Problems
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Total results3,701 problems
| Title | Level | Topics | Solved | Time limit | Memory limit | Judge |
|---|---|---|---|---|---|---|
| Flipping El-fetieraEach of K operations picks a uniformly random rectangular submatrix and flips every cell in it; compute the expected number of cells holding 1 at the end. | Medium7 | ProbabilityDynamic programming+2 | No attempts yet | 10s | 512 MB | Judgeable |
| Fixing Open Source BugsGiven bugs with fun values and prerequisite dependencies, choose a set of bugs to fix (each with all its prerequisites) that maximizes total fun. | Medium7 | GraphDynamic programming+2 | No attempts yet | 4s | 256 MB | Judgeable |
| TimelineGiven lower bounds on each of N session dates and C constraints that one session is at least x days after another, find the earliest feasible date for every session. | Medium7 | GraphShortest path+2 | No attempts yet | 2s | 512 MB | Judgeable |
| New Year and PermutationCount over all n! permutations the total number of segments whose max minus min equals length minus one, modulo a prime m. | Medium7 | CombinatoricsMath+2 | No attempts yet | 1s | 1024 MB | Judgeable |
| Number Card Removal GameFor each N, cards 1..N are played by removing a card x together with x-1 and x+1; find who wins under perfect play. | Medium7 | Game theoryDynamic programming+2 | No attempts yet | 1s | 256 MB | Judgeable |
| Equal DigitsCount the ways to delete disjoint substrings of length over 1 whose first and last digits match, so the remaining non-empty string has all distinct digits. | Medium7 | Dynamic programmingCombinatorics+2 | No attempts yet | 3s | 256 MB | Judgeable |
| BalanceGiven an N x N matrix A, find the entrywise-minimal balanced matrix B (satisfying the additive rectangle condition) with B[i][j] >= A[i][j], and report its sum. | Medium7 | Dynamic programmingGreedy+2 | No attempts yet | 1s | 512 MB | Judgeable |
| Cube SummationFor each N, sum k^3 over all partitions of N with k parts, modulo 998244353, with up to 1e5 queries. | Medium7 | Dynamic programmingCombinatorics+2 | No attempts yet | 4s | 512 MB | Judgeable |
| Two PathsGiven a weighted undirected graph, find the shortest walk from node 1 to node n that differs from Alice's chosen shortest path. | Medium7 | GraphShortest path+2 | No attempts yet | 1s | 512 MB | Judgeable |
| DenominationsCount the number of ways to make change for n SmurfCoins using denominations 1, 5, 10, 25, modulo 10^9+7, where n can be as large as 10^18. | Medium7 | MathCombinatorics+1 | No attempts yet | 0.5s | 512 MB | Judgeable |
| Shortest Accepted WordParse a regular expression over a, b, c and $ into a tree, then compute the shortest lexicographically smallest string each node accepts. | Medium7 | Dynamic programmingString+2 | No attempts yet | 1s | 256 MB | Judgeable |
| DotA QualsGiven 2^n players and Idned ranked k-th, compute the expected number of rounds he survives when opponents are randomly paired each round and the higher rating always wins. | Medium7 | ProbabilityCombinatorics+2 | No attempts yet | 1s | 256 MB | Judgeable |
| Bin PackingGiven up to 24 item weights and a bin capacity S, find the minimum number of bins that hold all items with each bin's total weight at most S. | Medium7 | Dynamic programmingBit manipulation+2 | No attempts yet | 4s | 256 MB | Judgeable |
| Tree GameGiven a tree with all edges white, repeatedly pick a simple path whose endpoints are leaves and whose edges are all white, and paint those edges black; find the fewest paths needed to cover every edge. | Medium7 | TreeDFS+2 | No attempts yet | 1s | 512 MB | Judgeable |
| EquationCount integers n in [a,b] with k times the sum of squared digits of n equal to n, where a and b go up to 10^18. | Medium7 | Dynamic programmingMath+2 | No attempts yet | 1s | 256 MB | Judgeable |
| Geese vs. HawksMatch games of two teams so that every paired game's win/loss outcome agrees, maximizing the total points scored by both teams in the matched games. | Medium7 | Dynamic programmingString+2 | No attempts yet | 1s | 512 MB | Judgeable |
| RouteGiven trains with fixed departure and arrival times, find a route from station 1 to station n minimizing a quadratic cost on total waiting plus the final arrival time. | Medium7 | GraphShortest path+2 | No attempts yet | 1s | 512 MB | Judgeable |
| SafetyGiven N stack heights and a bound H, find the minimum number of unit additions/removals so that every adjacent pair differs by at most H. | Medium7 | Dynamic programmingSliding window+1 | No attempts yet | 1s | 512 MB | Judgeable |
| KnapsackBounded knapsack: given N item types with value, weight, and a large copy count, pick items within weight S to maximize total value. | Medium7 | Dynamic programmingGreedy+2 | No attempts yet | 1s | 512 MB | Judgeable |
| Cows DriveFor each city, find the minimum travel time from city 1 minus the taste value of one rest stop chosen on the path. | Medium7 | GraphShortest path+2 | No attempts yet | 0.5s | 1024 MB | Judgeable |
| Downloading EpisodesChoose one fixed sequence of byte requests so that all n episodes download with minimum total packet size, where each packet adds a fixed header k. | Medium7 | Dynamic programmingGreedy+2 | No attempts yet | 1s | 512 MB | Judgeable |
| DivisionChange the fewest digits of n so the resulting number has no leading zeros and is divisible by m, or report -1. | Medium7 | Dynamic programmingMath+2 | No attempts yet | 2s | 512 MB | Judgeable |
| Autumn ParkOn a grid with obstacles, count paths from entrance to exit whose length is exactly two more than the shortest path, modulo 1e9+9. | Medium7 | GraphBFS+2 | No attempts yet | 2s | 512 MB | Judgeable |
| Bridge ReinforcementGiven a graph with maximum degree 2, count the minimum-size edge subsets whose connectivity components match the original graph, modulo 1e9+7. | Medium7 | GraphCombinatorics+2 | No attempts yet | 2s | 512 MB | Judgeable |
| Hungry Frog BillyGiven sorted positions of midges on one side of a rock, eating a midge at distance d costs d energy and pushes all other midges one unit away from d, toward 0 or further out; find the minimum total energy to eat them all. | Medium7 | GreedyDynamic programming+1 | No attempts yet | 2s | 512 MB | Judgeable |
| Array InitializationCount ordered sequences of M interval marks on an array of length N whose union covers every position, modulo 1e9+7. | Medium7 | Dynamic programmingCombinatorics+2 | No attempts yet | 2s | 512 MB | Judgeable |
| School OlympiadAssign n students at given coordinates to three locations with capacity limits so the total walking distance is minimized. | Medium7 | GreedySorting+2 | No attempts yet | 1s | 512 MB | Judgeable |
| PrintingGiven n cartridge types with cost c_i and page yield p_i (both at most 200), find the minimum total cost to reach exactly k pages, or -1 if impossible. | Medium7 | Dynamic programmingNumber theory+2 | No attempts yet | 2s | 512 MB | Judgeable |
| School DemocracyPartition the classes into consecutive groups of size between l and r, and maximize the total difference between elected boys and girls, where each group elects the side with more votes or both on a tie. | Medium7 | Dynamic programmingPrefix sum+2 | No attempts yet | 2s | 512 MB | Judgeable |
| Interval TrainingCount sequences of positive integers starting at k, summing to n, whose adjacent comparisons strictly alternate up and down, modulo 1e9+7. | Medium7 | Dynamic programmingCombinatorics+2 | No attempts yet | 2s | 512 MB | Judgeable |
| Jedi AcademyGiven a DAG of skill prerequisites and two buildings, find the shortest total time to learn all skills, counting travel and learning time. | Medium7 | GraphDynamic programming+2 | No attempts yet | 2s | 512 MB | Judgeable |
| Diamond MineGiven an R by C grid of 0s and 1s, find the largest size of a diamond shape (a 45-degree rotated square outline) formed entirely of 1s. | Hard8 | Dynamic programmingBinary search+2 | No attempts yet | 0.75s | 128 MB | Judgeable |
| UnicornCount the number of paths on an N by M letter grid where a chess unicorn piece spells out a given word, modulo 1e9+7. | Hard8 | Dynamic programmingPrefix sum+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Palindrome SentencesGiven up to 13 distinct words, count ordered arrangements of a subset of them whose concatenation without spaces forms a palindrome. | Hard8 | Dynamic programmingBit manipulation+2 | No attempts yet | 2s | 128 MB | Judgeable |
| A-HansuCount N-digit numbers with nondecreasing digits whose minimum partition into consecutive arithmetic-progression blocks is exactly A, modulo 1e9+7. | Hard8 | CombinatoricsDynamic programming+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Jimin Kim's InvasionBlock every boundary-to-capital path on a grid using the fewest terrain cells, breaking ties by minimum total obstacle size. | Hard8 | GraphShortest path+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Sticker CollectionGiven N stickers with prices and values, some already owned, find the minimum starting money so that after selling and buying, the total value owned reaches at least K. | Hard8 | Dynamic programmingBit manipulation+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Paper FoldingGiven an N by M grid of integers, repeatedly fold it along row or column lines so overlapping cells sum, and find the maximum value obtainable in any cell. | Hard8 | Dynamic programmingIntervals+2 | No attempts yet | 2s | 128 MB | Judgeable |
| ShuffleCount song sequences (repeatable, with genre transition rules and per-song lengths 1 to 9) whose total play time lies in [A, B], modulo a prime. | Hard8 | Dynamic programmingMatrix+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Same TowersGiven up to 50 block heights summing to at most 500,000, find the maximum equal height achievable by two disjoint nonempty stacks, or report -1 if impossible. | Hard8 | Dynamic programmingArray+1 | No attempts yet | 2s | 512 MB | Judgeable |
| TteokgukPlace additional guards, subject to company office limits, so that the number of cooperation edges with exactly one guarded endpoint is minimized. | Hard8 | GraphMinimum spanning tree+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Fibonacci KnapsackPick items whose weights are Fibonacci numbers into a bag of capacity C to maximize total value, where N is at most 50 and all numbers fit in 64 bits. | Hard8 | Dynamic programmingGreedy+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Robot RaceGiven a grid with two robots and a shared command string, find the smallest starting position where robot Y is guaranteed to reach the target before robot F. | Hard8 | BFSGraph+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Minimum Cost Connected CellsGiven an N by M grid of integers with N, M at most 9, find the minimum total cost over all connected sets of cells (empty set allowed). | Hard8 | Dynamic programmingBit manipulation+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Toy SterilizationGiven daily toy demands over D days and two sterilization services with different delays and costs, decide which used toys to sterilize or discard versus buying new ones to minimize total cost. | Hard8 | GreedyGraph+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Increasing ListReplace every '?' in a string with a digit or comma to form the lexicographically smallest strictly increasing list of positive integers with no leading zeros, or print -1 if impossible. | Hard8 | BacktrackingGreedy+2 | No attempts yet | 2s | 128 MB | Judgeable |
| CoveringTile every X cell of a grid using unrotated 6-cell A pieces and 2-cell horizontal B pieces without overlap, printing the lexicographically smallest covering or -1 if impossible. | Hard8 | Dynamic programmingBacktracking+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Misheard BinaryCount distinct binary strings obtainable by shifting each bit of an N-bit number at most D positions, then output the K-th smallest such string. | Hard8 | Dynamic programmingCombinatorics+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Weather ForecastingChoose r horizontal and s vertical cut lines on an N x M grid to minimize the maximum sum of cell values inside any resulting rectangular section. | Hard8 | Binary searchDynamic programming+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Coin Passing GameGiven biased left/right passing probabilities on a circle of N students starting at student K, compute the probability that student N is the last student to first receive the coin. | Hard8 | ProbabilityDynamic programming+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Count Palindromic Word SequencesCount ordered sequences of given words, space-joined, whose concatenation (ignoring spaces) is a palindrome of length at most K, modulo a prime. | Hard8 | Dynamic programmingString matching+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Make a Monotone SequenceGiven N nonnegative integers, build a monotone (non-decreasing or non-increasing) sequence minimizing the total absolute difference from the original. | Hard8 | Dynamic programmingGreedy+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Boyle's LawCount positive integers N up to 10^18 whose self-product, N times the product of its digits, falls within a given range [A, B]. | Hard8 | MathDynamic programming+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Magic StoneGiven n, k, and i, find the i-th lexicographically smallest length-n I/X string with at most k differing adjacent pairs, treating a string and its reverse as identical. | Hard8 | CombinatoricsDynamic programming+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Rich Person's Coin ExchangeGiven a huge target amount M (up to 10^18) and up to 1000 coin denominations each at most 10000, find the minimum number of coins summing exactly to M. | Hard8 | Shortest pathGraph+2 | No attempts yet | 2s | 128 MB | Judgeable |
| P-SequencesCount permutations of a set of distinct integers where no two adjacent elements have a difference divisible by P, for two test cases, modulo 1234567891. | Hard8 | CombinatoricsDynamic programming+1 | No attempts yet | 2s | 256 MB | Judgeable |
| Cave ExplorationFind the minimum total time to move all explorers across a bridge to the exit side, given one shared map, a weight-limited bridge, and trust rules for group crossings. | Hard8 | Shortest pathBit manipulation+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Increasing SequenceSplit a digit string into pieces forming a strictly increasing sequence of numbers, minimizing the last value with tie-breaks favoring larger earlier numbers. | Hard8 | Dynamic programmingString+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Merge WordsGiven up to 12 uppercase words, find the shortest string containing all of them as substrings, breaking ties by lexicographic order. | Hard8 | Dynamic programmingBit manipulation+2 | No attempts yet | 5s | 128 MB | Judgeable |
| Increasing SequenceSplit a huge digit string into pieces forming a strictly increasing sequence of numbers, breaking ties by minimizing the last piece then maximizing earlier pieces, and output the product mod 1,000,000,003. | Hard8 | Dynamic programmingGreedy+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Protective TentsGiven non-overlapping horizontal tents, add horizontal segments above them so that every point of the interval between the leftmost and rightmost endpoints receives downward water. | Hard8 | GreedyIntervals+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Quiz ShowFor N ordered quiz questions, choose right or wrong answers to maximize score: correct answers earn coins and points, hitting M coins gives a bonus, wrong answers reset coins and cost points. | Hard8 | Dynamic programmingArray+2 | No attempts yet | 5s | 128 MB | Judgeable |
| NetworkCount non-isomorphic trees on N+1 nodes where one fixed hub node has any degree but every other node must have odd degree. | Hard8 | CombinatoricsTree+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Choosing GuitarsN guitars sit in a circle, and each turn the mover must take one guitar from every remaining contiguous group; find the max total value the first player can secure with optimal play. | Hard8 | Dynamic programmingGame theory+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Increasing Arcade PathsCount monotone grid paths from (1,1) to (N,M) grouped by how many arcades they visit, valid only if visited arcade numbers strictly increase. | Hard8 | Dynamic programmingCombinatorics+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Number ConcatenationGiven a subsequence left after deleting digits from the concatenation of 1,2,...,N, find the smallest N that could produce it. | Hard8 | String matchingBinary search+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Random SortCompute the expected number of random inversion swaps needed to sort a permutation of size at most 8 into increasing order. | Hard8 | ProbabilityDynamic programming+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Terminal CitiesGiven a connected graph with up to 15 cities, find a spanning tree that maximizes the number of vertices with degree exactly one. | Hard8 | Dynamic programmingBit manipulation+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Lucky-number SumGiven N, express it as a sum of numbers made only of digits 4 and 7, using the fewest terms and, among ties, the lexicographically smallest sequence. | Hard8 | Dynamic programmingGreedy+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Polygon Dissection CountGiven a convex N-gon, count the number of ways to cut it with non-crossing diagonals into exactly K polygons, modulo 1000000000, or report impossibility. | Hard8 | CombinatoricsDynamic programming+1 | No attempts yet | 2s | 128 MB | Judgeable |
| Expected Repaints for BallsGiven N colored balls, compute the expected number of random repaint operations needed until all balls share one color. | Hard8 | ProbabilityDynamic programming+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Chess PracticeGiven N queens on a board, players alternately shift a queen toward (0,0) using Wythoff-move rules, and the winner is decided by XOR-ing Grundy values via Sprague-Grundy theory. | Hard8 | Game theoryDynamic programming+1 | No attempts yet | 2s | 128 MB | Judgeable |
| Amazing MazeFind the minimum time to collect all treasures and reach the exit in a grid maze whose per-cell open door direction rotates clockwise every minute. | Hard8 | BFSBit manipulation+2 | No attempts yet | 5s | 512 MB | Judgeable |
| Monkey TowerCompute the minimum number of moves to solve a 4-peg Tower of Hanoi with up to one million disks, using the Frame-Stewart recurrence modulo 9901. | Hard8 | Dynamic programmingMath+2 | No attempts yet | 2s | 128 MB | Judgeable |
| DuelTwo players alternately mark empty cells on a strip, winning instantly by forming three consecutive marks, and the task is to decide if the first player can force a win and list all winning first moves. | Hard8 | Game theoryCombinatorics+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Minimum Pairing Cost for Two SetsGiven two sorted sets S and T, choose pairs (one element from each) so every element in both sets appears in some pair, minimizing the total sum of |a-b| over chosen pairs. | Hard8 | Dynamic programmingGreedy+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Complete Binary TreeGiven two same-height complete binary trees whose leaves carry a permutation of labels, find the largest label subset whose pairwise leaf distances match in both trees. | Hard8 | Dynamic programmingTree+2 | No attempts yet | 5s | 128 MB | Judgeable |
| Lattice Convex PolygonGiven a rectangle of size M by N, find the maximum number of vertices a convex lattice polygon can have while staying inside it. | Hard8 | GeometryDynamic programming+2 | No attempts yet | 2s | 128 MB | Judgeable |
| TaxiCount directed paths from intersection A to B in a one-way road DAG that pass through a given set of required intermediate intersections in any order. | Hard8 | GraphDynamic programming+2 | No attempts yet | 2s | 256 MB | Judgeable |
| Jang Hongjun the Tofu SellerGiven a grid of letter grades, tile it with non-overlapping 2x1 dominoes to maximize the sum of pairwise grade prices, leaving uncovered cells worth zero. | Hard8 | GraphShortest path+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Minimum-Cost Number Matching (Hard)Given sorted sets S and T, choose pairs (s,t) with cost |s-t| so every element of both sets appears in at least one pair, minimizing total cost, for sizes up to 500000. | Hard8 | Dynamic programmingGreedy+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Fence Escape Season IVGiven N horizontal fence segments Jimin must dodge by sidestepping to their endpoints, compute the minimum total horizontal movement to reach the exit below. | Hard8 | Dynamic programmingGreedy+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Feeding the PandaFind the longest sequence of bamboo groves with strictly increasing tastiness where consecutive Manhattan distance stays within the destination's bamboo count. | Hard8 | Dynamic programmingGeometry+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Marble SlabsFind the minimum wasted area when guillotine-cutting a rectangular slab into a set of allowed non-rotatable rectangle sizes. | Hard8 | Dynamic programmingDivide and conquer+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Card FlippingGiven an R by 16 grid of target flip states, find the minimum number of contiguous row or column flip operations to turn all cards from face up to the required pattern. | Hard8 | Dynamic programmingBit manipulation+2 | No attempts yet | 5s | 128 MB | Judgeable |
| HighwayGiven an undirected graph where each road has a toll and a travel time, count the distinct Pareto-optimal (toll, time) pairs achievable by routes between two given cities. | Hard8 | Shortest pathGraph+2 | No attempts yet | 2s | 128 MB | Judgeable |
| AlleywaysFind the maximum-value path from node 1 to node n in a directed weighted graph, or report -1 if the value can grow without bound due to a positive cycle on a valid path. | Hard8 | Shortest pathGraph+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Surprise Gift DeliveryGiven N delivery points on a line from a warehouse, find the minimum cost combining limited-capacity truck trips, per-stop parking fees, and one-at-a-time walking deliveries to drop a gift at every point. | Hard8 | Dynamic programmingGreedy+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Palindrome EncodingGiven a binary string, repeatedly delete the second half of any even-length palindromic substring and find the minimum length achievable. | Hard8 | Dynamic programmingString+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Banknotes for a New GameChoose K denominations starting at 1 won where each next one is 2, 3, 4, or 5 times the previous, to minimize the number of banknotes summing to N won. | Hard8 | Dynamic programmingMath+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Food Wrap AreaGiven N food items on a 2-row by B-column grid, cover every food cell using at most K axis-aligned rectangular wraps while minimizing the total wrap area. | Hard8 | Dynamic programmingGreedy+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Log TransportGiven a tree of villages flowing into a kingdom, choose k extra sawmill locations to minimize the total weight times distance cost of routing each village's logs to its nearest downstream mill. | Hard8 | Dynamic programmingTree+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Tree Height ReductionGiven a rooted tree and target height H, find the minimum total cost of repeatedly reattaching vertices to ancestors (cost based on level gap) to bring the tree height down to at most H. | Hard8 | TreeDynamic programming+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Broadcast NetworkPick which edges of a rooted tree to install so that total user fees minus installation cost stays non-negative while maximizing the number of served users, solved with tree knapsack DP. | Hard8 | Dynamic programmingTree+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Building a Tree ModelGiven a tree, find the minimum number of non-branching path segments (strings) needed to cover every edge exactly once, then minimize the length of the longest such string. | Hard8 | TreeDynamic programming+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Cave ExplorationFind the minimum-time simple cycle through room 1 in a directed graph built from asymmetric tunnel costs, using no room or tunnel twice. | Hard8 | GraphShortest path+1 | No attempts yet | 1s | 256 MB | Judgeable |
| SpiderwebGiven a convex polygon's vertices and circular puddles, find the maximum number of non-crossing diagonals that avoid all puddles. | Hard8 | Dynamic programmingGeometry+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Roof ConstructionGiven N points and a limit K, find the minimum vertical offset needed so a concave polyline with at most K segments lies on or above every point. | Hard8 | GeometryBinary search+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Clone RobotGiven a maze with a start and up to 250 keys, minimize the total moves of self-cloning robots (splitting only at start/key cells) needed to collect every key. | Hard8 | Shortest pathMinimum spanning tree+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Hotel ReservationAssign men, women, and married couples to rooms with capacity/cost constraints under strict cohabitation rules, minimizing total rental cost or reporting impossibility. | Hard8 | GreedyDynamic programming+1 | No attempts yet | 2s | 128 MB | Judgeable |