Problems

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Total results3,685 problems

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Building a ranchGiven an M by N grid with trees and rocks as obstacles, find the side length of the largest square subgrid that contains no obstacle.	Medium5	Dynamic programmingMatrix+2	No attempts yet	1s	512 MB	Judgeable
EnigmaGiven a digit pattern with question marks and an N, find the smallest matching number with no leading zero that is divisible by N.	Medium5	Dynamic programmingMath+2	No attempts yet	1s	1024 MB	Judgeable
Front NineGiven a clamped random walk on [0,h] with step probabilities, compute the expected area under the piecewise-linear terrain over n steps.	Medium5	ProbabilityDynamic programming+2	No attempts yet	6s	512 MB	Judgeable
TilingCount the ways to tile a 3 by W rectangle with 2 by 1 dominoes, printing the result modulo 1e9+7.	Medium5	Dynamic programmingCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Sweet, sour, bitter, saltyCut edges of a rooted binary tree so that at least X resulting components each contain at least K nodes, minimizing total cut cost.	Medium5	TreeDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Candy ChainGiven a candy string and a list of paid parts (each reversible), find the maximum total value obtainable by repeatedly removing sold parts and rejoining the remainder.	Medium5	Dynamic programmingIntervals+2	No attempts yet	7s	512 MB	Judgeable
SugorokuSquares 2 to N+1 are each marked 0 or 1; find the smallest die size j such that some sequence of rolls from 1 to j reaches or passes square N+2 without landing on any square marked 1.	Medium5	Dynamic programmingBFS+2	No attempts yet	2s	512 MB	Judgeable
Hangul LCSGiven two Hangul strings of up to 1000 characters each, compute the length of their longest common subsequence in characters.	Medium5	Dynamic programmingString+2	No attempts yet	2s	512 MB	Judgeable
Counting a^i b^j c^k subsequencesCount subsequences of a string of a, b, c that read as some positive number of a's, then b's, then c's, modulo 1e9+7.	Medium5	Dynamic programmingString+1	No attempts yet	2s	512 MB	Judgeable
Consultations before resignationGiven up to 1.5 million days, each with a job of length T_i and pay P_i, pick jobs that fit before day N+1 to maximize total pay.	Medium5	Dynamic programmingArray+2	No attempts yet	2s	512 MB	Judgeable
Probability that the knight stays on the boardA knight on an N by N board makes K random moves, each of the eight directions equally likely; find the probability it is still on the board after K moves.	Medium5	Dynamic programmingProbability+2	No attempts yet	2s	512 MB	Judgeable
Pascal's triangleBuild Pascal's triangle and sum all entries inside the equilateral sub-triangle whose top cell is row R, position C, with side length W.	Medium5	ArrayDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Signal 1Choose a subset of points with distinct x-coordinates; maximize the total Euclidean length of the polyline joining them in increasing x order.	Medium5	Dynamic programmingSorting+2	No attempts yet	1.5s	128 MB	Judgeable
Roasting Emma is a barista tooGiven a weighted tree, compute for every vertex the sum of shortest distances to all other vertices.	Medium5	TreeDFS+2	No attempts yet	1.5s	128 MB	Judgeable
QueryreuQMaintain a string under append and pop-back operations, and after each operation print the number of palindromic substrings it contains.	Medium5	StringDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
Drain PipesCount the number of ways to pick quantities of each pipe type, within the given stock, so the chosen pipes sum to exactly x.	Medium5	Dynamic programmingArray+2	No attempts yet	1s	128 MB	Judgeable
Ah-Choo!Compute the least Dynamic Time Warping distance between two equal-length integer sequences, where every point must match at least one point of the other and matches cannot cross.	Medium5	Dynamic programmingArray+1	No attempts yet	1s	512 MB	Judgeable
Pen Pineapple Apple PenGiven a string of A, P, and p, find the maximum number of disjoint subsequence occurrences of the pattern p, P, A, p in order.	Medium5	GreedyString+1	No attempts yet	1s	32 MB	Judgeable
Uks Is an Apple Fan!!Count the number of paths on an N by M grid where each cell directs movement right, down, or both, and every path must end at cell (N, M).	Medium5	Dynamic programmingCombinatorics+1	No attempts yet	2s	512 MB	Judgeable
Longest Consecutive SubsequenceGiven an integer sequence, find the longest subsequence whose values form an arithmetic run with common difference 1, keeping the original order.	Medium5	Dynamic programmingHash map+1	No attempts yet	2s	256 MB	Judgeable
1, 2, 3 Sum 5Count the ordered sums of 1, 2, and 3 that add to n, with no equal value adjacent, modulo 1,000,000,009.	Medium5	Dynamic programmingMath+2	No attempts yet	1s	512 MB	Judgeable
1, 2, 3 Addition 7Count ordered compositions of n into exactly m parts, where each part is 1, 2, or 3, modulo 1,000,000,009.	Medium5	Dynamic programmingCombinatorics+2	No attempts yet	0.25s	512 MB	Judgeable
BlogGiven a string of R, G, and B, find the minimum number of contiguous same-color paint operations needed to build it.	Medium5	Dynamic programmingString+2	No attempts yet	1s	256 MB	Judgeable
A Great WayFind the cheapest path from node 1 to node N, where an edge costs c + d*max(0,e-10), breaking ties by fewer waypoints.	Medium5	GraphShortest path+1	No attempts yet	1s	128 MB	Judgeable
Execution TimeGiven ranks and operating speeds of n computers in a chain of ranks, compute when the whole task finishes using transmission time (i-j)^2 between machines.	Medium5	Dynamic programmingGraph+1	No attempts yet	2s	128 MB	Judgeable
Adding 1, 2, 3 (9)Count ordered compositions of n into parts 1, 2, and 3 that use at most m terms, and output each count modulo 1,000,000,009.	Medium5	Dynamic programmingCombinatorics+2	No attempts yet	1s	512 MB	Judgeable
Bit Palindromic NumbersCount integers in [l, r] whose first and last decimal digits match; solve with per-length counts and digit-DP over 10^18 ranges.	Medium5	MathDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Amusement ParkCitizens at various blocks must reach block 0 by taxi (A per block, one rider) or by sharing a bus (B won, up to 40 riders, one pick-up point). Find the minimum total cost.	Medium5	Dynamic programmingSorting+2	No attempts yet	1s	256 MB	Judgeable
Making a PalindromeFind the largest odd-length palindrome centered at index i, then answer each query by dropping the rest of the N cards.	Medium5	String matchingDynamic programming+1	No attempts yet	1s	512 MB	Judgeable
Cheap TripsOrder trips cannot be reordered and take no gaps; plan discounts across 120-minute windows to minimize total cost.	Medium5	Dynamic programmingGreedy	No attempts yet	2s	512 MB	Judgeable
TeamworkPartition cows in a row into blocks of at most K so each block contributes its maximum times block size; maximize the sum.	Medium5	Dynamic programmingArray	No attempts yet	2s	512 MB	Judgeable
Root GameFor each N, decide who wins the subtraction game where a move subtracts any perfect square from a running total and taking the last square wins.	Medium5	Game theoryDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Restore the ArrayRecover grid A from grid B, where B is built by overlapping A with A shifted down X and right Y so overlapping cells are summed.	Medium5	MatrixSimulation+2	No attempts yet	2s	512 MB	Judgeable
Pipe Move 2Count the ways to push a 2-cell pipe (horizontal, vertical, or diagonal) across an N by N grid so its end reaches (N, N), keeping all covered cells empty.	Medium5	Dynamic programmingImplementation+2	No attempts yet	0.5s	512 MB	Judgeable
ContestGiven N intervals with start time, end time, and prize money, choose non-overlapping contests (end must not touch the next start) to maximize total prize.	Medium5	Dynamic programmingSorting+2	No attempts yet	1s	256 MB	Judgeable
Cowburger Kitchen WorkerWith M cheeseburgers and K fries available, pick the largest subset of orders, each requiring some of each item, that fits within both limits.	Medium5	Dynamic programmingGreedy+2	No attempts yet	3s	512 MB	Judgeable
Largest Sum Decreasing SubsequenceGiven a sequence, find a strictly decreasing subsequence with the maximum possible sum and print that sum.	Medium5	Dynamic programmingArray+2	No attempts yet	1s	256 MB	Judgeable
Making the Number NCount how many digit-by-digit sequences build the number N when each new digit is attached to the left or right end.	Medium5	Dynamic programmingString+2	No attempts yet	1s	256 MB	Judgeable
Being a Celebrity Is HardGiven a weighted undirected graph and two starting nodes, pick a meeting node minimizing the sum of both shortest distances and breaking ties by Jiheon's distance then index.	Medium5	Shortest pathGraph+1	No attempts yet	1s	256 MB	Judgeable
League of Legends (Large)Count the sequences of skills A (1 second) and B (M seconds) that fill exactly N seconds with no idle time, modulo 1e9+7.	Medium5	Dynamic programmingCombinatorics+1	No attempts yet	3s	256 MB	Judgeable
BackdoorFind the shortest travel time from junction 0 to junction N-1 in an undirected weighted graph, where every intermediate junction marked visible is blocked and only the Nexus may be entered.	Medium5	Shortest pathGraph+2	No attempts yet	2s	512 MB	Judgeable
FLEXDistribute M extra ten-thousand-won units among N days to minimize the sum of squared drops between consecutive daily spends.	Medium5	Dynamic programmingGreedy+2	No attempts yet	2s	512 MB	Judgeable
Promoting a ClubGiven a forest, choose the fewest vertices so that every vertex is either chosen or adjacent to a chosen one (minimum dominating set on a forest).	Medium5	TreeDynamic programming+2	No attempts yet	2s	256 MB	Judgeable
StringsBuild strings by concatenating earlier strings or slicing a substring, then output the sum of ASCII codes of the final string modulo 1e9+7, without materializing the possibly huge string.	Medium5	Dynamic programmingString+2	No attempts yet	2s	512 MB	Judgeable
Code WordCount length-l digit sequences on an r by c grid where no two consecutive presses are orthogonally or diagonally adjacent, mod 1e9+7.	Medium5	Dynamic programmingMatrix+2	No attempts yet	1s	512 MB	Judgeable
Four SquaresGiven n up to 50,000, print the minimum number of perfect squares whose sum equals n.	Medium5	Dynamic programmingMath+2	No attempts yet	0.5s	512 MB	Judgeable
Efficient ExchangeGiven a payment amount, minimize the total number of power-of-10 coins exchanged in both directions, allowing both sides to give change.	Medium5	Dynamic programmingGreedy+2	No attempts yet	3s	512 MB	Judgeable
What Does UNIST Stand For?Count ways to pick a prefix of each of N words so the concatenation spells UNIST, modulo 1e9+7.	Medium5	Dynamic programmingString+2	No attempts yet	1s	512 MB	Judgeable
Course SelectionChoose courses with given importance and study time so total time stays within N and total importance is maximized.	Medium5	Dynamic programmingArray+2	No attempts yet	1s	512 MB	Judgeable
Keyboards in ConcertGiven n keyboards, the sets of notes each can play, and the note sequence of a tune, find the minimum number of keyboard switches needed to play the whole tune.	Medium5	Dynamic programmingHash map+2	No attempts yet	1s	512 MB	Judgeable
SnowballSnowballs form at each altitude with size 1 and multiply by x each centimeter they descend; find the total size of all snowballs modulo 1e9+7.	Medium5	MathPrefix sum+2	No attempts yet	0.5s	256 MB	Judgeable
DessertEach day pick one of M desserts to maximize total satisfaction, where repeating the same dessert halves that day's value (rounded down).	Medium5	Dynamic programmingGreedy+2	No attempts yet	1s	256 MB	Judgeable
What's Mine is MinePick non-overlapping ore intervals to maximize total value, where each interval's value is its duration times its mineral's price.	Medium5	Dynamic programmingSorting+2	No attempts yet	0.5s	512 MB	Judgeable
HowlGiven a valid howl over A, H, O, W, construct a valid howl that is strictly longer, or report that none exists.	Medium5	StringGreedy+2	No attempts yet	1s	512 MB	Judgeable
Rainbow StringsCount subsequences of a string in which no letter repeats, distinguishing them by position, modulo 11092019.	Medium5	Dynamic programmingMath+2	No attempts yet	1s	512 MB	Judgeable
7-Segment DisplayUsing n seven-segment displays, each showing a digit 0-9 or the two-digit value 11, find the largest multiple of m displayable across the displays.	Medium5	Brute forceMath+2	No attempts yet	3s	1024 MB	Judgeable
Buying Ramen (Small)Buy exactly Ai packs from each factory using 1-pack, 2-pack, or 3-pack deals with different costs, minimizing total money.	Medium5	GreedyDynamic programming+2	No attempts yet	0.5s	32 MB	Judgeable
Stacking Blocks TogetherEach of N students offers a set of distinct block sizes, at most one block per student is used, and we count subsets of students whose chosen blocks sum to exactly H modulo 10007.	Medium5	Dynamic programmingPrefix sum+2	No attempts yet	1s	256 MB	Judgeable
Unstable SubstancesEach substance conflicts with exactly one other; choose a subset with no conflicting pair to maximize total weight.	Medium5	GraphDynamic programming+2	No attempts yet	1.2s	256 MB	Judgeable
A Really Odd SequenceGiven a sequence of integers, find the maximum sum of a contiguous subarray whose length is odd.	Medium5	ArrayDynamic programming+2	No attempts yet	6s	512 MB	Judgeable
Reversing StringsFor each string choose to reverse it or not so the sequence becomes lexicographically sorted, and output the lexicographically smallest such 0-1 choice string.	Medium5	GreedyString+2	No attempts yet	1s	256 MB	Judgeable
Meeting Room Scheduling 4Choose a set of non-overlapping meetings, where touching endpoints are allowed, to maximize the total number of attendees.	Medium5	Dynamic programmingSorting+2	No attempts yet	1s	256 MB	Judgeable
Painting ExchangeGiven who can sell to whom at what price, find the longest chain of distinct buyers starting from artist 1 where each resale price never drops below the purchase price.	Medium6	Dynamic programmingBit manipulation+2	No attempts yet	2s	128 MB	Judgeable
Park Seongwon's ProbabilityCount permutations of up to 15 numbers whose concatenation is divisible by K, and output the probability as a reduced fraction.	Medium6	Dynamic programmingBit manipulation+2	No attempts yet	2s	128 MB	Judgeable
Power PlantsGiven restart costs between plants and which plants are already on, find the minimum total cost to reach at least P working plants, or -1.	Medium6	Dynamic programmingBit manipulation+2	No attempts yet	2s	128 MB	Judgeable
Search EngineGiven directed links between websites, compute one website's trust score by summing scores of linking sites only when no cycle would result.	Medium6	GraphDFS+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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
Morning Three and Evening FourGiven N banana weights, choose non-overlapping length-K blocks to move as a C-second group, minimizing total time and then the number of groups used, with output of chosen block positions.	Medium6	Dynamic programmingPrefix sum+2	No attempts yet	2s	128 MB	Judgeable
Tiling a GridCount the ways to fully tile an N by M grid (N, M up to 14) with 2x1 dominoes, modulo 9901.	Medium6	Dynamic programmingBit manipulation+2	No attempts yet	2s	128 MB	Judgeable
XYZ StringGiven a self-similar X/Y/Z rewriting sequence, answer queries about the stage N string's length, its k-th character, or the count of a given character without building the full string.	Medium6	RecursionDivide and conquer+2	No attempts yet	2s	128 MB	Judgeable
Largest Zero SubmatrixGiven a binary matrix, find the maximum area rectangle of consecutive rows and columns that contains only zeros.	Medium6	StackDynamic programming+2	No attempts yet	2s	128 MB	Judgeable
CubeditorGiven a lowercase string of length up to 5000, find the maximum length of a substring that occurs at least twice, allowing overlapping occurrences.	Medium6	StringDynamic programming+1	No attempts yet	0.5s	128 MB	Judgeable
Tile CodesCount distinct tilings of a 2xN board using 1x2, 2x1, and 2x2 tiles, where mirror-image tilings under left-right flip count as one.	Medium6	Dynamic programmingCombinatorics+1	No attempts yet	2s	128 MB	Judgeable
Making CouplesGiven lists of men's and women's personality values, form min(n, m) man-woman couples that minimize the total absolute difference of matched values.	Medium6	Dynamic programmingSorting+2	No attempts yet	2s	128 MB	Judgeable
PibonacciCompute a Fibonacci-like sequence defined with the irrational constant pi as a recursive step and output it modulo 10^18.	Medium6	Dynamic programmingRecursion+1	No attempts yet	2s	128 MB	Judgeable
Maximum Submatrix SumGiven an N by M integer matrix, find the maximum possible sum over all contiguous rectangular submatrices.	Medium6	Dynamic programmingMatrix+2	No attempts yet	2s	128 MB	Judgeable