Problems

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Total results29,440 problems

Building a Swimming Pool
Medium6
Heap, BFS+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Minimum Difference to a Perfect Permutation
Medium6
Math, Graph+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Painting 1
Medium6
Geometry, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Height Arrangement
Medium6
Sorting, Greedy+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
News Broadcast
Medium6
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Fences
Medium6
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Pizza
Medium6
Geometry, Brute force+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Zigzag Lineup
Medium6
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Making Words
Medium6
String, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Team Formation
Medium6
Graph, BFS+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Random Number Generator
Medium6
Math, Recursion+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Road Paving
Medium6
Shortest path, Graph+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Word Puzzle
Medium6
Trie, Backtracking+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Delivery
Medium6
BFS, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Student Shuffle
Medium6
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Moonlit Maze Escape
Medium6
BFS, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Code Collection
Medium6
Probability, Math+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Euler Circuit
Medium6
Graph, DFS+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
NMK
Medium6
Combinatorics, Greedy+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Jewel Thief
Medium6
Greedy, Heap+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Subsequence Sum Count 2
Medium6
Brute force, Binary search+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Incorrect Josephus Code
Medium6
Number theory, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Hexagonal Numbers
Medium6
Dynamic programming, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
String Distance
Medium6
Dynamic programming, String+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Christmas Tree
Medium6
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Finding a Sequence from a Sign Matrix
Medium6
Prefix sum, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Problem Assignment
Medium6
Dynamic programming, Graph+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Restricted Permutations
Medium6
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Installing Power Plant Cables
Medium6
Shortest path, Graph+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Theater
Medium6
Bit manipulation, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Tree Planting
Medium6
Segment tree, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Coin Flipping
Medium6
Bit manipulation, Brute force+2
No attempts yet
Time limit
6s
Memory limit
128 MB
Judgeable
Can You Do Arithmetic?
Medium6
String, Stack+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Sum of Tree Path Weights
Medium6
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Barracks
Medium6
Math, Greedy+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
String Decoration
Medium6
Greedy, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Regions
Medium6
Graph, Intervals+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Assigning Tasks 1
Medium6
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Composite Prime
Medium6
Backtracking, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Poker
Medium6
Combinatorics, Brute force+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Soldiers
Medium6
Segment tree, Binary search+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Picking Trash in the Same Increasing Order
Medium6
Dynamic programming, Array+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Next Palindrome Number
Medium6
String, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Friendly Brothers
Medium6
Number theory, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Sum and Product
Medium6
Math, Binary search
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Infinite Sequence 2
Medium6
Recursion, Math+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Cutting a Cake with a Hole
Medium6
Geometry, Union-find+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Undo
Medium6
Stack, Simulation+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Optimal Binary Search Tree
Medium6
Dynamic programming, Tree+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Guitar Chord
Medium6
Math, Greedy+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Lecture Rooms 2
Medium6
Greedy, Heap+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Password Attempt Count
Medium6
Math, String+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Treasure Location
Medium6
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Random Robot
Medium6
Dynamic programming, Brute force+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sum of Largest Power-of-Two Divisors
Medium6
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Painting Points
Medium6
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Making Roads One-Way
Medium6
Graph, DFS+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Candy
Medium6
Dynamic programming, Number theory+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Parliamentary Election
Medium6
Greedy, Array+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
God of Numbers
Medium6
Greedy, Sorting+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Character Training
Medium6
Dynamic programming, Greedy+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Card Placement
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Graph Relabeling
Medium6
Topological sort, Greedy+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Chemical Experiment
Medium6
Greedy, Sorting+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Movie Director Shom
Medium6
Binary search, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Smallest Rectangle
Medium6
Geometry, Brute force+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Counting Divisible Numbers
Medium6
Combinatorics, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Nice Numbers
Medium6
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Coin Flips II
Medium6
Matrix, Greedy+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Almost Prime
Medium6
Number theory, Math+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Exact Divisors
Medium6
Number theory, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Prefix Reversal 3
Medium6
String, Greedy+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Deleting Digits
Medium6
Greedy, Stack+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Maze Escape
Medium6
BFS, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Shom Square
Medium6
Backtracking, Greedy+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Shomtring
Medium6
Greedy, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Absolute Value Sequence
Medium6
Number theory, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Periodic Prefixes
Medium6
String matching, String+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Number Connection Puzzle
Medium6
Backtracking, Graph+1
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Turning On the Lights
Medium6
Bit manipulation, Brute force+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Minho's Curiosity
Medium6
Shortest path, Graph+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Race
Medium6
Binary search, Greedy
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Palindrome Partitioning
Medium6
Dynamic programming, String
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Making a Number
Medium6
Greedy, String+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Sum of Lucky Numbers
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Dongmin Sequence
Medium6
Matrix, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Coin Exchange
Medium6
Greedy, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Anti-Palindrome
Medium6
Greedy, String+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Making Primes
Medium6
Backtracking, Brute force+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Factorial 5
Medium6
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Covering Points with a Square
Medium6
Geometry, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Tree Encoding
Medium6
Combinatorics, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Position Exchange
Medium6
BFS, Graph+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Rockstar Rock Dongho
Medium6
Graph, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Artist Lee Dongho
Medium6
Dynamic programming, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Escape the Hazard Zones
Medium6
BFS, Graph+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Substitution Sequence Range Counts
Medium6
Recursion, Divide and conquer+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Making the Best Phone Number
Medium6
Dynamic programming, String+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Monkey Who Wants to Move Like a Horse
Medium6
BFS, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Longest Repeated Substring
Medium6
Binary search, String matching+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Building a Swimming PoolGiven an N by M grid of pillar heights 1 to 9, count the total water trapped on top after water flows off any path to the outside.	Medium6	HeapBFS+2	No attempts yet	2s	128 MB	Judgeable
Minimum Difference to a Perfect PermutationGiven a permutation, determine the minimum number of positions to change so it becomes a single N-cycle, which is the condition for a 'perfect permutation'.	Medium6	MathGraph+2	No attempts yet	2s	128 MB	Judgeable
Painting 1Compute the unpainted area of a paper after one vertical fold and c horizontal accordion folds, then painting a rectangle and unfolding.	Medium6	GeometryMath+2	No attempts yet	2s	128 MB	Judgeable
Height ArrangementArrange N heights around a circular table so the maximum difference between adjacent people is minimized, breaking ties by lexicographically smallest order.	Medium6	SortingGreedy+2	No attempts yet	2s	128 MB	Judgeable
News BroadcastGiven a rooted tree, each informed employee calls one subordinate at a time, each call lasting one minute; find the minimum time until every employee knows the news.	Medium6	TreeDFS+2	No attempts yet	2s	128 MB	Judgeable
FencesPartition up to 16 given fence lengths into disjoint triples, keep only triples that form a valid triangle, and maximize the total area.	Medium6	Dynamic programmingBit manipulation+2	No attempts yet	2s	128 MB	Judgeable
PizzaCount lines through the origin that reflect a set of pizza toppings onto themselves, printing -1 if infinitely many such lines exist.	Medium6	GeometryBrute force+2	No attempts yet	2s	128 MB	Judgeable
Zigzag LineupCount permutations of N distinct heights where adjacent comparisons strictly alternate, modulo 1,000,000.	Medium6	Dynamic programmingCombinatorics+1	No attempts yet	2s	128 MB	Judgeable
Making WordsFor each 3x3 letter board, find which center letters yield the fewest and the most dictionary words of length 4 or more, along with those counts.	Medium6	StringBit manipulation+2	No attempts yet	1s	128 MB	Judgeable
Team FormationGiven pairs of students who know each other, decide if all students can be split into two teams where every same-team pair is acquainted, and output one valid split.	Medium6	GraphBFS+1	No attempts yet	2s	128 MB	Judgeable
Random Number GeneratorGiven a linear congruential generator with huge parameters up to 10^18, compute the n-th term modulo m and then modulo g using fast exponentiation.	Medium6	MathRecursion+2	No attempts yet	2s	128 MB	Judgeable
Road PavingFind the minimum travel time from city 1 to city N when up to K roads can be paved to cost zero, using layered shortest-path search over (node, paves used).	Medium6	Shortest pathGraph+1	No attempts yet	2s	128 MB	Judgeable
Word PuzzleCount how many words from a fixed dictionary can be spelled by paths of adjacent, non-repeating cells in a 5x5 letter grid.	Medium6	TrieBacktracking+2	No attempts yet	2s	128 MB	Judgeable
DeliveryFind the minimum moves in a grid from a start cell to visit two target cells, forbidding two consecutive moves in the same direction.	Medium6	BFSShortest path+2	No attempts yet	2s	128 MB	Judgeable
Student ShuffleCount permutations of up to 16 students so that every pair of adjacent heights differs by more than a given value K.	Medium6	Dynamic programmingBit manipulation+2	No attempts yet	2s	128 MB	Judgeable
Moonlit Maze EscapeFind the shortest path from start to any exit in a grid maze where doors need matching keys collected along the way, tracked as key-state BFS.	Medium6	BFSBit manipulation+1	No attempts yet	2s	128 MB	Judgeable
Code CollectionGiven N possible codes and target K distinct codes, compute the expected number of independent uniform draws needed to collect at least K distinct codes, with N up to 10^18.	Medium6	ProbabilityMath+1	No attempts yet	2s	256 MB	Judgeable
Euler CircuitGiven an adjacency matrix with possible multi-edges, output a valid Euler circuit or -1 if none exists.	Medium6	GraphDFS+1	No attempts yet	3s	512 MB	Judgeable
NMKConstruct a permutation of 1..N whose longest increasing subsequence is exactly M and longest decreasing subsequence is exactly K, or report impossible.	Medium6	CombinatoricsGreedy+2	No attempts yet	2s	128 MB	Judgeable
Jewel ThiefGiven N jewels with weight and value and K bags with weight limits (one jewel per bag), maximize total value stolen using a greedy plus max-heap approach.	Medium6	GreedyHeap+1	No attempts yet	1s	256 MB	Judgeable
Subsequence Sum Count 2Count the number of non-empty subsequences of up to 40 integers whose sum equals a given target S using a meet-in-the-middle approach.	Medium6	Brute forceBinary search+2	No attempts yet	1s	256 MB	Judgeable
Incorrect Josephus CodeGiven n and k up to 1e9, compute the sum of k mod i for i from 1 to n efficiently using divisor block decomposition.	Medium6	Number theoryMath+1	No attempts yet	2s	128 MB	Judgeable
Hexagonal NumbersGiven N up to 1,000,000, compute the minimum number of hexagonal numbers (1, 6, 15, 28, ...) that sum to N.	Medium6	Dynamic programmingMath+2	No attempts yet	2s	128 MB	Judgeable
String DistanceGiven strings O and N, find the minimum number of substring-insertion operations to turn O into N, or output -1 if impossible.	Medium6	Dynamic programmingString+2	No attempts yet	2s	128 MB	Judgeable
Christmas TreeCount the ways to decorate an N-level tree where level k needs k ornaments split evenly among chosen colors, given limited red, green and blue ornaments.	Medium6	Dynamic programmingCombinatorics+1	No attempts yet	2s	128 MB	Judgeable
Finding a Sequence from a Sign MatrixGiven the sign pattern of all subarray sums of a hidden integer sequence, reconstruct one integer sequence (values -10 to 10) that produces the same sign matrix.	Medium6	Prefix sumMath+2	No attempts yet	2s	128 MB	Judgeable
Problem AssignmentGiven an N x N matrix of student-problem times, find the minimum-cost perfect matching assigning one distinct problem to each student.	Medium6	Dynamic programmingGraph+2	No attempts yet	5s	128 MB	Judgeable
Restricted PermutationsCount permutations of 1..N where every element differs from its index by at most K, using a bitmask DP over a sliding window.	Medium6	Dynamic programmingBit manipulation+2	No attempts yet	2s	128 MB	Judgeable
Installing Power Plant CablesFind the minimum total length of new cables needed to connect plant 1 to plant N, using free existing cables and new links capped at length M, via shortest path.	Medium6	Shortest pathGraph+1	No attempts yet	2s	128 MB	Judgeable
TheaterConstruct the longest sequence of distinct nonempty actor subsets where consecutive scenes differ by exactly one actor and the play starts and ends with a single actor.	Medium6	Bit manipulationCombinatorics+2	No attempts yet	2s	128 MB	Judgeable
Tree PlantingPlant trees in order and compute the product, modulo 1e9+7, of the sum of distances from each new tree to all previously planted trees.	Medium6	Segment treePrefix sum+1	No attempts yet	2s	128 MB	Judgeable
Coin FlippingGiven an N by N grid of H/T coins (N up to 20), find the minimum number of tails achievable by flipping any subset of rows and columns.	Medium6	Bit manipulationBrute force+2	No attempts yet	6s	128 MB	Judgeable
Can You Do Arithmetic?Parse and evaluate an arithmetic expression with +,-,*,/ and parentheses, respecting precedence, and print ROCK if the expression is invalid or divides by zero.	Medium6	StringStack+2	No attempts yet	2s	128 MB	Judgeable
Sum of Tree Path WeightsGiven a weighted tree, compute the sum over all vertex pairs of the product of edge weights along their connecting path, modulo 1e9+7.	Medium6	TreeDFS+2	No attempts yet	2s	128 MB	Judgeable
BarracksFind the minimum number of turns for N marines to destroy a barracks with health B that spawns U enemy marines per turn, or report -1 if impossible.	Medium6	MathGreedy+1	No attempts yet	2s	128 MB	Judgeable
String DecorationGiven N words that can each be cut into ordered pieces and interleaved freely, find the lexicographically smallest concatenation of all pieces.	Medium6	GreedyString+1	No attempts yet	1s	128 MB	Judgeable
RegionsGiven N cities linked by a chain of express roads plus extra directed roads, split cities into equal-size regions that preserve a strict one-way reachability order, maximizing region count.	Medium6	GraphIntervals+2	No attempts yet	2s	128 MB	Judgeable
Assigning Tasks 1Given an N by N cost matrix, assign each person exactly one task to minimize the total assignment cost.	Medium6	Dynamic programmingBit manipulation+1	No attempts yet	1s	512 MB	Judgeable
Composite PrimeGiven up to 1e5 queries with N as large as 10^7, find the largest composite number at most N whose every proper contiguous digit substring of length 2 or more is prime.	Medium6	BacktrackingMath+2	No attempts yet	1s	1024 MB	Judgeable
PokerCompute the exact probability of each of 12 six-card poker hand rankings, including custom back straight and royal straight flush definitions, as reduced fractions.	Medium6	CombinatoricsBrute force+2	No attempts yet	2s	128 MB	Judgeable
SoldiersMaintain unit sizes under point updates and answer queries for which unit contains a given soldier serial number using prefix sums.	Medium6	Segment treeBinary search+2	No attempts yet	1s	256 MB	Judgeable
Picking Trash in the Same Increasing OrderFind the longest common strictly increasing subsequence of trash sizes recorded on two different days.	Medium6	Dynamic programmingArray+1	No attempts yet	2s	128 MB	Judgeable
Next Palindrome NumberGiven a positive integer with up to 50 digits, construct the smallest palindrome number strictly greater than it.	Medium6	StringMath+2	No attempts yet	2s	128 MB	Judgeable
Friendly BrothersGiven a reduced fraction a/b, find the shortest repeating turn pattern (length at most 60) of two people eating half the remaining cake so one person's total share equals a/b.	Medium6	Number theoryMath+2	No attempts yet	2s	128 MB	Judgeable
Sum and ProductGiven a sum S and a product P, find the smallest list of nonnegative reals whose sum is S and product is P, or report -1 if impossible.	Medium6	MathBinary search	No attempts yet	2s	128 MB	Judgeable
Infinite Sequence 2Compute A_N for a recursively defined sequence using nested floor divisions, requiring memoized recursion over a bounded set of distinct arguments.	Medium6	RecursionMath+2	No attempts yet	10s	512 MB	Judgeable
Cutting a Cake with a HoleGiven a square cake with a smaller square hole in its center, count how many pieces result from horizontal and vertical full-line cuts that only affect actual cake material.	Medium6	GeometryUnion-find+2	No attempts yet	1s	128 MB	Judgeable
UndoSimulate a text editor whose undo command reverts every command from the previous t seconds, where undos themselves can be undone, and find the final text.	Medium6	StackSimulation+2	No attempts yet	2s	128 MB	Judgeable
Optimal Binary Search TreeGiven up to 300 distinct keys within range 1..n, build a binary search tree minimizing total node visits over all searches for every integer from 1 to n, using an optimal BST DP with unsuccessful search gaps.	Medium6	Dynamic programmingTree+1	No attempts yet	2s	128 MB	Judgeable
Guitar ChordGiven each guitar string's open note and a target chord, choose which chord note each string plays to minimize the pressed-fret range needed to cover all chord notes.	Medium6	MathGreedy+2	No attempts yet	2s	128 MB	Judgeable
Lecture Rooms 2Assign each of N intervals a room number using the minimum number of rooms so overlapping lectures never share a room, touching endpoints allowed.	Medium6	GreedyHeap+2	No attempts yet	2s	128 MB	Judgeable
Password Attempt CountGiven a fixed alphabet order and a password, compute the attempt number at which that string appears in the length-then-lexicographic enumeration, modulo 900528.	Medium6	MathString+2	No attempts yet	2s	128 MB	Judgeable
Treasure LocationSimulate K rounds of moving forward by the digital root of successive powers of M and turning right, then output the final coordinate for K up to 10^9.	Medium6	MathNumber theory+2	No attempts yet	2s	128 MB	Judgeable
Random RobotGiven move probabilities for E, W, S, N and up to 14 steps, compute the probability that the robot's random walk visits no grid cell twice.	Medium6	Dynamic programmingBrute force+1	No attempts yet	1s	128 MB	Judgeable
Sum of Largest Power-of-Two DivisorsGiven A and B up to 10^15, compute the sum over that range of the largest power-of-two divisor of each integer.	Medium6	MathNumber theory+2	No attempts yet	2s	128 MB	Judgeable
Painting PointsFind a rotation angle and a red/blue coloring of circle points so rotated red points exactly match blue points, maximizing total painted points.	Medium6	MathNumber theory+2	No attempts yet	2s	128 MB	Judgeable
Making Roads One-WayDecide if every two-way road between N cities can be made one-way so that no directed cycle remains in the whole road network.	Medium6	GraphDFS+1	No attempts yet	2s	128 MB	Judgeable
CandyGiven candy prices, count the distinct ways to pick a multiset of candies whose price sum is a prime number.	Medium6	Dynamic programmingNumber theory+2	No attempts yet	2s	128 MB	Judgeable
Parliamentary ElectionGiven vote counts for N candidates, find the minimum number of voters candidate 1 must bribe so her total strictly exceeds every other candidate's total.	Medium6	GreedyArray+1	No attempts yet	2s	128 MB	Judgeable
God of NumbersChoose N numbers from K given natural numbers, using every distinct input at least once, and arrange them to concatenate into the largest possible number.	Medium6	GreedySorting+1	No attempts yet	2s	128 MB	Judgeable
Character TrainingGiven character counts and power values per level, decide how to spend at most D training days across characters to maximize total power.	Medium6	Dynamic programmingGreedy+1	No attempts yet	2s	128 MB	Judgeable
Card PlacementAssign N cards with numbers and letters to N ordered bins under a numeric constraint to build the lexicographically smallest string, or report impossibility.	Medium6	GreedySorting+2	No attempts yet	2s	128 MB	Judgeable
Graph RelabelingGiven a directed graph as an adjacency matrix, assign each vertex a distinct label from 1 to N respecting all edge order constraints, and output the lexicographically smallest label sequence or -1 if impossible.	Medium6	Topological sortGreedy+2	No attempts yet	2s	128 MB	Judgeable
Chemical ExperimentGiven bottles with known concentrations and volumes, find the maximum volume of an exact target-concentration mixture obtainable by taking any partial amounts from each bottle.	Medium6	GreedySorting+1	No attempts yet	2s	128 MB	Judgeable
Movie Director ShomFind the N-th smallest positive integer whose decimal digits contain at least three consecutive 6s, for N up to 10000.	Medium6	Binary searchDynamic programming+2	No attempts yet	2s	128 MB	Judgeable
Smallest RectangleFind the minimum area axis-aligned rectangle with integer coordinates whose strict interior contains at least half of N given points.	Medium6	GeometryBrute force+2	No attempts yet	2s	128 MB	Judgeable
Counting Divisible NumbersCount integers in a range that are divisible by at least one element of a given array using inclusion-exclusion over subsets and LCM.	Medium6	CombinatoricsMath+2	No attempts yet	2s	128 MB	Judgeable
Nice NumbersCount integers in the range [L, R] whose binary representation has three consecutive equal bits, using digit DP over bits.	Medium6	Dynamic programmingBit manipulation+1	No attempts yet	2s	128 MB	Judgeable
Coin Flips IIGiven an N by M grid of coins, find the minimum number of top-left rectangle flips needed to turn every coin to heads.	Medium6	MatrixGreedy+1	No attempts yet	2s	128 MB	Judgeable
Almost PrimeCount integers of the form p^N (p prime, N greater than or equal to 2) that fall within a range [A, B] with B up to 10^14.	Medium6	Number theoryMath+1	No attempts yet	2s	256 MB	Judgeable
Exact DivisorsSum, for every integer from A to A+B, the count of proper divisors K such that K raised to the power N does not divide that integer.	Medium6	Number theoryMath+1	No attempts yet	2s	128 MB	Judgeable
Prefix Reversal 3Given a string, for each prefix length from 1 to N in order you may choose to reverse that prefix, and you must output the lexicographically smallest string achievable after all choices.	Medium6	StringGreedy+2	No attempts yet	2s	128 MB	Judgeable
Deleting DigitsGiven a digit string and a required count of each digit to delete, remove exactly that many occurrences of each digit to leave the numerically largest possible string.	Medium6	GreedyStack+2	No attempts yet	2s	128 MB	Judgeable
Maze EscapeFind the minimum time to escape a maze where the player can press a button to rotate an entire row and column of rooms by 90 degrees, changing their door layout.	Medium6	BFSBit manipulation+2	No attempts yet	2s	128 MB	Judgeable
Shom SquareConstruct the lexicographically smallest N by N grid using digits 0 to D-1 so every row and column contains all D values at least once.	Medium6	BacktrackingGreedy+1	No attempts yet	2s	128 MB	Judgeable
ShomtringGiven limits on total A's, total B's, and the longest allowed run of each, compute the maximum length string built only from A and B.	Medium6	GreedyMath+1	No attempts yet	2s	128 MB	Judgeable
Absolute Value SequenceGiven the first two terms of a sequence where each later term is the absolute difference of the two before it, answer up to 50 queries for S_i with i as large as 10^18.	Medium6	Number theoryMath+1	No attempts yet	2s	128 MB	Judgeable
Periodic PrefixesFor each prefix of a string, find the largest count n such that the prefix is some substring repeated n times, using prefix-function techniques.	Medium6	String matchingString+1	No attempts yet	2s	128 MB	Judgeable
Number Connection PuzzleFind a Hamiltonian path on an m by n grid (both even, up to 8) connecting two given endpoints, moving only to adjacent cells without crossing itself, or report -1.	Medium6	BacktrackingGraph+1	No attempts yet	5s	128 MB	Judgeable
Turning On the LightsFind the minimum number of bulb presses, each flipping a cell and its 8 neighbors, needed to turn all bulbs on an N×M grid (N,M ≤ 8) on, or report impossibility.	Medium6	Bit manipulationBrute force+2	No attempts yet	2s	128 MB	Judgeable
Minho's CuriosityGiven an all-pairs shortest-time matrix for N cities, reconstruct the minimum-edge road network with the same shortest times and output the total edge weight, or -1 if impossible.	Medium6	Shortest pathGraph+1	No attempts yet	2s	128 MB	Judgeable
RaceBinary search the maximum minimum gap achievable by placing M judges among K fixed points on a length-N track, then output the lexicographically largest valid arrangement.	Medium6	Binary searchGreedy	No attempts yet	2s	512 MB	Judgeable
Palindrome PartitioningGiven an uppercase string up to length 2500, compute the minimum number of pieces to cut it into palindromic substrings.	Medium6	Dynamic programmingString	No attempts yet	2s	128 MB	Judgeable
Making a NumberGiven how many cards exist for each digit 0-9, build the largest possible number using some or all cards so that no two adjacent digits match and no leading zero appears.	Medium6	GreedyString+1	No attempts yet	2s	128 MB	Judgeable
Sum of Lucky NumbersWrite N as a sum of the fewest numbers made only of digits 4 and 7, breaking ties by the lexicographically smallest sequence.	Medium6	Dynamic programmingGreedy+2	No attempts yet	2s	128 MB	Judgeable
Dongmin SequenceCount sequences of lucky numbers (digits 4/7 only) chosen from a given list of length L, where consecutive elements share first/last digit, modulo 1,234,567,891.	Medium6	MatrixDynamic programming+2	No attempts yet	2s	128 MB	Judgeable
Coin ExchangeFind the minimum number of fixed-rate gold/silver/bronze coin exchanges needed to reach required minimum amounts of each coin, or report impossibility.	Medium6	GreedyMath+1	No attempts yet	2s	128 MB	Judgeable
Anti-PalindromeRearrange all characters of a string to form the lexicographically smallest anti-palindrome, where each pair of symmetric positions must differ, or report impossible.	Medium6	GreedyString+2	No attempts yet	2s	128 MB	Judgeable
Making PrimesCombine all N (up to 6) given numbers with +,-,*,/ and parentheses in every possible way to find the smallest and largest prime value obtainable.	Medium6	BacktrackingBrute force+2	No attempts yet	2s	128 MB	Judgeable
Factorial 5Compute N! for N up to one million, strip all trailing zeros, and output the last five digits of what remains, zero-padded.	Medium6	MathNumber theory+2	No attempts yet	2s	128 MB	Judgeable
Covering Points with a SquareGiven up to 50 points, decide whether an axis-aligned square's four sides can cover every point and output its side length, or -1 if no such square exists.	Medium6	GeometryMath+2	No attempts yet	2s	128 MB	Judgeable
Tree EncodingGiven N and an index, find the k-th lexicographically smallest preorder traversal string among all binary search trees built from the first N letters, using Catalan number counting.	Medium6	CombinatoricsMath+2	No attempts yet	2s	128 MB	Judgeable
Position ExchangeFind the minimum number of simultaneous turns for two players on a grid to swap starting cells, moving in 8 directions while avoiding walls, collisions, and direct swaps, using BFS over joint position states.	Medium6	BFSGraph+2	No attempts yet	2s	128 MB	Judgeable
Rockstar Rock DonghoGiven counts of songs by their fast/slow start and end tempos, find the longest ordering of distinct songs into a valid chain that must begin with a fast-starting song if any exists.	Medium6	GraphMath+1	No attempts yet	2s	128 MB	Judgeable
Artist Lee DonghoGiven a black/white grid and a limit on horizontal single-color brush strokes, find the minimum number of cells that end up unpainted or wrongly colored.	Medium6	Dynamic programmingPrefix sum+2	No attempts yet	2s	128 MB	Judgeable
Escape the Hazard ZonesGiven overlapping rectangular zones on a 501x501 grid marking safe, dangerous, and blocked cells, find the minimum life lost moving from (0,0) to (500,500).	Medium6	BFSGraph+2	No attempts yet	2s	128 MB	Judgeable
Substitution Sequence Range CountsCount occurrences of 1, 2, 3 in a fixed interval of a sequence generated by simultaneous ternary substitution after N steps, without building the whole sequence.	Medium6	RecursionDivide and conquer+2	No attempts yet	2s	128 MB	Judgeable
Making the Best Phone NumberSplit a digit string into groups of 2 or 3 to maximize a score based on group types, then output the lexicographically smallest optimal formatting.	Medium6	Dynamic programmingString+2	No attempts yet	2s	128 MB	Judgeable
Monkey Who Wants to Move Like a HorseFind the minimum number of moves for a monkey to reach the bottom-right cell of a grid using normal steps and at most K knight-like jumps over obstacles.	Medium6	BFSShortest path+2	No attempts yet	2s	256 MB	Judgeable
Longest Repeated SubstringFind the length of the longest substring that occurs at least twice in a given string of up to 200,000 lowercase letters.	Medium6	Binary searchString matching+2	No attempts yet	2s	128 MB	Judgeable