Problems

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Total results29,286 problems

Birthday
Hard8
Prefix sum, Stack+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
A+B
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Sorting Fractions
Hard8
Binary search, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Optical Communication Channels
Hard8
Tree, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Castle Defense
Hard8
Greedy, Binary search+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Dart
Hard8
Geometry, Binary search+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Leblanc's Tree Traversal
Hard8
Tree, DFS+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Forest Game
Hard8
Tree, Game theory+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Balanced Development
Hard8
Tree, Simulation+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Inventor Outlasting
Hard8
Game theory, Simulation+1
No attempts yet
Time limit
40s
Memory limit
1024 MB
Judgeable
Broken Device 2
Hard8
Math, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sprinkler
Hard8
Tree, DFS+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Fish 2
Hard8
Divide and conquer, Greedy+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Reconstruction Project
Hard8
Graph, Minimum spanning tree+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Reversible Compression
Hard8
Dynamic programming, String+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Planning Railroad Discontinuation
Hard8
Minimum spanning tree, Graph+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Genealogy of Puppets
Hard8
Dynamic programming, Tree+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
262144 Revisited
Hard8
Divide and conquer, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Hoof and Brain
Hard8
Graph, BFS
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Up Down Subsequence
Hard8
Dynamic programming, Segment tree+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Pair Programming
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Fields Division
Hard8
Graph, DFS+2
No attempts yet
Time limit
0.3s
Memory limit
1024 MB
Judgeable
Punch Through
Hard8
Dynamic programming, Segment tree+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Flappy Bird
Hard8
Segment tree, Dynamic programming+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Histogram
Hard8
Stack, Dynamic programming+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Colorful Bracket Sequences
Hard8
Dynamic programming, String
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Joyful KMP
Hard8
String matching, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Drone Photo
Hard8
Matrix, Sorting+1
No attempts yet
Time limit
2s
Memory limit
2048 MB
Judgeable
Gastronomic Event
Hard8
Tree, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
2048 MB
Judgeable
Celebration
Hard8
Graph, Topological sort+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Quantum Communication
Hard8
Hash map, Bit manipulation+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
The Locked Box
Hard8
Segment tree, Matrix+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Robot Game
Hard8
Bit manipulation, Dynamic programming+1
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Delicacy
Hard8
Matrix, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Destiny
Hard8
Tree, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Surreal
Hard8
Tree, Recursion+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Road
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
6s
Memory limit
1024 MB
Judgeable
Radar
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Repetitions
Hard8
String matching, Divide and conquer+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Systematic salesman
Hard8
Divide and conquer, Dynamic programming+1
No attempts yet
Time limit
6s
Memory limit
256 MB
Judgeable
Counting Rectangles
Hard8
Segment tree, Stack
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Strange Graph
Hard8
Minimum spanning tree, Union-find+1
No attempts yet
Time limit
7s
Memory limit
1024 MB
Judgeable
Integer Lines
Hard8
Geometry, Math+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Surrounded
Hard8
BFS, Graph+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Dawn Detective Game
Hard8
Game theory, BFS+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Cake Slices (Hard)
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Alternating Heights
Hard8
Graph, Topological sort+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Bi-ing Lottery Treekets
Hard8
Tree, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Triangular Logs
Hard8
Segment tree, Sorting+1
No attempts yet
Time limit
12s
Memory limit
1024 MB
Judgeable
Gahee and Sajik Stadium
Hard8
Graph, Brute force
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Joined Sessions
Hard8
Intervals, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Stranded Far From Home
Hard8
Graph, Union-find+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Permutation
Hard8
Greedy, Bit manipulation+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
The Great Egg Hunt
Hard8
Tree, Divide and conquer+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Oil-Producing Country
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
I Herd You Like Ternary Operators
Hard8
String, Stack+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Letter Delivery
Hard8
Greedy, Sorting+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Merge the Tree and Sequence
Hard8
Tree, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Dao and the Triple Mex Game
Hard8
Array, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Tree Cutting Game
Hard8
Tree, DFS+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
The Flower of the Game
Hard8
Tree, Dynamic programming+1
No attempts yet
Time limit
6s
Memory limit
1024 MB
Judgeable
Fancy Stack
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Job Lookup
Hard8
Dynamic programming, Tree+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Big City
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Sum of Subarray Sums Under Range Assignment Queries
Hard8
Segment tree, Combinatorics+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Semiconductor Fabrication
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Event Horizon
Hard8
Graph, Segment tree+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Numbers on a Board: Expected Sum and Product
Hard8
Combinatorics, Math
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Lagrange's Theorem Has Subtraction Too
Hard8
Number theory, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Outer Ring Road
Hard8
Shortest path, Tree+1
No attempts yet
Time limit
7s
Memory limit
1024 MB
Judgeable
Measures
Hard8
Binary search, Segment tree+2
No attempts yet
Time limit
1.5s
Memory limit
512 MB
Judgeable
Split into Intervals
Hard8
Dynamic programming, Array
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Catfish Farm
Hard8
Dynamic programming, Segment tree
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Prisoners' Challenge
Hard8
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Kingdom
Hard8
Dynamic programming, Binary search+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Tipover Transform
Hard8
Dynamic programming, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Merciless Shortest Path
Hard8
Shortest path, Graph+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Common Substring Queries
Hard8
String matching, Tree+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Lord of the Characteristic Polynomials (2)
Hard8
Matrix, Math+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
No More Headaches from Mental Math!
Hard8
Math, Number theory+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Parking
Hard8
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Keep in Touch
Hard8
Binary search, Geometry+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Make an X (Hard)
Hard8
Dynamic programming, Segment tree+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Strange Number 2
Hard8
Number theory, Math+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Yeoksam Station
Hard8
String, String matching+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Sorting Program
Hard8
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Cola Picking
Hard8
Dynamic programming, Matrix
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Suffix Sort
Hard8
String, String matching+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Counting Sequence
Hard8
Dynamic programming, Math+1
No attempts yet
Time limit
16s
Memory limit
1024 MB
Judgeable
Flower's Land
Hard8
Dynamic programming, Tree+1
No attempts yet
Time limit
8s
Memory limit
2048 MB
Judgeable
Just Another Number Theory Problem
Hard8
Number theory, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Walls and Wind
Hard8
Greedy, Sorting+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Matrix Multiplication Order 4
Hard8
Dynamic programming, Greedy
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Two-dimensional array
Hard8
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Maximum Frequency After One Subarray Add
Hard8
Array, Hash map+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Ramen
Hard8
Dynamic programming, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Rectangle Placement
Hard8
Combinatorics, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
X-Sums Sudoku
Hard8
Math, Bit manipulation+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Patrick's Parabox
Hard8
Simulation, BFS+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Hearthstone
Hard8
Greedy, Hash map+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
BirthdayGiven n double-sided cards, sum over all segments [l, r] the largest achievable total not divisible by k, modulo 1e9+7.	Hard8	Prefix sumStack+2	No attempts yet	2s	512 MB	Judgeable
A+BCount the column permutations of three n-digit rows that make a+b=c hold with no leading zeros, modulo 10^9+7.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	1s	512 MB	Judgeable
Sorting FractionsGiven two sets of distinct integers, sort all reduced fractions a_i/b_j and output the c-th fraction in the sorted list for each query.	Hard8	Binary searchSorting+2	No attempts yet	1s	512 MB	Judgeable
Optical Communication ChannelsGiven a rooted tree where each node has at most k chosen edges, pick the maximum number of edges forming a degree-bounded subgraph, and among those the minimum total weight.	Hard8	TreeDynamic programming+1	No attempts yet	1s	512 MB	Judgeable
Castle DefenseGiven enemy counts at each point on a line, choose archer count k and shot interval t so the castle takes under E damage, minimizing ak - bt.	Hard8	GreedyBinary search+1	No attempts yet	2s	1024 MB	Judgeable
DartGiven a convex polygon dartboard and two lists of dart throws, compute each player's total score modulo 1e9+7 and report the winner.	Hard8	GeometryBinary search+1	No attempts yet	2s	1024 MB	Judgeable
Leblanc's Tree TraversalGiven a tree, decide whether Leblanc can visit every edge exactly once from some start vertex, using moves along edges and two teleport checkpoints.	Hard8	TreeDFS+1	No attempts yet	2s	1024 MB	Judgeable
Forest GameCount the non-empty sets of trees where B wins the stone game, with each turn moving a stone 1 to K unused branches, modulo 998244353.	Hard8	TreeGame theory+2	No attempts yet	2s	1024 MB	Judgeable
Balanced DevelopmentGiven a weighted tree and an activation permutation, find when each region activates as ancestor population inflows trigger chain activations.	Hard8	TreeSimulation+2	No attempts yet	5s	512 MB	Judgeable
Inventor OutlastingTwo players take turns building attractions on free X cells, where each build fills diagonal sign runs; count the first moves that let the first player win.	Hard8	Game theorySimulation+1	No attempts yet	40s	1024 MB	Judgeable
Broken Device 2Anna must encode an integer up to 10^18 into 0/1 arrays sent through a riffle-shuffle device so Bruno can recover it exactly.	Hard8	MathBit manipulation+1	No attempts yet	2s	512 MB	Judgeable
SprinklerGiven a tree of lands with millet heights, multiply every height within distance D of a land by W modulo L, and answer height queries for single lands.	Hard8	TreeDFS+2	No attempts yet	4s	1024 MB	Judgeable
Fish 2With point updates to fish sizes, count how many fish in range [L, R] could be the one that eats all the others when the fish are merged left to right.	Hard8	Divide and conquerGreedy+1	No attempts yet	4s	1024 MB	Judgeable
Reconstruction ProjectGiven a connected graph with edge widths, find for each query X the minimum total width change so that a spanning tree has every edge equal to X.	Hard8	GraphMinimum spanning tree+1	No attempts yet	5s	1024 MB	Judgeable
Reversible CompressionFind the shortest code string whose decoding matches the given digits and still matches when the code is reversed. Ties go to the lexicographically smallest.	Hard8	Dynamic programmingString+1	No attempts yet	2s	1024 MB	Judgeable
Planning Railroad DiscontinuationGiven l copies of a subway network arranged in a ring and linked by bullet trains at fixed stations, find the minimum total cost of routes that keeps every station connected.	Hard8	Minimum spanning treeGraph+1	No attempts yet	5s	1024 MB	Judgeable
Genealogy of PuppetsCount the ordered binary trees on n puppets that respect each puppet's child-count limits and require a later-released child under every parent with children, modulo 1e9+7.	Hard8	Dynamic programmingTree+1	No attempts yet	2s	1024 MB	Judgeable
262144 RevisitedMerge adjacent pairs into one more than the larger value, and sum the minimum final number over every contiguous subarray.	Hard8	Divide and conquerDynamic programming+1	No attempts yet	2s	1024 MB	Judgeable
Hoof and BrainGiven a directed graph and two starting tokens, decide for each query whether the brain or the hoof wins the token-moving game.	Hard8	GraphBFS	No attempts yet	4s	1024 MB	Judgeable
Up Down SubsequenceGiven a permutation and a string of U and D letters, find the longest subsequence whose consecutive comparisons match the letters.	Hard8	Dynamic programmingSegment tree+1	No attempts yet	2s	1024 MB	Judgeable
Pair ProgrammingCount the distinct expressions formed by interleaving two programs of N instructions each, modulo 10^9+7.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	2s	1024 MB	Judgeable
Fields DivisionSplit a connected graph of N fields into two connected parts so that the wheat sums (field i yields 2i kg) are as close as possible.	Hard8	GraphDFS+2	No attempts yet	0.3s	1024 MB	Judgeable
Punch ThroughGiven N membranes in an N by M tunnel, find the minimum cost to pass through when teleporting costs A and passing a membrane costs B, for many (A, B) queries.	Hard8	Dynamic programmingSegment tree+1	No attempts yet	5s	1024 MB	Judgeable
Flappy BirdFind the maximum total weight of axis-parallel segments Anna can touch on a rightward flight that changes height once inside the box 0 to W by 0 to H.	Hard8	Segment treeDynamic programming+1	No attempts yet	4s	1024 MB	Judgeable
HistogramGiven a histogram of N bars, find the maximum total area of at most K non-overlapping rectangles for K = 1, 2, and 3.	Hard8	StackDynamic programming+1	No attempts yet	4s	1024 MB	Judgeable
Colorful Bracket SequencesCount the distinct colorful bracket subsequences of a colored bracket string, where adjacent and matched brackets must have different colors.	Hard8	Dynamic programmingString	No attempts yet	2s	1024 MB	Judgeable
Joyful KMPCount the lowercase strings that have the same failure function as the given string, and print the K-th one in lexicographic order or OVER.	Hard8	String matchingCombinatorics+1	No attempts yet	1s	1024 MB	Judgeable
Drone PhotoCount the axis-aligned rectangles of contestants where the two youngest corners form one pair of opposite sides and the two oldest form the other pair.	Hard8	MatrixSorting+1	No attempts yet	2s	2048 MB	Judgeable
Gastronomic EventAssign ratings 1 to n to the rooms of a tree so that the number of edge-following paths with increasing ratings is maximized, and print that maximum.	Hard8	TreeDynamic programming+1	No attempts yet	2s	2048 MB	Judgeable
CelebrationFor each parade, count the cities that can lie on some path from s to t after adding up to two temporary one-way roads.	Hard8	GraphTopological sort+1	No attempts yet	2s	1024 MB	Judgeable
Quantum CommunicationFor each online query, decide whether a 256-bit string lies within Hamming distance k (at most 15) of some word in a dictionary of up to 400,000 words.	Hard8	Hash mapBit manipulation+1	No attempts yet	3s	1024 MB	Judgeable
The Locked BoxMaintain the value of a continued fraction built from a W/E operation string under append, flip, and reverse updates, printing it modulo 998244353.	Hard8	Segment treeMatrix+1	No attempts yet	3s	1024 MB	Judgeable
Robot GameCount the input and output tape combinations for which some start square lets every robot finish its operations without exploding and produce its target tape.	Hard8	Bit manipulationDynamic programming+1	No attempts yet	10s	1024 MB	Judgeable
DelicacyFind the maximum happiness from a trip that starts and ends in city 1 on day T, where each city visit adds its value and timed festivals add bonuses, or report -1.	Hard8	MatrixDynamic programming+1	No attempts yet	2s	1024 MB	Judgeable
DestinyCount the 0/1 labelings of tree edges so that every ancestor-descendant pair in Q has at least one edge set to 1 on its path, modulo 998244353.	Hard8	TreeDynamic programming+1	No attempts yet	2s	1024 MB	Judgeable
SurrealGiven a finite set of rooted binary trees, decide whether only finitely many trees cannot be reached from them by repeatedly replacing leaves with trees.	Hard8	TreeRecursion+1	No attempts yet	1s	1024 MB	Judgeable
RoadFind the minimum total length of a route from city s to city t whose roads can be removed while the remaining roads still connect all cities.	Hard8	GraphShortest path+1	No attempts yet	6s	1024 MB	Judgeable
RadarEach radius and ray direction gives one scanned point. For each query point, output the distance to the nearest scanned point.	Hard8	GeometrySorting+1	No attempts yet	2s	256 MB	Judgeable
RepetitionsGiven a lowercase string of up to 10^6 letters and up to 100 range queries, find the longest square tt inside each range and its leftmost start.	Hard8	String matchingDivide and conquer+1	No attempts yet	10s	512 MB	Judgeable
Systematic salesmanFind the shortest path through all cities when the route must alternate left/right and lower/upper splits of the point set, and print the visiting order.	Hard8	Divide and conquerDynamic programming+1	No attempts yet	6s	256 MB	Judgeable
Counting RectanglesArrays A and B grow by appends, and after some appends the task asks for the number of all-black subrectangles of the grid where A_i + B_j is at least 0, modulo 998244353.	Hard8	Segment treeStack	No attempts yet	5s	1024 MB	Judgeable
Strange GraphGiven a complete graph whose edge weights come from entries of a matrix, find the total weight of its minimum spanning forest after removing M specified edges.	Hard8	Minimum spanning treeUnion-find+1	No attempts yet	7s	1024 MB	Judgeable
Integer LinesCount integer lines y = ax + b that split the n peppers into two equal groups without touching any pepper, or print -1 if there are infinitely many.	Hard8	GeometryMath+1	No attempts yet	5s	1024 MB	Judgeable
SurroundedMirko moves his piece on a grid to wall in Slavko's hidden piece before it reaches the border, and the task asks for the fewest wall cells needed.	Hard8	BFSGraph+1	No attempts yet	1s	1024 MB	Judgeable
Dawn Detective GameOn a grid with walls, the detective and thief move in turns, and the task is to find the fewest moves for the detective to lock the thief in prison, or print -1.	Hard8	Game theoryBFS+1	No attempts yet	1s	1024 MB	Judgeable
Cake Slices (Hard)Count the subsets of cake slices, where slice i is 1/c_i of a cake, whose total falls between 0.99 and 1.01 of a whole cake, modulo 10^9+7.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	3s	1024 MB	Judgeable
Alternating HeightsFor each query range, decide whether distinct heights can make the photo order alternate up and down, meaning the required comparisons contain no cycle.	Hard8	GraphTopological sort+1	No attempts yet	2s	1024 MB	Judgeable
Bi-ing Lottery TreeketsCount the distinct winning tickets produced by dropping K numbered balls into a rooted binary tree of N nodes, modulo 1e9+7.	Hard8	TreeDynamic programming+1	No attempts yet	1s	1024 MB	Judgeable
Triangular LogsFor each rectangle query, decide whether three trees inside it have heights that form a non-degenerate triangle.	Hard8	Segment treeSorting+1	No attempts yet	12s	1024 MB	Judgeable
Gahee and Sajik StadiumPlace N idols on an R by C grid to maximize total charm, counting each cell's charm and the extra charm for adjacent Three Musketeers pairs.	Hard8	GraphBrute force	No attempts yet	1s	512 MB	Judgeable
Joined SessionsGiven n intervals, find the fewest merges of overlapping intervals that lower the minimum number of intervals needed to overlap every other interval, or report impossible.	Hard8	IntervalsGreedy+1	No attempts yet	2s	1024 MB	Judgeable
Stranded Far From HomeGiven village populations and a road map, find every village whose initial tie color could become the final color for all islanders.	Hard8	GraphUnion-find+2	No attempts yet	1s	512 MB	Judgeable
PermutationFor each query k, build a permutation of 0 to n-1 with a small n whose increasing subsequences, including the empty one, number exactly k.	Hard8	GreedyBit manipulation+1	No attempts yet	1s	256 MB	Judgeable
The Great Egg HuntGiven a tree of N rooms, find all starting rooms that minimize the expected time for Egg First Search to find the hidden egg.	Hard8	TreeDivide and conquer+1	No attempts yet	3s	1024 MB	Judgeable
Oil-Producing CountryGiven a tree with N nodes plus M extra edges, pick two edges to toll so the total toll collected over all shortest paths between node pairs is maximized.	Hard8	GraphShortest path+2	No attempts yet	2s	1024 MB	Judgeable
I Herd You Like Ternary OperatorsCount the distinct parse trees of a parenthesis-free ternary expression made of letters, ? and :, modulo 1,000,000,007.	Hard8	StringStack+1	No attempts yet	1s	1024 MB	Judgeable
Letter DeliveryAssign letter requests to couriers on a line so the total round-trip distance is minimized, then print each courier's delivery order.	Hard8	GreedySorting+1	No attempts yet	3s	1024 MB	Judgeable
Merge the Tree and SequenceAssign the sequence B to the tree vertices one-to-one to find the minimum and maximum of the sum over color regions of (sum of A) times (sum of matched B).	Hard8	TreeSorting+1	No attempts yet	2s	1024 MB	Judgeable
Dao and the Triple Mex GameGiven array A, pick subsequences to build array B of mex values, then pick subarrays of B to build C. Find the maximum possible sum of C.	Hard8	ArrayGreedy+1	No attempts yet	1s	1024 MB	Judgeable
Tree Cutting GameGiven a tree with 2^K-1 vertices, find the maximum of (vertices minus edges) GS can reach by removing vertices and re-joining components.	Hard8	TreeDFS+1	No attempts yet	1s	1024 MB	Judgeable
The Flower of the GameGiven a weighted tree, find the longest path whose vertex weights strictly increase, and report that length again after each weight update query.	Hard8	TreeDynamic programming+1	No attempts yet	6s	1024 MB	Judgeable
Fancy StackCount the stacks that use all n blocks in a zigzag order where even positions strictly increase, modulo 998244353.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	3s	512 MB	Judgeable
Job LookupGiven a symmetric communication matrix, build a binary search tree on keys 1 to n that minimizes the total weighted distance between all pairs and print each node's parent.	Hard8	Dynamic programmingTree+1	No attempts yet	3s	512 MB	Judgeable
Big CityGiven N vertical and M horizontal roads with K officers on some of them, sum the minimum total movement for every pair of officers to meet.	Hard8	GraphShortest path+1	No attempts yet	3s	1024 MB	Judgeable
Sum of Subarray Sums Under Range Assignment QueriesGiven N cells and Q range-assign queries, sum every subarray sum over all query windows [U, D], modulo 998244353.	Hard8	Segment treeCombinatorics+1	No attempts yet	4s	1024 MB	Judgeable
Semiconductor FabricationChoose vertex potentials and edge energies, with E1=1.0 and EN=-1.0 fixed, to minimize total transfer cost, or print HAPPY if the cost can drop below zero.	Hard8	GraphShortest path+1	No attempts yet	4s	1024 MB	Judgeable
Event HorizonEach day every cell takes the maximum over a range of cells, and the task is to find the value each cell shows forever after.	Hard8	GraphSegment tree+1	No attempts yet	3s	1024 MB	Judgeable
Numbers on a Board: Expected Sum and ProductGiven N integers, find for each k the expected final sum after k product merges and the expected final product after k sum merges, modulo 998244353.	Hard8	CombinatoricsMath	No attempts yet	4s	1024 MB	Judgeable
Lagrange's Theorem Has Subtraction TooGiven an integer N with \|N\| up to 10^12, find the fewest distinct positive squares whose signed sum equals N and print each signed term.	Hard8	Number theoryMath+1	No attempts yet	1s	512 MB	Judgeable
Outer Ring RoadGiven a weighted tree whose leaves form a ring road, answer Q queries for the shortest travel time between two intersections.	Hard8	Shortest pathTree+1	No attempts yet	7s	1024 MB	Judgeable
MeasuresGiven N people on a line, find the minimum time for them to spread out so every pair is at least D apart, after each of M added people.	Hard8	Binary searchSegment tree+2	No attempts yet	1.5s	512 MB	Judgeable
Split into IntervalsChoose exactly K non-overlapping contiguous intervals to maximize the sum of (max minus min) over each interval, for every K from 1 to R.	Hard8	Dynamic programmingArray	No attempts yet	1s	1024 MB	Judgeable
Catfish FarmChoose a fishing spot length for each column of an N by N grid to maximize the total weight of the catfish that can be caught.	Hard8	Dynamic programmingSegment tree	No attempts yet	1s	1024 MB	Judgeable
Prisoners' ChallengeDesign a prisoner strategy that uses one blackboard integer to pass information, so the group can find the bag with fewer coins when each bag holds at most N coins.	Hard8	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
KingdomChoose K castles, including both endpoints on the x-axis, to maximize the area of their convex hull.	Hard8	Dynamic programmingBinary search+1	No attempts yet	1s	1024 MB	Judgeable
Tipover TransformGiven a row of cells with standing blocks of various heights, find the fewest 1 cm cube blocks needed so the hero can walk from cell 0 to cell N.	Hard8	Dynamic programmingGreedy+1	No attempts yet	1s	1024 MB	Judgeable
Merciless Shortest PathFind the shortest path length from village 1 to every village, where roads are implicit from coordinate gaps and z-sums divisible by K.	Hard8	Shortest pathGraph+1	No attempts yet	2s	1024 MB	Judgeable
Common Substring QueriesGiven N strings with total length up to 200,000, answer Q queries, each asking how many distinct substrings strings S_i and S_j share.	Hard8	String matchingTree+1	No attempts yet	4s	1024 MB	Judgeable
Lord of the Characteristic Polynomials (2)Given an n by n matrix whose entries are a + bsqrt(D), find each coefficient of its characteristic polynomial as p + qsqrt(D), reduced modulo M.	Hard8	MatrixMath+1	No attempts yet	5s	1024 MB	Judgeable
No More Headaches from Mental Math!Given N and M called numbers (duplicates allowed, N up to 1e9), find the product of the uncalled integers from 1 to N modulo 1e9+7.	Hard8	MathNumber theory+1	No attempts yet	2s	512 MB	Judgeable
ParkingOn a grid with fixed fountains, mark the most free cells as parking so each spot reaches the top-left exit without being blocked by other spots.	Hard8	Dynamic programmingBit manipulation+1	No attempts yet	3s	1024 MB	Judgeable
Keep in TouchGiven two polylines, find the minimum distance d such that agents A and B can walk their routes together while never being farther apart than d.	Hard8	Binary searchGeometry+1	No attempts yet	1s	1024 MB	Judgeable
Make an X (Hard)Given N pushpins, remove the fewest so the rest form an X around one center point, or print -1 if no X is possible.	Hard8	Dynamic programmingSegment tree+1	No attempts yet	1s	1024 MB	Judgeable
Strange Number 2Given N up to 1e9, sum f(A,B) over all pairs 1 to N, where f counts C whose GCD with A and LCM with B match the stated values.	Hard8	Number theoryMath+1	No attempts yet	2s	1024 MB	Judgeable
Yeoksam StationCount the distinct substrings of S that contain a palindrome of length at least K.	Hard8	StringString matching+1	No attempts yet	2s	1024 MB	Judgeable
Sorting ProgramCount the input sequences of N integers in [1, M] that a given list of conditional swaps sorts into ascending order, modulo 998244353.	Hard8	Dynamic programmingBit manipulation+1	No attempts yet	2s	1024 MB	Judgeable
Cola PickingFind the maximum total cola two shortest paths can collect when they share no cells except the two houses at (1,1) and (N,N).	Hard8	Dynamic programmingMatrix	No attempts yet	3s	1024 MB	Judgeable
Suffix SortSort all suffixes of a lowercase string by their minimal representation, where each new letter is renamed to the next unused letter in order, and print the start indices.	Hard8	StringString matching+1	No attempts yet	4s	1024 MB	Judgeable
Counting SequenceCount sequences of positive integers with adjacent differences of 1 and sum n, weighting each by c raised to the number of descents, modulo 998244353.	Hard8	Dynamic programmingMath+1	No attempts yet	16s	1024 MB	Judgeable
Flower's LandFor each city z, find the largest flower total over a connected set of exactly k cities that includes z, where z is the root of the tree.	Hard8	Dynamic programmingTree+1	No attempts yet	8s	2048 MB	Judgeable
Just Another Number Theory ProblemGiven n primes below 10^18 with the smallest under 100, sum the squared gaps between consecutive numbers in [0, product] divisible by at least one prime, modulo 998244353.	Hard8	Number theoryMath+1	No attempts yet	1s	1024 MB	Judgeable
Walls and WindFor each day, find the largest wind strength v that no wall collapses under when the walls are ordered optimally, printed as an irreducible fraction.	Hard8	GreedySorting+1	No attempts yet	3s	1024 MB	Judgeable
Matrix Multiplication Order 4Given N matrices whose row and column counts never increase, find the fewest multiplications needed to multiply them in their fixed order, with N up to 1,000,000.	Hard8	Dynamic programmingGreedy	No attempts yet	1s	512 MB	Judgeable
Two-dimensional arrayPlace 1 to N^2 in an N by N grid so that the smallest ratio p/q between two values sharing a row or column is as large as possible.	Hard8	MathImplementation	No attempts yet	1s	512 MB	Judgeable
Maximum Frequency After One Subarray AddGiven an array, add a constant to one subarray at most once to maximize how often a single value appears, then list every value that reaches that maximum.	Hard8	ArrayHash map+2	No attempts yet	3s	1024 MB	Judgeable
RamenGiven N noodle parts with signed deliciousness values, decide whether repeated prefix folds can shrink the noodle to length 1.	Hard8	Dynamic programmingGreedy+1	No attempts yet	1s	1024 MB	Judgeable
Rectangle PlacementCount the ways to draw two rectangles on a grid of W vertical and H horizontal lines so that their boundaries share no point, modulo 998244353.	Hard8	CombinatoricsMath+1	No attempts yet	1s	1024 MB	Judgeable
X-Sums SudokuGiven n, m, a direction, and an index, find the X-sum of that row or column in the lexicographically smallest 2^n by 2^m sudoku.	Hard8	MathBit manipulation+1	No attempts yet	4s	1024 MB	Judgeable
Patrick's ParaboxGiven a grid where the grid itself is the only box, find the minimum number of pushes to move the box to its target and the player to its target.	Hard8	SimulationBFS+1	No attempts yet	4s	1024 MB	Judgeable
HearthstoneAfter each event is appended to a growing sequence, report how many secrets must be in the hero zone and how many must be absent, or bug if the sequence becomes invalid.	Hard8	GreedyHash map+1	No attempts yet	2s	1024 MB	Judgeable