 MB	Judgeable
Building 3Given the sequence B with one entry deleted from A, where A_i is the longest increasing chain ending at building i, count how many full sequences A could produce B.	Hard8	Dynamic programmingArray+1	No attempts yet	1s	512 MB	Judgeable
InheritanceK children take turns picking the heaviest cycle-free set of edges from the graph, and we must report which child gets each edge or 0 if nobody does.	Hard8	GraphUnion-find+2	No attempts yet	1s	512 MB	Judgeable
WallsEach wall must cover every laser column P_j in attack order, and the task asks for the fewest unit moves needed per wall.	Hard8	Dynamic programmingGreedy	No attempts yet	3s	256 MB	Judgeable
BusGiven scheduled one-way buses with fixed departure and arrival times, compute for each query deadline L the latest time to leave stop 1 to reach stop N by L, or -1.	Hard8	GraphSorting+2	No attempts yet	1s	512 MB	Judgeable
Growing Vegetables is FunGiven N plants in a row, find the minimum adjacent swaps to arrange heights so every plant is a prefix maximum or a suffix maximum.	Hard8	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
Making Friends is FunGiven a directed graph of ambassador arrows, repeatedly pick a mediator x and two countries p,q with arrows (x,p) and (x,q), then add (p,q) and (q,p); maximize final arrow count.	Hard8	GraphUnion-find+2	No attempts yet	1s	512 MB	Judgeable
ScarecrowsCount pairs of scarecrows that can be the SW and NE corners of an axis-aligned rectangle whose interior contains no other scarecrow.	Hard8	SortingDivide and conquer+1	No attempts yet	4s	512 MB	Judgeable
Constellation 2Count unordered pairs of non-overlapping triangles, each with one red, one blue, and one yellow star, among N colored points.	Hard8	GeometrySorting+1	No attempts yet	9s	512 MB	Judgeable
Collecting Images is FunStart with an all-white 2^N by 2^N grid; after each of Q row or column flips, report the size of the quadtree that represents the image.	Hard8	Divide and conquerImplementation+2	No attempts yet	5s	256 MB	Judgeable
Communication JammingGiven two planar networks linking villages on the x-axis to hubs above and below, find for each A the largest B that keeps all villages connected after cutting hubs.	Hard8	Union-findGraph+2	No attempts yet	2s	256 MB	Judgeable
MascotsCount the orders of placing the remaining mascots so that the number of steps where the occupied cells form a full rectangle is maximized, modulo 1e9+7.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	2s	256 MB	Judgeable
SpyGiven a subordinate subtree for every leader in two rooted trees of N employees, count for each IOI employee how many of the M spy projects succeed, where spy b succeeds when the matching JOI employee lies in research project b's subtree.	Hard8	TreeDFS+2	No attempts yet	2s	256 MB	Judgeable
CakeOn a circular cake, JOI takes one piece, then the two players alternately take pieces next to taken ones, largest first. For each starting piece, find JOI's total size.	Hard8	GreedyUnion-find+1	No attempts yet	1.5s	256 MB	Judgeable
White Day Present ExchangeEach student gives treats to one other student; choose whether each makes cookies or cake to maximize total happiness from what they receive.	Hard8	GraphDynamic programming+2	No attempts yet	1s	256 MB	Judgeable
EquationCount integers n in [a, b] up to 10^18 with k times the sum of squares of n's decimal digits equal to n.	Hard8	MathBrute force+2	No attempts yet	2s	512 MB	Judgeable
ChampionshipsFind the largest set of vertices in an undirected graph that is connected and where every vertex has at least d neighbors inside the set.	Hard8	GraphImplementation+2	No attempts yet	2s	512 MB	Judgeable
Cell ExplosionGiven cell division rules and a target sequence S, find the first minute when S appears as a contiguous segment of the worm's cell sequence, or report -1.	Hard8	String matchingDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
RobotsFind a number of commands k so that every robot, whatever its nondeterministic moves, is in a base after k moves, or report -1 if none exists.	Hard8	MatrixBit manipulation+1	No attempts yet	10s	512 MB	Judgeable
GymGive each booking one hour inside its interval so that no machine is used twice in the same hour, minimizing the number of hours with someone in the gym.	Hard8	GreedySorting+2	No attempts yet	10s	512 MB	Judgeable
JOI FlagFill and fix a 2^K by 2^K grid so it follows the recursive quadrant rule for JOI flags, minimizing the number of already-written cells whose character must change.	Hard8	Divide and conquerDynamic programming+2	No attempts yet	3s	512 MB	Judgeable
Conveyor BeltsBuild a belt network of at most 200 fixed a:b splitters that divides one global input into c:d between the two outputs, given a, b, c, and d.	Hard8	MathNumber theory+1	No attempts yet	1s	512 MB	Judgeable
Inquiry IIGiven a connected simple graph with at most n+15 edges, output the size of its maximum independent set.	Hard8	TreeDFS+2	No attempts yet	5s	512 MB	Judgeable
Estate AgentGiven directed offers between families with amounts, pick a subset of disjoint cycles so the total sum of offer amounts is maximized, then output 5% of it.	Hard8	GraphDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Grand Central StationGiven a tree, find the minimum number of distinct map designs (rooted drawings) such that every vertex can be the center of one design after relabeling.	Hard8	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
Hat StandPlace c-1 spare hats on hooks so the total walking distance over a given sequence of n hats is minimized, then output the best arrangement.	Hard8	GreedyDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Mosaic MansionGiven n rows of m colored tiles, remove rows so that the kept rows contain the same number of tiles of each color; maximize the number of kept rows.	Hard8	Dynamic programmingHash map+2	No attempts yet	12s	512 MB	Judgeable
DžumbusGiven a forest of N friends with drink thresholds, and Q queries each supplying a total drink S, find the maximum number of people who exchange solutions.	Hard8	Dynamic programmingTree+2	No attempts yet	1s	512 MB	Judgeable
Sequence and Queries 33Given an array and range queries (l, r, k), find the maximum total sum of k non-overlapping non-empty subarrays inside A[l..r].	Hard8	Dynamic programmingSegment tree+1	No attempts yet	5s	512 MB	Judgeable
Dice YutnoriGiven 10 die rolls, move one of four pieces around a branching Yutnori board each turn and maximize the score collected from numbered squares.	Hard8	BacktrackingSimulation+2	No attempts yet	2s	512 MB	Judgeable
Lion and RabbitCount the ordered pairs of distinct vertices in a connected undirected graph for which the lion can never catch the rabbit under simultaneous blind moves.	Hard8	GraphBFS+2	No attempts yet	1s	256 MB	Judgeable
Fibonacci MusicBuild a digit string from Fibonacci numbers reduced mod M and answer queries for the N-th digit, with N up to 10^15.	Hard8	MathNumber theory+2	No attempts yet	1s	512 MB	Judgeable
Copy and PasteGiven a string of up to 200,000 lowercase letters, find the length of the longest substring that appears at least twice at disjoint positions, or -1 if none exists.	Hard8	StringBinary search+2	No attempts yet	2s	512 MB	Judgeable
Cheese, If You PleaseGiven limited pounds of n cheese types and m blends with fixed percentage recipes and per-pound profits, find the maximum achievable profit and round it to the nearest cent.	Hard8	MathGreedy+2	No attempts yet	2s	512 MB	Judgeable
Just Passing ThroughGrid path from the west edge to the east edge moving east, northeast, or southeast, crossing exactly n passes, minimizing total elevation.	Hard8	Dynamic programmingMatrix+2	No attempts yet	2s	512 MB	Judgeable
Where Have You Bin?Given a row of bins labeled by company, delete the listed bins, add the requested new bins, and find the minimum total item cost to keep every company's bins contiguous.	Hard8	Dynamic programmingImplementation+2	No attempts yet	1s	512 MB	Judgeable
Circle GardenGiven side lengths of a cyclic polygon, find the circumradius, or report no circle, an outside center, or a radius over 120 inches.	Hard8	GeometryMath+2	No attempts yet	1s	512 MB	Judgeable
Integers in Rational BasesGiven coprime p and q, write a positive integer n in the unique base p/q expansion whose digits are all at most p-1, printing digits 0-9, A-Z, a-z.	Hard8	Number theoryMath+2	No attempts yet	1s	512 MB	Judgeable
HogwartsGiven two edge-labelled 4-out graphs on n rooms, decide whether every instruction sequence that walks from room 1 to room n in the old graph also walks from 1 to n in the new graph.	Hard8	GraphBFS+2	No attempts yet	1s	512 MB	Judgeable
MoleculesGiven a connected graph with some vertex positions fixed, find positions for the rest so each unknown vertex sits at the average of its neighbors; any valid solution is accepted.	Hard8	GraphMath+2	No attempts yet	2s	512 MB	Judgeable
Watch LaterGiven a string of video types, find the minimum number of manual clicks needed to watch everything, where playback auto-advances to the next video only if it has the same type.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	6s	512 MB	Judgeable
Pairing SocksGiven a sequence of 2n socks, find the minimum number of moves to pair all socks using two stacks with three allowed operations, or report impossible.	Hard8	StackGreedy+2	No attempts yet	1s	512 MB	Judgeable
Tree HuggingGiven 2(n-1) edges on n points, decide whether they can be split into a left-rooted increasing tree and a right-rooted decreasing tree, and output one such labeling.	Hard8	GraphGreedy+2	No attempts yet	2s	512 MB	Judgeable
Loo RollsFind the smallest number of loo rolls, each of length l, so that consuming n per visit never triggers a shortage.	Hard8	MathNumber theory+2	No attempts yet	1s	512 MB	Judgeable
Type ChartsGiven observed results of type-1 attacks on single or double-typed Nudgémon, the task is to output a first row of the type chart that matches every observation.	Hard8	MathBit manipulation+1	No attempts yet	2s	512 MB	Judgeable
Dice and LaddersFind the minimum number of die rolls so that the probability of finishing a snakes-and-ladders board within that many rolls is at least p.	Hard8	ProbabilityDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Counting Permutations with a Given Greedily Increasing SubsequenceCount the permutations of 1 to N whose greedily increasing subsequence equals a given sequence G, modulo 1e9+7.	Hard8	CombinatoricsMath+2	No attempts yet	1s	512 MB	Judgeable
Train TicketsGiven yearly prices for 12 ticket lengths, find the cheapest set of tickets covering January of year a through December of year b for each query.	Hard8	Dynamic programmingDivide and conquer+1	No attempts yet	2s	512 MB	Judgeable
LoglandGiven coin counts for powers of two up to 2^(k-1), find the least total value that must be left behind so the rest splits into two equal halves, modulo 1e9+7.	Hard8	Bit manipulationGreedy+1	No attempts yet	1s	512 MB	Judgeable
Ranch CCTVFor each query, sheep in a grid shift one cell per day in a fixed direction for K days; report the XOR of the daily maximum over the CCTV rectangle.	Hard8	Prefix sumMatrix+2	No attempts yet	2s	256 MB	Judgeable