Problems

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Total results29,304 problems

John's Gift
Hard8
Sorting, Binary search+1
No attempts yet
Time limit
1.2s
Memory limit
1024 MB
Judgeable
Security System
Hard8
Geometry, Greedy+1
No attempts yet
Time limit
0.8s
Memory limit
1024 MB
Judgeable
Rainy Day
Hard8
Minimum spanning tree, Graph+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Distance in Crosses
Hard8
Math, Geometry+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Galactic Governments
Hard8
Backtracking, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Multiplication
Hard8
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Package
Hard8
Graph, Two pointers+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Vasya's graph
Hard8
Union-find, Graph+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Structure Alignment
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Maximum Coefficient of a Key Road
Hard8
Graph, Minimum spanning tree+2
No attempts yet
Time limit
8s
Memory limit
256 MB
Judgeable
Magical Maze
Hard8
Graph, Dynamic programming+1
No attempts yet
Time limit
1.5s
Memory limit
512 MB
Judgeable
Error in code
Hard8
Shortest path, Graph+2
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Level check
Hard8
Graph, BFS+2
No attempts yet
Time limit
4s
Memory limit
256 MB
Judgeable
Intersection Graph
Hard8
Geometry, Implementation+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
What a Horrible and Dreadful Formula
Hard8
String, Implementation+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Gifts from Santa
Hard8
Dynamic programming, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Color Numbers
Hard8
Bit manipulation, Dynamic programming
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Tower Defense
Hard8
Tree, Divide and conquer+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
String Product
Hard8
String, Math+2
No attempts yet
Time limit
4s
Memory limit
256 MB
Judgeable
Fence
Hard8
Probability, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Cubic Path
Hard8
Graph, Backtracking+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Algorithm Was Applied
Hard8
Graph, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Balanced Rainbow Sequence
Hard8
Dynamic programming, String+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Doesn't Contain Loops or Multiple Edges
Hard8
Graph, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Equal Adjacent Elements
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Formally, You Choose Three Integers
Hard8
Math, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hypercube
Hard8
Bit manipulation, Tree+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Suspects
Hard8
Intervals, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Array
Hard8
Array, Hash map+2
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Edges Counting
Hard8
Combinatorics, Math+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Equanimous
Hard8
Dynamic programming, Math
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Square Graph
Hard8
String matching, Union-find+2
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Three Dimensions
Hard8
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Cyclic Shift and Minimal Inversions
Hard8
Array, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Filipp Rukhovich
Hard8
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Minimum Spanning Tree of a Grid Graph
Hard8
Minimum spanning tree, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Mikhail Tikhomirov
Hard8
Intervals, Divide and conquer+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Yum Yum
Hard8
Graph, BFS+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Tree Transformation Puzzle
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Time is Money
Hard8
Shortest path, Graph+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Two Dots
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Vertex Merge Game
Hard8
Graph, Greedy+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Rock Paper Scissors Strategy
Hard8
Implementation, Brute force+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Polygon Area
Hard8
Geometry, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Dyson Circle
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Flatland Olympics
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
IXth Problem
Hard8
Greedy, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Burizon Fort
Hard8
Number theory, Math+2
No attempts yet
Time limit
1.4s
Memory limit
1024 MB
Judgeable
Screamers in the Storm
Hard8
Dynamic programming, Math+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Win Diesel
Hard8
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Finding the K-th Tasty Food 2
Hard8
Binary search, Divide and conquer+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Valid Parenthesis String
Hard8
Segment tree, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Leaf Matching
Hard8
Tree, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Two-Step Shortest Path 3
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
6s
Memory limit
1024 MB
Judgeable
Territory Grab
Hard8
BFS, Simulation+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Sequence (Hard)
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Jegi Kicking
Hard8
Binary search, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
F1ow3rC0n
Hard8
Segment tree, Array+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
A Certain Milk Delivery List (Hard)
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Wombats
Hard8
Dynamic programming, Divide and conquer+1
No attempts yet
Time limit
20s
Memory limit
256 MB
Judgeable
Bazza and Shazza
Hard8
Segment tree, Dynamic programming+2
No attempts yet
Time limit
13s
Memory limit
230 MB
Judgeable
Optimal Truck
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Bookshelf Sorting
Hard8
Array, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Garbage Robot
Hard8
Simulation, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tickets
Hard8
Shortest path, Segment tree+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
HILO
Hard8
Combinatorics, Math+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
HILO
Hard8
Simulation, Implementation+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Closest Cow Wins
Hard8
Dynamic programming, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Composite Function and Queries 2
Hard8
Graph, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Locked Doors
Hard8
Tree, Divide and conquer+2
No attempts yet
Time limit
40s
Memory limit
1024 MB
Judgeable
Painters' Duel
Hard8
Game theory, Graph+1
No attempts yet
Time limit
40s
Memory limit
1024 MB
Judgeable
Diverse Subarray
Hard8
Divide and conquer, Array+2
No attempts yet
Time limit
30s
Memory limit
1024 MB
Judgeable
Scrambled Words
Hard8
String matching, Hash map+2
No attempts yet
Time limit
Not set
Memory limit
1024 MB
Judgeable
Kickstart Alarm
Hard8
Math, Combinatorics+2
No attempts yet
Time limit
90s
Memory limit
1024 MB
Judgeable
Candies
Hard8
Array, Prefix sum+2
No attempts yet
Time limit
40s
Memory limit
1024 MB
Judgeable
Paragliding
Hard8
Dynamic programming, Geometry
No attempts yet
Time limit
40s
Memory limit
1024 MB
Judgeable
Funniest Word Search
Hard8
String matching, Trie+2
No attempts yet
Time limit
240s
Memory limit
1024 MB
Judgeable
Junghoon Wants to Eat Mint Chocolate Jajang Ramen
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Specializing Villages
Hard8
Graph, Minimum spanning tree+2
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Combining Classes
Hard8
Binary search, Prefix sum+2
No attempts yet
Time limit
180s
Memory limit
1024 MB
Judgeable
Let Me Count The Ways
Hard8
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
40s
Memory limit
1024 MB
Judgeable
Two Cubes
Hard8
Binary search, Geometry+1
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Tricky Trios
Hard8
Probability, Greedy+1
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Seating Chart
Hard8
Combinatorics, Math+2
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Three-Color Graph
Hard8
Binary search, Shortest path+2
No attempts yet
Time limit
7s
Memory limit
1024 MB
Judgeable
Funnels and Beakers
Hard8
Segment tree, Intervals+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Introductions Organization
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
40s
Memory limit
1024 MB
Judgeable
Theater Seat Assignment
Hard8
Greedy, Binary search+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Algorithm Class - Bubble Sort 6
Hard8
Sorting, Simulation+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
XCopy
Hard8
Bit manipulation, Matrix+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Dungeons
Hard8
Bit manipulation, Graph+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Joitter
Hard8
Graph, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Keycards
Hard8
Combinatorics, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Report
Hard8
Graph, DFS+2
No attempts yet
Time limit
0.5s
Memory limit
1024 MB
Judgeable
UFO Airport (UFO) 3
Hard8
Backtracking, Brute force+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
UFO Landing Field (UFO) 5
Hard8
Brute force, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Orienteering
Hard8
Dynamic programming, Graph+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sengoku
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
0.75s
Memory limit
1024 MB
Judgeable
Regions
Hard8
Binary search, Tree+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Finals Venue (Finals)
Hard8
Graph, Minimum spanning tree+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
John's GiftChoose the good to remove so the remaining goods match n-1 price tags with the smallest possible maximum absolute value-price difference, and print the smallest tied value.	Hard8	SortingBinary search+1	No attempts yet	1.2s	1024 MB	Judgeable
Security SystemFind the minimum number of non-touching horizontal or vertical tracks that let sensors watch every point of an x-monotone rectilinear polygon.	Hard8	GeometryGreedy+1	No attempts yet	0.8s	1024 MB	Judgeable
Rainy DayBuild skybridges so every building is reachable, where building i with degree k costs a_i*k^2, and minimize total cost.	Hard8	Minimum spanning treeGraph+2	No attempts yet	1s	1024 MB	Judgeable
Distance in CrossesSquares are tiled by crosses whose centers form a lattice; moving to a different cross costs one coin, and we must find the minimum coins between two given squares.	Hard8	MathGeometry+2	No attempts yet	2s	512 MB	Judgeable
Galactic GovernmentsGiven up to 18 axis-aligned boxes in k up to 10 dimensions, find a half-integer lattice point not covered by any box, choosing the lexicographically smallest.	Hard8	BacktrackingBrute force+2	No attempts yet	2s	512 MB	Judgeable
MultiplicationGiven an even n, output n distinct numbers so that after multiplying by a secret odd x mod 2^31, the judge returns half of the products, and you must recover x.	Hard8	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
PackageChoose one version per application so that no conflict contains two chosen packages; conflicts are disjoint package sets, so model each application as a vertex in a graph where a conflict forces a specific version.	Hard8	GraphTwo pointers+1	No attempts yet	2s	256 MB	Judgeable
Vasya's graphGiven K forbidden node pairs and M edges offered in order, keep each edge only if it does not connect any forbidden pair, and report which edges are kept.	Hard8	Union-findGraph+2	No attempts yet	2s	256 MB	Judgeable
Structure AlignmentParse a C struct declaration and, over all field orders, report the minimum, maximum, and average aligned memory size.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	2s	256 MB	Judgeable
Maximum Coefficient of a Key RoadFor each edge, find the largest value its weight can take while still belonging to some minimum spanning tree of the graph.	Hard8	GraphMinimum spanning tree+2	No attempts yet	8s	256 MB	Judgeable
Magical MazeCount ordered pairs of chambers (x, y) that both lie on some path from the entrance to the exit of a one-way grid maze, where y is reachable from x.	Hard8	GraphDynamic programming+1	No attempts yet	1.5s	512 MB	Judgeable
Error in codeGiven the output of a buggy Floyd-Warshall variant that only loops w, u, v up to N-1, recover the true all-pairs shortest path matrix.	Hard8	Shortest pathGraph+2	No attempts yet	5s	256 MB	Judgeable
Level checkGiven a fixed passable-cell map, decide for each layout whether the player can always reach a weapon before any monster, considering adversarial monster movement.	Hard8	GraphBFS+2	No attempts yet	4s	256 MB	Judgeable
Intersection GraphFor two axis-aligned boxes, list every nonempty boundary intersection as a point, curve, or surface and output its endpoints and incidences.	Hard8	GeometryImplementation+1	No attempts yet	1s	256 MB	Judgeable
What a Horrible and Dreadful FormulaGiven a string where digits were replaced by English number words, recover the original arithmetic expression or report that none exists, then evaluate it left to right.	Hard8	StringImplementation+2	No attempts yet	1s	256 MB	Judgeable
Gifts from SantaPartition a prefix of the gift sequence into K consecutive nonempty blocks, each child getting one block, minimizing the sum over blocks of (block sum minus the smallest block sum).	Hard8	Dynamic programmingPrefix sum+2	No attempts yet	1s	512 MB	Judgeable
Color NumbersFind the fewest colors for an array so that no pair, where one value is a bitwise submask of the other and their XOR has at least k set bits, shares a color.	Hard8	Bit manipulationDynamic programming	No attempts yet	1s	512 MB	Judgeable
Tower DefensePick a city in a tree so every tower covers it, where raising a tower's radius by x costs ceil(x/k), minimizing the total cost.	Hard8	TreeDivide and conquer+1	No attempts yet	5s	1024 MB	Judgeable
String ProductGiven a string s, find strings a and b with a times b equal to s (letters add mod 26), minimizing a+b lexicographically, then minimizing \|a\|.	Hard8	StringMath+2	No attempts yet	4s	256 MB	Judgeable
FenceEach segment is toggled independently with a given probability; find the expected total length of green points on the line.	Hard8	ProbabilityPrefix sum+2	No attempts yet	1s	256 MB	Judgeable
Cubic PathGiven n, find the longest path in the n-dimensional hypercube such that no shorter path between its endpoints uses only the points of that path.	Hard8	GraphBacktracking+1	No attempts yet	2s	256 MB	Judgeable
Algorithm Was AppliedGiven a connected graph, add edge b-c for each triple a<b<c where a-b and a-c are edges but b-c is not, then count n-color proper colorings of the final graph.	Hard8	GraphCombinatorics+1	No attempts yet	2s	512 MB	Judgeable
Balanced Rainbow SequenceFlip the fewest brackets so that the sequence stays balanced after removing all lime brackets and after removing all gray brackets.	Hard8	Dynamic programmingString+1	No attempts yet	2s	512 MB	Judgeable
Doesn't Contain Loops or Multiple EdgesGiven a properly k-colored graph and its coloring a, decide whether some other proper k-coloring b exists that is pointwise >= a everywhere or <= a everywhere.	Hard8	GraphGreedy+2	No attempts yet	2s	512 MB	Judgeable
Equal Adjacent ElementsCount orders to remove elements of an array with no equal neighbors so that this stays true after every removal, modulo 998244353.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	2s	512 MB	Judgeable
Formally, You Choose Three IntegersDecide whether array a can be turned into array b by repeatedly cyclically shifting an even-length contiguous block by an even number of positions.	Hard8	MathArray+2	No attempts yet	2s	512 MB	Judgeable
HypercubeGiven a tree with n edges, place the maximum number of edge-disjoint copies in the n-dimensional hypercube and output every placement.	Hard8	Bit manipulationTree+2	No attempts yet	1s	512 MB	Judgeable
SuspectsEach suspect has a height interval; a lineup is a contiguous range whose intervals admit distinct reals. For each query range [p,q], report the minimum number of such lineups needed in the worst case.	Hard8	IntervalsGreedy+2	No attempts yet	1s	512 MB	Judgeable
ArrayPick one index to change to any integer y, paying \|a_x - y\|, so that the weighted sum of prefix distinct counts plus that cost is minimized.	Hard8	ArrayHash map+2	No attempts yet	5s	256 MB	Judgeable
Edges CountingFor all labeled graphs on n vertices where each component has at most one cycle, sum the number of edges lying on a cycle, modulo p.	Hard8	CombinatoricsMath+2	No attempts yet	2s	256 MB	Judgeable
EquanimousFor each query (l, r), the task sums the integers m in [l, r] grouped by f(m), the minimal absolute signed-digit sum, for values 0 to 9, modulo 1e9+7.	Hard8	Dynamic programmingMath	No attempts yet	2s	256 MB	Judgeable
Square GraphGiven a sequence and a weight for each half-length k, find the minimum spanning forest weight of the graph built from squares whose two halves match.	Hard8	String matchingUnion-find+2	No attempts yet	5s	256 MB	Judgeable
Three DimensionsSum the strange distance d(a,b) over all integer point pairs a and b inside two origin-anchored boxes, output modulo 2^30.	Hard8	Dynamic programmingBit manipulation+1	No attempts yet	1s	256 MB	Judgeable
Cyclic Shift and Minimal InversionsMaintain a permutation under subarray cyclic-shift updates, and after each update report the smallest shift k whose cyclic rotation has the fewest inversions.	Hard8	ArrayDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Filipp RukhovichSum the palindromicity of every subsequence of a string, counting each occurrence of a subsequence, modulo 998244353.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	6s	512 MB	Judgeable
Minimum Spanning Tree of a Grid GraphGiven an n by m grid of integers, build a graph connecting any two cells in the same row or column with edge weight equal to their absolute difference, and output the MST cost.	Hard8	Minimum spanning treeGreedy+2	No attempts yet	2s	512 MB	Judgeable
Mikhail TikhomirovGiven m sets of indices in a length-n array, build a permutation so that each set's values form one contiguous block of size \|S\|.	Hard8	IntervalsDivide and conquer+1	No attempts yet	2s	512 MB	Judgeable
Yum YumFor each rook replaced by the Coach, find the fewest moves needed to eat the most rooks while stepping only on cells outside every rook's row and column.	Hard8	GraphBFS+1	No attempts yet	2s	1024 MB	Judgeable
Tree Transformation PuzzleGiven a ternary-rooted binary tree encoding an arithmetic expression, apply child swaps and root rotations to maximize the expression's value.	Hard8	TreeDynamic programming+2	No attempts yet	2s	1024 MB	Judgeable
Time is MoneyFind the shortest time from cabstand 1 to cabstand n when the k-th taxi pickup costs 2^(k-1) minutes of waiting, modulo 1e9+7.	Hard8	Shortest pathGraph+1	No attempts yet	2s	1024 MB	Judgeable
Two DotsGiven colored points on an L by L square, decide whether every same-colored pair can be joined by non-crossing curves inside the square.	Hard8	GeometrySorting+2	No attempts yet	1s	1024 MB	Judgeable
Vertex Merge GameOn a weighted connected graph, two players alternately color vertices and pick crossing edges; merging continues until one vertex remains. Decide the winner under optimal play.	Hard8	GraphGreedy+2	No attempts yet	3s	1024 MB	Judgeable
Rock Paper Scissors StrategyGiven N players and M games with participant lists and winners, count the strategy assignments (fixed hand, or cyclic RPS pattern) consistent with all results, modulo 1e9+7.	Hard8	ImplementationBrute force+1	No attempts yet	1s	1024 MB	Judgeable
Polygon AreaChoose at most K of N given points to form a simple polygon with maximum area, and print the area to one decimal place.	Hard8	GeometryDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
Dyson CircleGiven n unit-square stars on a grid, find the fewest unit squares forming a corner-connected ring that encloses all stars without edge leaks.	Hard8	GraphShortest path+1	No attempts yet	4s	1024 MB	Judgeable
Flatland OlympicsGiven a track segment and n seat locations, count the ordered pairs of visitors where one seat blocks the other's view of the track.	Hard8	GeometrySorting+1	No attempts yet	4s	1024 MB	Judgeable
IXth ProblemGiven counts of the seven Roman numeral letters, form valid Roman numerals using all tiles while minimizing how many numerals are needed.	Hard8	GreedyMath+1	No attempts yet	1s	1024 MB	Judgeable
Burizon FortA number m is practical when every integer from 1 to m-1 is a sum of distinct divisors of m; decide this for up to 100 values of m up to 10^12.	Hard8	Number theoryMath+2	No attempts yet	1.4s	1024 MB	Judgeable
Screamers in the StormCount sequences of length N with entries in 1..K where every adjacent pair is coprime, modulo 1e9+7, with N up to 1e18.	Hard8	Dynamic programmingMath+2	No attempts yet	2s	1024 MB	Judgeable
Win DieselDig channels in a Mars cave graph by repeatedly visiting the nearest, then safest, room; count the total channel traversals made along the way.	Hard8	GraphBFS+2	No attempts yet	1s	1024 MB	Judgeable
Finding the K-th Tasty Food 2Given three sorted arrays and queries (x, y, z, k), find the k-th smallest value among the first x, y, and z elements and report which array and index it came from.	Hard8	Binary searchDivide and conquer+2	No attempts yet	2s	512 MB	Judgeable
Valid Parenthesis StringA bracket string supports point flips and range queries that count how many ways the characters in [l, r] can be chosen so the whole string becomes a balanced parenthesis sequence.	Hard8	Segment treeCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Leaf MatchingA weighted tree grows by one leaf per query; after each insertion, report the minimum total distance pairing up all leaves, or -1 when the leaf count is odd.	Hard8	TreeGreedy+2	No attempts yet	1s	512 MB	Judgeable
Two-Step Shortest Path 3Find the shortest path from X to Z in a weighted undirected graph that visits at least three of the P given intermediate vertices.	Hard8	GraphShortest path+2	No attempts yet	6s	1024 MB	Judgeable
Territory GrabStarting from any 'A' cell, a growing rectangle piece can extend and then move each turn, avoiding 'X' cells; mark every cell it can ever cover as 'Y'.	Hard8	BFSSimulation+2	No attempts yet	0.5s	512 MB	Judgeable
Sequence (Hard)Sum the products A[B1]...A[BM] over all increasing index tuples B of length M whose chosen values are pairwise distinct, modulo 1e9+7.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	1s	512 MB	Judgeable
Jegi KickingChoose the smallest positive integer K so that applying the teacher's add/subtract rules to all scores makes the total at least S, or report -1 if no K works.	Hard8	Binary searchPrefix sum+2	No attempts yet	1s	512 MB	Judgeable
F1ow3rC0nMaintain an array of flower types under point updates and range queries. For each query, find the minimum number of glue bottles needed to attach petals to trees A through B in order, where each bottle covers one color but can be bought and discarded at will.	Hard8	Segment treeArray+2	No attempts yet	1s	512 MB	Judgeable
A Certain Milk Delivery List (Hard)On a tree, each order adds 1, 2, 3, ... along the path from u to v; after each order, report the running total at a queried node.	Hard8	TreeDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
WombatsGiven an R by C grid where road segments hold wombat counts that change over time, find the fewest wombats on a southward path from the top row to a given bottom intersection.	Hard8	Dynamic programmingDivide and conquer+1	No attempts yet	20s	256 MB	Judgeable
Bazza and ShazzaMaintain a huge implicit grid where cells start at 0; support point assignments and range GCD queries over rectangles, with coordinates up to 1e9 and values up to 1e18.	Hard8	Segment treeDynamic programming+2	No attempts yet	13s	230 MB	Judgeable
Optimal TruckEach customer offers contracts pairing a minimum truck capacity with a profit, at most one per customer; for each target profit, find the smallest capacity reaching it.	Hard8	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
Bookshelf SortingGiven a permutation, repeatedly answer the minimum number of take-and-insert-at-ends moves to sort it, after each of q swaps of two positions.	Hard8	ArrayDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Garbage RobotGiven a room with one sofa, a robot's start cell and direction, count the cells where the robot leaves garbage before it shuts down, for each of q queries.	Hard8	SimulationMath+1	No attempts yet	2s	512 MB	Judgeable
TicketsFor each starting checkpoint, find the minimum total ticket price needed to reach both checkpoint 1 and checkpoint N, or -1 if impossible.	Hard8	Shortest pathSegment tree+1	No attempts yet	2s	1024 MB	Judgeable
HILOSum, over all permutations Elsie could guess with, the number of times the response string contains the substring HILO.	Hard8	CombinatoricsMath+2	No attempts yet	2s	1024 MB	Judgeable
HILOGiven a permutation Elsie uses to guess, count for every possible hidden integer x how many times the response string contains the substring HILO.	Hard8	SimulationImplementation+2	No attempts yet	2s	1024 MB	Judgeable
Closest Cow WinsGiven Nhoj's cow positions, place N of John's cows (not on Nhoj's cows) to maximize the total tastiness of patches John wins.	Hard8	Dynamic programmingSorting+1	No attempts yet	2s	1024 MB	Judgeable
Composite Function and Queries 2Maintain a function f on {1..N} under updates to f(1) and queries asking for the m-fold iterate f^m(x).	Hard8	GraphBinary search+2	No attempts yet	2s	512 MB	Judgeable
Locked DoorsGiven distinct door difficulties in a row of rooms, determine which room is visited K-th when starting from a given room and always opening the easier available door, for many queries.	Hard8	TreeDivide and conquer+2	No attempts yet	40s	1024 MB	Judgeable
Painters' DuelTwo painters alternate moving through a triangular grid of rooms, avoiding blocked rooms, and the task asks for the best score Alma can guarantee under optimal play.	Hard8	Game theoryGraph+1	No attempts yet	40s	1024 MB	Judgeable
Diverse SubarrayGiven an array of trinket types and a cap S, choose a contiguous interval maximizing the number of elements whose type appears at most S times in that interval.	Hard8	Divide and conquerArray+2	No attempts yet	30s	1024 MB	Judgeable
Scrambled WordsCount dictionary words that appear in a generated string, either as-is or with the middle letters permuted and first and last letters fixed.	Hard8	String matchingHash map+2	No attempts yet	Not set	1024 MB	Judgeable
Kickstart AlarmGiven a generated array and K, sum over i=1..K of the total i-th exponential-power of every contiguous subarray, modulo 1e9+7.	Hard8	MathCombinatorics+2	No attempts yet	90s	1024 MB	Judgeable
CandiesFind the maximum-sum contiguous subarray with at most O odd values and total sum at most D, where the values are generated by a linear recurrence.	Hard8	ArrayPrefix sum+2	No attempts yet	40s	1024 MB	Judgeable
ParaglidingGiven towers on the x-axis and balloons in the plane, find the most balloons Edge can collect by gliding at 45 degrees between towers.	Hard8	Dynamic programmingGeometry	No attempts yet	40s	1024 MB	Judgeable
Funniest Word SearchFind the subgrid of a letter grid that maximizes matched word length divided by width plus height, and count the subgrids that reach that maximum.	Hard8	String matchingTrie+2	No attempts yet	240s	1024 MB	Judgeable
Junghoon Wants to Eat Mint Chocolate Jajang RamenGiven a weighted graph and daily starting stores, follow the unique shortest path home (breaking ties toward larger next stores) and report the first store with stock that can sell one ramen, or -1.	Hard8	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
Specializing VillagesAssign each village one of two foods so the average shortest distance to a village of the other food is minimized, and count the optimal assignments.	Hard8	GraphMinimum spanning tree+2	No attempts yet	20s	1024 MB	Judgeable
Combining ClassesGiven N score ranges and Q queries generated by linear recurrences, find the K-th largest score in the merged multiset and output the weighted sum of answers.	Hard8	Binary searchPrefix sum+2	No attempts yet	180s	1024 MB	Judgeable
Let Me Count The WaysCount permutations of 2N distinct people in a row so that none of M specified pairs sit adjacent, modulo 1e9+7.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	40s	1024 MB	Judgeable
Two CubesFind the smallest integer edge length of two axis-parallel cubes so that every sphere lies completely inside at least one of the cubes.	Hard8	Binary searchGeometry+1	No attempts yet	20s	1024 MB	Judgeable
Tricky TriosGiven a face-down deck of 3N cards with three copies each of 1 to N, find the minimum expected number of rounds to remove every trio by flipping cards.	Hard8	ProbabilityGreedy+1	No attempts yet	20s	1024 MB	Judgeable
Seating ChartCount the distinct seating arrangements of N labeled people at K round tables with sizes differing by at most one, where only adjacency matters and table order is irrelevant.	Hard8	CombinatoricsMath+2	No attempts yet	20s	1024 MB	Judgeable
Three-Color GraphGiven a connected weighted graph whose edges are black, red, or blue, add up to X total increments to all red edges and all blue edges to maximize the shortest path from 1 to N.	Hard8	Binary searchShortest path+2	No attempts yet	7s	1024 MB	Judgeable
Funnels and BeakersGiven N stacked funnels that catch water over [L, R] and release it at [M, M+1], find how much water reaches each beaker in Q queries.	Hard8	Segment treeIntervals+1	No attempts yet	4s	1024 MB	Judgeable
Introductions OrganizationGiven which members already know each other, find the fewest minutes until each queried pair can know each other under the session rules, or -1 if it is impossible.	Hard8	GraphShortest path+1	No attempts yet	40s	1024 MB	Judgeable
Theater Seat AssignmentSeat each of the first K customers in a theater of N seats, where each picks the seat farthest from its nearest occupied seat.	Hard8	GreedyBinary search+2	No attempts yet	4s	1024 MB	Judgeable
Algorithm Class - Bubble Sort 6Given arrays A and B, decide whether bubble sort on A produces exactly B at some point within the first K adjacent swaps.	Hard8	SortingSimulation+2	No attempts yet	3s	512 MB	Judgeable
XCopyAssign distinct non-negative integers to each cell of an N by M grid so that neighboring cells differ by exactly one bit, minimizing the largest value used.	Hard8	Bit manipulationMatrix+1	No attempts yet	2s	1024 MB	Judgeable
DungeonsGiven a grid with several possible starting cells and hidden mines, find the most coins a player can guarantee without knowing the start.	Hard8	Bit manipulationGraph+2	No attempts yet	2s	1024 MB	Judgeable
JoitterGiven each user's diary visibility level and pairwise friendship costs, find the minimum number of friendship registrations so everyone can read all diaries, and the minimum cost for that count.	Hard8	GraphGreedy+2	No attempts yet	1s	1024 MB	Judgeable
KeycardsCount the subsets of the 2N possible keys (a nonempty collection) such that exactly K of the N positions are punched in every chosen key, modulo 1e9+7.	Hard8	CombinatoricsMath+1	No attempts yet	1s	1024 MB	Judgeable
ReportEach person reports job i to a fixed target, and the report keeps forwarding until a repeat. For each person, output how many distinct jobs' reports reached them before they start their own job.	Hard8	GraphDFS+2	No attempts yet	0.5s	1024 MB	Judgeable
UFO Airport (UFO) 3Place as many copies of a small B by D UFO shape as possible on a W by H grid so that each copy lies on landable cells and no two copies share an edge.	Hard8	BacktrackingBrute force+2	No attempts yet	1s	1024 MB	Judgeable
UFO Landing Field (UFO) 5Place as many small fixed-shape UFOs as possible in a grid of landable cells, with the twist that no two placed UFOs may share an edge.	Hard8	Brute forceGreedy+2	No attempts yet	1s	1024 MB	Judgeable
OrienteeringGiven a DAG whose edges go from lower to higher altitude, find two paths from 1 to N that together cover every checkpoint, minimizing the total length.	Hard8	Dynamic programmingGraph+2	No attempts yet	1s	1024 MB	Judgeable
SengokuCount the cells of an L by L grid covered by at least one of N diagonal watchmen, where a watchman at (x, y) covers every cell with \|x-i\| = \|y-j\|.	Hard8	GeometrySorting+1	No attempts yet	0.75s	1024 MB	Judgeable
RegionsSplit a weighted tree into M connected regions to minimize the largest region diameter, and output that minimum value.	Hard8	Binary searchTree+2	No attempts yet	1s	1024 MB	Judgeable
Finals Venue (Finals)Choose K cities as finals venues so that every contestant can reach one, minimizing total toll; sharing a road lets travelers split the cost, which reduces to a minimum spanning forest problem.	Hard8	GraphMinimum spanning tree+2	No attempts yet	1s	1024 MB	Judgeable