Interview core

Mediums from real onsites

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Total results3,612 problems

Shallow Bracket Sequences
Medium6
Dynamic programming, String
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Freight Train
Medium6
Two pointers, Binary search+1
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Clone Army
Medium6
Greedy, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Cukiernia
Medium6
Greedy, Brute force
No attempts yet
Time limit
14s
Memory limit
1024 MB
Judgeable
Debt Counter
Medium6
Segment tree, Implementation
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Binary Table
Medium6
Matrix, Prefix sum
No attempts yet
Time limit
6s
Memory limit
1024 MB
Judgeable
Transfers
Medium6
Dynamic programming, Bit manipulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Mountain Ranges
Medium6
Minimum spanning tree, Geometry+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Transmitters
Medium6
Tree, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Laser Chess
Medium6
BFS, Graph+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Train Stations
Medium6
Greedy, Sorting
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Book Reviewers
Medium6
Topological sort, Union-find+1
No attempts yet
Time limit
6s
Memory limit
1024 MB
Judgeable
Roller Coaster Queue
Medium6
Greedy, Segment tree+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Flower Symmetry
Medium6
Greedy, Array
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Navigation Nightmare
Medium6
Union-find, Graph
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Cow Pool
Medium6
Prefix sum, Brute force+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
The Tree
Medium6
Trie, Tree+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Gas Stations
Medium6
Greedy, Stack
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Relay
Medium6
Sorting, Dynamic programming
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Melons
Medium6
Greedy, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Coin Quiz
Medium6
Binary search, Sliding window+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Cleaning
Medium6
Sliding window, Segment tree+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Survey Relay
Medium6
Sorting, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Driver's Dilemma
Medium6
Graph, Shortest path+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Tree Cutting
Medium6
Tree, DFS+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Gym Badges
Medium6
Greedy, Sorting+1
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Oil Producing Nation
Medium6
Prefix sum, Sliding window+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Movie Night
Medium6
Graph, Topological sort+1
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Makima's Lunch Pick for Today
Medium6
Graph, BFS+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Hanbyeol, More Than Just Cute
Medium6
BFS, Graph+1
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
After the End Credits
Medium6
Sorting, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Movie Director Shom 4
Medium6
Dynamic programming, String+1
No attempts yet
Time limit
0.5s
Memory limit
1024 MB
Judgeable
Longest Unfriendly Subsequence
Medium6
Dynamic programming, Array+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sigma Sigma Sigma Sigma
Medium6
Combinatorics, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sum Over Zero
Medium6
Dynamic programming, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Yoga Class
Medium6
Graph, DFS
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Stone Arranging 2
Medium6
Stack, Hash map
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Advertisement 2
Medium6
Intervals, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Unique Ability
Medium6
Shortest path, Graph
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Mysterious Road Signs
Medium6
Sliding window, Two pointers+1
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Costume Change
Medium6
Graph, Matrix+1
No attempts yet
Time limit
15s
Memory limit
1024 MB
Judgeable
Cherry Blossom Ending
Medium6
Segment tree, Sorting+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Demon Realm Anam
Medium6
Shortest path, Graph+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Ribbon (Hard)
Medium6
Intervals, Sorting
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sanjini's Travel Plan
Medium6
Minimum spanning tree, Union-find+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Teleporter
Medium6
Shortest path, Graph
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Favorite Tree
Medium6
Tree, DFS+1
No attempts yet
Time limit
0.1s
Memory limit
1024 MB
Judgeable
TreeScript
Medium6
Tree, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Unite to Survive
Medium6
Hash map, Union-find+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Split Surveillance Zones
Medium6
Binary search, Greedy+1
No attempts yet
Time limit
1.5s
Memory limit
512 MB
Judgeable
Skate Practice
Medium6
Greedy, Stack+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Ant Nests on the Lawn
Medium6
Tree, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Olympics
Medium6
Greedy, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Freestyle Masonry
Medium6
Sorting, Array+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Gerrymandering
Medium6
Dynamic programming, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Lead or Butterfly
Medium6
Graph, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Polarizers
Medium6
Segment tree, Bit manipulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Exhibit Placement
Medium6
Sorting, Segment tree+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Alien Squids
Medium6
Stack, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Secure Prison
Medium6
Sorting, Array+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Secure Prison (Basic)
Medium6
Sorting, Binary search+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Final Confrontation
Medium6
Two pointers, Sliding window+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Robot Production
Medium6
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Bridges
Medium6
Graph, DFS+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Candy
Medium6
Dynamic programming, Array
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Shifting Boxes and a Caesar Cipher
Medium6
String, String matching+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Repairing an Array
Medium6
Array, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Bulk Purchase
Medium6
Binary search, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Food Supplies for the Expedition
Medium6
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Attacking Pairs
Medium6
Sliding window, Binary search+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Morty and the Password
Medium6
Greedy, Array
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Noise
Medium6
Greedy, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
New Fountain
Medium6
Heap, BFS+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
The Secret Room
Medium6
Dynamic programming, Binary search+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Typing Troubles
Medium6
Dynamic programming, String matching+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Catching the Joker
Medium6
Tree, DFS+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Building the Fence
Medium6
Dynamic programming, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Message Delivery
Medium6
Dynamic programming, String
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Breaking the Cipher
Medium6
Dynamic programming, Hash map+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Defense
Medium6
Binary search, Tree+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Football Fields
Medium6
String matching, Geometry
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Berland Football Union
Medium6
Tree, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Feed the Headcrab
Medium6
Math, Prefix sum
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Harry Potter and the Battle for Hogwarts
Medium6
Array, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Interview
Medium6
Dynamic programming, Array
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Complexity
Medium6
Matrix, Hash map
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Ministry of Truth
Medium6
Prefix sum, Binary search+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Journey
Medium6
Tree, Greedy
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Unit Founding Event
Medium6
Greedy, Queue+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Longest distinct segment queries
Medium6
Array, Binary search
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Professor Won has too many assignments
Medium6
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Bitwise Expression
Medium6
Segment tree, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Veenus
Medium6
Tree, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Side Network
Medium6
Tree, DFS+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
프로그래밍 동아리
Medium6
Segment tree, Heap+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Short message 4
Medium6
String, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Prisoners
Medium6
Graph, Geometry+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sorting
Medium6
Array, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Honest Worker
Medium6
Dynamic programming, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Slicing Trees and Checking Paths
Medium6
Tree, DFS
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Shallow Bracket SequencesGiven a correct bracket sequence and a limit H, find the fewest brackets to reverse so the sequence stays correct and its nesting depth is at most H.	Medium6	Dynamic programmingString	No attempts yet	1s	1024 MB	Judgeable
Freight TrainGiven Bitek's list as a subsequence of Bajtek's list, mark each wagon 1 if Bitek could have recorded it and 0 if he certainly missed it.	Medium6	Two pointersBinary search+1	No attempts yet	10s	1024 MB	Judgeable
Clone ArmyGiven n enemy robots, find the minimum hours to grow your army past n, where each scan costs a hours and each print costs b hours.	Medium6	GreedyMath+1	No attempts yet	1s	1024 MB	Judgeable
CukierniaGiven n display cases with counts of three pastry kinds, find the minimum number of pastries to move so every case holds one kind.	Medium6	GreedyBrute force	No attempts yet	14s	1024 MB	Judgeable
Debt CounterTwo big numbers get single-digit updates, and each query asks for one digit of their sum, with carries propagating across positions.	Medium6	Segment treeImplementation	No attempts yet	10s	1024 MB	Judgeable
Binary TableGiven a binary table and rectangle flips, report after each flip the fewest top-left rectangle flips needed to reset the table to all zeros.	Medium6	MatrixPrefix sum	No attempts yet	6s	1024 MB	Judgeable
TransfersGiven a debt matrix for N friends (N up to 16), find the fewest transfers that bring every friend's net balance to zero.	Medium6	Dynamic programmingBit manipulation	No attempts yet	1s	1024 MB	Judgeable
Mountain RangesGiven N cities and M lines that split the plane, find the minimum total number of line crossings needed to connect all cities with roads.	Medium6	Minimum spanning treeGeometry+1	No attempts yet	2s	1024 MB	Judgeable
TransmittersGiven a tree of chambers, find the fewest Wi-Fi transmitters so every tunnel is covered by a transmitter at an endpoint or two transmitters next to it.	Medium6	TreeDynamic programming+1	No attempts yet	2s	1024 MB	Judgeable
Laser ChessFind the first second when smoke, spreading one cell per second, blocks every mirror-bounced laser path from the attack piece to the king.	Medium6	BFSGraph+1	No attempts yet	2s	1024 MB	Judgeable
Train StationsGiven each station's boarding and alighting counts, find an order where nobody gets off more than the people already on board, or report that no order exists.	Medium6	GreedySorting	No attempts yet	2s	1024 MB	Judgeable
Book ReviewersAssign ratings from 1 to M to N books so that every <, =, or ≤ comparison holds, or report -1 if no assignment exists.	Medium6	Topological sortUnion-find+1	No attempts yet	6s	1024 MB	Judgeable
Roller Coaster QueueGiven a line of groups and a car that holds K people, find how many laps each group waits when later groups may board first to fill free seats.	Medium6	GreedySegment tree+1	No attempts yet	3s	1024 MB	Judgeable
Flower SymmetryGiven a row of N flowers with K varieties, find the fewest adjacent swaps needed to make the row symmetric.	Medium6	GreedyArray	No attempts yet	2s	1024 MB	Judgeable
Navigation NightmareGiven roads added one at a time on a grid map, answer the Manhattan distance between two farms using only the first I roads, or -1 if it is not yet known.	Medium6	Union-findGraph	No attempts yet	1s	1024 MB	Judgeable
Cow PoolFind the largest L-shaped pool, counted in gridpoints, that fits in a W by H forest without covering any of the N tree points.	Medium6	Prefix sumBrute force+1	No attempts yet	1s	1024 MB	Judgeable
The TreePaint whole subtrees of an infinite binary tree, where colors shift by one per left or right step, and report the current color of vertices given by root paths.	Medium6	TrieTree+2	No attempts yet	1s	1024 MB	Judgeable
Gas StationsGiven gas stations with positions and prices, a budget, and a tank capacity, find the farthest point the car can reach.	Medium6	GreedyStack	No attempts yet	1s	1024 MB	Judgeable
RelayChoose three distinct members and their running order to minimize the relay time, where each runner has a sprint time A and a baton time B.	Medium6	SortingDynamic programming	No attempts yet	1s	1024 MB	Judgeable
MelonsFor each start index x, count the boxes needed to pack melons x through N in order under limit L, and report the weight of the last box.	Medium6	GreedyPrefix sum+2	No attempts yet	1s	1024 MB	Judgeable
Coin QuizPick a threshold b that empties cells holding at most b coins so every k consecutive cells have at least m empty ones, maximizing leftover coins minus b.	Medium6	Binary searchSliding window+1	No attempts yet	1s	1024 MB	Judgeable
CleaningFor each window of K consecutive zones, visit them from highest to lowest priority and sum the moves between them. Output the minimum total.	Medium6	Sliding windowSegment tree+1	No attempts yet	2s	1024 MB	Judgeable
Survey RelayGiven each soldier's task count and each task's staffing need, decide whether every task can be filled under any possible survey answers.	Medium6	SortingMath	No attempts yet	1s	1024 MB	Judgeable
Driver's DilemmaFind the smallest maximum discomfort for a drive from district 1 to N within time T, where lowering a road's discomfort to D costs extra travel time.	Medium6	GraphShortest path+1	No attempts yet	1s	1024 MB	Judgeable
Tree CuttingGiven a tree, remove one edge and reconnect the two parts with a new edge so the diameter is as large as possible. Output that maximum diameter.	Medium6	TreeDFS+1	No attempts yet	3s	1024 MB	Judgeable
Gym BadgesGiven each gym's level gain X_i and level cap L_i, find the most gyms you can challenge when your level must be at most L_i before each fight.	Medium6	GreedySorting+1	No attempts yet	1.5s	1024 MB	Judgeable
Oil Producing NationPick a contiguous arc of districts on a circle that contains at least K threat districts, maximizing the sum of the A values.	Medium6	Prefix sumSliding window+1	No attempts yet	1s	512 MB	Judgeable
Movie NightCount the nonempty friend subsets where every invited friend's required companion is also invited, modulo 1e9+7.	Medium6	GraphTopological sort+1	No attempts yet	1.5s	1024 MB	Judgeable
Makima's Lunch Pick for TodayFind the restaurant that Power, Denji, and Aki can each reach by walks of the same length over one-way roads, minimizing that length, and print their walks.	Medium6	GraphBFS+1	No attempts yet	1s	1024 MB	Judgeable
Hanbyeol, More Than Just CuteFind the shortest path from school S to home H on a grid where you cannot step back to the previous cell and any three most recent cells sum to at most K.	Medium6	BFSGraph+1	No attempts yet	1.5s	1024 MB	Judgeable
After the End CreditsChoose K-1 of N candidates to join the hero Y so that one member's total skill difference to the rest of the party is minimized, then print that minimum.	Medium6	SortingPrefix sum+1	No attempts yet	1s	1024 MB	Judgeable
Movie Director Shom 4Given an apocalyptic number up to 10^18, find its position among all numbers that contain three consecutive 6s, in increasing order.	Medium6	Dynamic programmingString+1	No attempts yet	0.5s	1024 MB	Judgeable
Longest Unfriendly SubsequenceGiven a sequence, find the length of the longest subsequence where any two elements at distance at most 2 are different.	Medium6	Dynamic programmingArray+1	No attempts yet	1s	1024 MB	Judgeable
Sigma Sigma Sigma SigmaGiven N integers, compute the nested sigma sum of max(A_k, A_l) over all valid index ranges, modulo 998244353.	Medium6	CombinatoricsSorting+1	No attempts yet	1s	1024 MB	Judgeable
Sum Over ZeroChoose pairwise disjoint segments whose element sums are all non-negative, maximizing the total length of the chosen segments.	Medium6	Dynamic programmingPrefix sum+1	No attempts yet	1s	1024 MB	Judgeable
Yoga ClassDecide whether some set of movements covers each replacement pair and never includes both movements of a conflicting pair.	Medium6	GraphDFS	No attempts yet	2s	1024 MB	Judgeable
Stone Arranging 2Stones are placed one by one, and each new stone repaints the stones after the last one with its color. Output the final colors.	Medium6	StackHash map	No attempts yet	2s	1024 MB	Judgeable
Advertisement 2Given each resident's coordinate and influence power, find the fewest residents to donate copies to so that everyone ends up with a copy.	Medium6	IntervalsSorting+1	No attempts yet	2s	1024 MB	Judgeable
Unique AbilityFind the minimum time from city 1 to city N when each road needs a matching group ID and switching IDs costs the absolute difference.	Medium6	Shortest pathGraph	No attempts yet	2s	1024 MB	Judgeable
Mysterious Road SignsFind the longest contiguous run of signs where each sign matches one shared west-facing value or one shared east-facing value, and count such runs.	Medium6	Sliding windowTwo pointers+1	No attempts yet	10s	1024 MB	Judgeable
Costume ChangeGiven an N by N grid of signed costume values, find the fewest cells to recolor so that no costume value repeats within any row or column.	Medium6	GraphMatrix+1	No attempts yet	15s	1024 MB	Judgeable
Cherry Blossom EndingGiven N cherry trees with bloom periods over M days, find the longest run of adjacent trees blooming together on any day and how many days reach that length.	Medium6	Segment treeSorting+1	No attempts yet	3s	1024 MB	Judgeable
Demon Realm AnamFor each building, count the minimum-cost paths from building 1, printing -1 when a zero-cost cycle makes the count infinite.	Medium6	Shortest pathGraph+2	No attempts yet	2s	1024 MB	Judgeable
Ribbon (Hard)Given N ribbons with positions, lengths, and colors, find two ribbons of different colors whose reach intervals overlap, or report that none exist.	Medium6	IntervalsSorting	No attempts yet	1s	1024 MB	Judgeable
Sanjini's Travel PlanGiven a weighted connected graph, pick N-1 roads with maximum total length, then find the shortest walk from the start city that visits every city.	Medium6	Minimum spanning treeUnion-find+1	No attempts yet	1s	512 MB	Judgeable
TeleporterFind the round when Bi Taro minimizes and Biba Ko maximizes the time to reach room N from room 1, or -1 if the game never ends.	Medium6	Shortest pathGraph	No attempts yet	2s	1024 MB	Judgeable
Favorite TreeGiven two trees T1 and T2, decide whether T1 contains a connected subtree that is isomorphic to T2.	Medium6	TreeDFS+1	No attempts yet	0.1s	1024 MB	Judgeable
TreeScriptFind the fewest registers needed to build a rooted tree from its parent array, where a parent must stay in a register until its children are created.	Medium6	TreeDynamic programming+1	No attempts yet	1s	1024 MB	Judgeable
Unite to SurviveGiven N sets, process commands that merge set b into set a and empty set b, and print the size of a queried set.	Medium6	Hash mapUnion-find+1	No attempts yet	2s	1024 MB	Judgeable
Split Surveillance ZonesSplit N rooms on a corridor into M consecutive zones so that the largest total pairwise distance within any zone is as small as possible.	Medium6	Binary searchGreedy+1	No attempts yet	1.5s	512 MB	Judgeable
Skate PracticeGiven N speed limits, find the maximum sum of speeds when speed can rise freely but drops by at most 1 between consecutive points.	Medium6	GreedyStack+1	No attempts yet	2s	1024 MB	Judgeable
Ant Nests on the LawnGiven a tree of N rooms, count the room pairs where adding one tunnel between them keeps the maximum set of non-adjacent ants the same size.	Medium6	TreeDynamic programming+1	No attempts yet	2s	1024 MB	Judgeable
OlympicsFor each country, find its best possible rank under two ranking methods after K more events, each awarding one gold, silver, and bronze to different countries.	Medium6	GreedySorting+1	No attempts yet	2s	1024 MB	Judgeable
Freestyle MasonryGiven the current column heights of a w by h wall, decide whether the empty cells can be filled exactly with 2x1 bricks.	Medium6	SortingArray+1	No attempts yet	2s	1024 MB	Judgeable
GerrymanderingSplit the array into contiguous segments so that positive-sum segments outnumber negative-sum segments. Zero-sum segments do not count either way.	Medium6	Dynamic programmingPrefix sum+1	No attempts yet	1s	1024 MB	Judgeable
Lead or ButterflyCount the distinct butterfly subgraphs in a given graph, where a butterfly is a center vertex with two disjoint triangles and two pendant neighbors.	Medium6	GraphCombinatorics+1	No attempts yet	1s	1024 MB	Judgeable
PolarizersGiven a row of polarizers with angle updates, answer whether light entering one polarizer can pass through another polarizer further down the row.	Medium6	Segment treeBit manipulation	No attempts yet	1s	1024 MB	Judgeable
Exhibit PlacementCount the distinct sets of exactly n exhibits that equal all exhibits with height at most H and width at most W for some H and W.	Medium6	SortingSegment tree+1	No attempts yet	1s	1024 MB	Judgeable
Alien SquidsGiven n columns of squids, find the minimum number of operations that remove x squids from a run of equal-height adjacent columns until all columns are empty.	Medium6	StackImplementation	No attempts yet	1s	1024 MB	Judgeable
Secure PrisonFor each room type i, find the minimum cost to enlarge another type j so that a type i room fits inside it.	Medium6	SortingArray+1	No attempts yet	2s	1024 MB	Judgeable
Secure Prison (Basic)Given n room types where none fits inside another, for each type i find the least cost of enlarging some other type j so that type i fits inside it.	Medium6	SortingBinary search+1	No attempts yet	2s	1024 MB	Judgeable
Final ConfrontationCount the consecutive wave groups whose segment intersection length is between m1 and m2 inclusive.	Medium6	Two pointersSliding window+1	No attempts yet	1s	1024 MB	Judgeable
Robot ProductionGiven resource costs for n machines, pair them so the total saving, floor((a_i+a_j)/100) per pair plus single savings, is maximized, using the fewest pairs.	Medium6	GreedySorting+1	No attempts yet	1s	1024 MB	Judgeable
BridgesGiven a connected graph, find the fewest extra edges needed so that no edge is a bridge anymore.	Medium6	GraphDFS+1	No attempts yet	2s	1024 MB	Judgeable
CandyFind the fewest adjacent swaps needed to make the first F boxes hold at least T candy in total, or report NO if that is impossible.	Medium6	Dynamic programmingArray	No attempts yet	3s	1024 MB	Judgeable
Shifting Boxes and a Caesar CipherFind a cyclic shift k and a Caesar shift d that turn string s into string t, or report that no such pair exists.	Medium6	StringString matching+1	No attempts yet	2s	1024 MB	Judgeable
Repairing an ArrayGiven an array, find the fewest moves of single elements to the front or back needed to sort it.	Medium6	ArraySorting+1	No attempts yet	2s	1024 MB	Judgeable
Bulk PurchasePick exactly m weapons using at least k distinct kinds to maximize total power, then minimize the largest count of any single kind.	Medium6	Binary searchSorting+1	No attempts yet	2s	1024 MB	Judgeable
Food Supplies for the ExpeditionPick the largest set of food types that can be fully eaten by their deadlines when c members eat c portions per day.	Medium6	GreedySorting+1	No attempts yet	1s	1024 MB	Judgeable
Attacking PairsGiven n strengths, find any pair of creatures within index distance k whose strength difference lies in [l, r], or report -1 -1 if none exists.	Medium6	Sliding windowBinary search+1	No attempts yet	2s	1024 MB	Judgeable
Morty and the PasswordGiven a permutation where each cup can be touched at most twice by adjacent swaps, output the lexicographically largest permutation reachable.	Medium6	GreedyArray	No attempts yet	2s	1024 MB	Judgeable
NoiseGiven noisy values and a noise bound R, find the most distinct values the original sequence could have, plus one valid original sequence.	Medium6	GreedySorting+1	No attempts yet	2s	1024 MB	Judgeable
New FountainGiven an n by m grid of pillar heights, find the maximum total volume of water the grid can hold without draining off the border.	Medium6	HeapBFS+1	No attempts yet	2s	1024 MB	Judgeable
The Secret RoomGiven a sequence, find the length of the longest subsequence where every pair satisfies a_i - a_j < j - i.	Medium6	Dynamic programmingBinary search+1	No attempts yet	2s	1024 MB	Judgeable
Typing TroublesGiven strings s and t of length n up to 5000, decide whether t can be formed by splitting s into blocks and placing each block at the front of the typed text.	Medium6	Dynamic programmingString matching+1	No attempts yet	1s	1024 MB	Judgeable
Catching the JokerGiven a tree and m paths, find the vertex from which the most paths can be walked as one simple route through every vertex on the path.	Medium6	TreeDFS+1	No attempts yet	2s	1024 MB	Judgeable
Building the FenceCount the subsets of boards that can form a polygon with nonzero area, meaning the longest board is shorter than the sum of the rest, modulo 1e9+7.	Medium6	Dynamic programmingSorting+1	No attempts yet	2s	1024 MB	Judgeable
Message DeliveryGiven k and a string s, find the longest substring that becomes a palindrome after deleting at most k characters, and print its endpoints.	Medium6	Dynamic programmingString	No attempts yet	2s	1024 MB	Judgeable
Breaking the CipherGiven a sequence of n numbers, find the sum over all subsegments of the count of distinct subsequences (empty included), modulo 1000000007.	Medium6	Dynamic programmingHash map+1	No attempts yet	2s	1024 MB	Judgeable
DefenseGiven a tree of k portals, pick n of them so the smallest pairwise distance is as large as possible, then print that distance.	Medium6	Binary searchTree+1	No attempts yet	2s	1024 MB	Judgeable
Football FieldsGiven two convex polygons, decide whether one can be mapped onto the other using translations and the eight symmetries generated by axis and diagonal reflections.	Medium6	String matchingGeometry	No attempts yet	2s	1024 MB	Judgeable
Berland Football UnionGiven a weighted tree, find every vertex where the sum of squared distances to all other vertices is minimal.	Medium6	TreeDynamic programming+1	No attempts yet	2s	1024 MB	Judgeable
Feed the HeadcrabGiven a multiset of group sizes that changes over time, each query n asks for the sum of n mod k over all groups k in the multiset.	Medium6	MathPrefix sum	No attempts yet	3s	1024 MB	Judgeable
Harry Potter and the Battle for HogwartsApply k passes of bubble sort to a permutation of 1 to n and print the array after those passes.	Medium6	ArrayImplementation	No attempts yet	2s	1024 MB	Judgeable
InterviewGiven two sequences a and b, find the length of the longest subsequence of a that is strictly increasing and also a subsequence of b.	Medium6	Dynamic programmingArray	No attempts yet	2s	1024 MB	Judgeable
ComplexityCount the unordered pairs of k by k subgrids that are not similar, where similar means one becomes the other after flipping whole rows or columns.	Medium6	MatrixHash map	No attempts yet	2s	1024 MB	Judgeable
Ministry of TruthSplit n issues into three contiguous, non-empty parts so that the gap between the largest and smallest part sums is as small as possible.	Medium6	Prefix sumBinary search+1	No attempts yet	2s	1024 MB	Judgeable
JourneyGiven a tree of n cities, find the fewest new roads to add so that a route visits every city once and returns to the capital.	Medium6	TreeGreedy	No attempts yet	2s	1024 MB	Judgeable
Unit Founding EventOrder N stages so each soldier joins its first preferred stage in that order and every stage meets its minimum headcount, or report -1.	Medium6	GreedyQueue+1	No attempts yet	1s	1024 MB	Judgeable
Longest distinct segment queriesGiven a sequence of N values and Q queries (l, r), find the length of the longest contiguous subarray inside [l, r] whose values are all distinct.	Medium6	ArrayBinary search	No attempts yet	1s	1024 MB	Judgeable
Professor Won has too many assignmentsChoose assignments that each start on a distinct day and finish by their deadline, and find the fewest bots needed to reach total points C.	Medium6	GreedySorting+1	No attempts yet	1s	1024 MB	Judgeable
Bitwise ExpressionStarting from 0, apply a list of AND, OR, and XOR operations left to right, and print the final value after each of Q single-operation replacements.	Medium6	Segment treeBit manipulation+1	No attempts yet	2s	1024 MB	Judgeable
VeenusGiven a rooted tree and a stream of toggles on node danger levels, report the lowest common ancestor of all currently high-danger nodes after each toggle.	Medium6	TreeSorting+1	No attempts yet	1s	1024 MB	Judgeable
Side NetworkGiven a tree of N servers, remove two servers and find the maximum (T=1) or minimum (T=2) sum of squared component sizes.	Medium6	TreeDFS+1	No attempts yet	3s	1024 MB	Judgeable
프로그래밍 동아리Given each member's attendance interval, output the problem solved each week: the smallest number no attending member has solved yet.	Medium6	Segment treeHeap+1	No attempts yet	1s	1024 MB	Judgeable
Short message 4Build the shortest lowercase string that contains every given planet name as a substring.	Medium6	StringDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
PrisonersFind the fewest guards to remove so that a path from the west wall to the east wall keeps more than 100 meters from every guard.	Medium6	GraphGeometry+1	No attempts yet	1s	1024 MB	Judgeable
SortingGiven a sequence of N integers, find the minimum number of contiguous blocks that can be reordered as whole blocks to produce a sorted sequence.	Medium6	ArrayGreedy+1	No attempts yet	1s	1024 MB	Judgeable
Honest WorkerChoose non-overlapping contractor jobs, each optionally quit early, to maximize total pay minus fake cover letter costs.	Medium6	Dynamic programmingSorting+1	No attempts yet	1s	1024 MB	Judgeable
Slicing Trees and Checking PathsGiven a tree, for each query remove the edges on the path from a to b and report whether c and d are still connected.	Medium6	TreeDFS	No attempts yet	4s	1024 MB	Judgeable