Interview core

Mediums from real onsites

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Total results3,617 problems

Monty's Hall
Medium5
Probability, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Efficient Bus Routing
Medium5
Tree, Greedy+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Bar Classification
Medium5
Matrix, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Bike Party
Medium5
Prefix sum, Array+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Scenery 2
Medium5
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
SHOW ME THE DUNGEON
Medium5
Dynamic programming, Sorting+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cutting the Long Cake
Medium5
Combinatorics, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Ball Draw Guessing Game
Medium5
Greedy, Sorting+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Deletive Editing
Medium5
String, Implementation
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Heroes of Might
Medium5
Greedy, Heap+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Strange Switches
Medium5
BFS, Bit manipulation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Club federation tournament for the national university programming contest
Medium5
Tree, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Abracadabra
Medium5
Array, Simulation+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Chalk Thief
Medium5
Union-find, Sorting+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
No-Edge Pizza
Medium5
Hash map, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Stimulant
Medium5
Prefix sum, Sorting+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Team Contest
Medium5
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Ravnica
Medium5
Tree, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Croats
Medium5
Tree, DFS+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Pikule
Medium5
Greedy, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sum
Medium5
Dynamic programming, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Arithmetic or geometric sequence?
Medium5
Array, Hash map+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Pikulice
Medium5
BFS, Graph+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Matchsticks
Medium5
Implementation, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Predicting the grass
Medium5
BFS, Graph+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Zigzag Subarrays
Medium5
Array, Dynamic programming
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Hangman 2
Medium5
Hash map, String+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Broken Communication Towers
Medium5
Shortest path, Graph+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Balloon Darts
Medium5
Union-find, Implementation
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
86 Eighty-Six 1
Medium5
Dynamic programming, BFS+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Cat Can Schedule
Medium5
Dynamic programming, Brute force
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Hacker Lee Dong-sik
Medium5
Binary search, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Power Dwelling in 3
Medium5
Tree, DFS+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Knock Down Dominoes
Medium5
Dynamic programming, Array
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Free Pass
Medium5
Greedy, Math
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Fire Truck
Medium5
Graph, Shortest path+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Carousel
Medium5
Prefix sum, Array+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Tree and Path Count Queries
Medium5
Tree, DFS+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Bracket-and-bar Sequences
Medium5
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Good Node Set Search
Medium5
Tree, Dynamic programming
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Fast Random Number Search
Medium5
BFS, Dynamic programming+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Fast Random Number Search
Medium5
Dynamic programming, Shortest path+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Harvest the most apples from k tree nodes
Medium5
Dynamic programming, Tree+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Wheel String
Medium5
Dynamic programming, Simulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Meeting Plaza
Medium5
Prefix sum, Brute force
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Set and Sequence and Query
Medium5
Intervals, Hash map+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Crossing the Field
Medium5
Dynamic programming, Array
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Barn Construction
Medium5
Stack, Matrix+1
No attempts yet
Time limit
1.5s
Memory limit
512 MB
Judgeable
RCV Simplification
Medium5
Sorting, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Panda Hunting Treasure Box
Medium5
Shortest path, Graph+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Lecture Allocation
Medium5
Dynamic programming
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Splitting Chocolate After One Bite
Medium5
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Tutorial Groupings
Medium5
Dynamic programming, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Ultimate Commitment Forever
Medium5
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
2D Array Multi-Update Single Sum
Medium5
Prefix sum, Matrix+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Food Display Arrangement
Medium5
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
x
Medium5
Geometry, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Hidden Message
Medium5
Dynamic programming, String
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Make the team
Medium5
Graph, Binary search
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Wedding DJ
Medium5
Intervals, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Gone Fishing
Medium5
Geometry, Brute force
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Team Shirts/Jerseys
Medium5
Backtracking, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Rotating Cards
Medium5
Greedy, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Jedi and the Galactic Empire
Medium5
Dynamic programming, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Rising Tides
Medium5
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Choosing the Gateway
Medium5
Bit manipulation, Tree+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Lost Edge
Medium5
BFS, Heap+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Lightbulbs
Medium5
Dynamic programming, Probability
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Longest Path
Medium5
Graph, Sorting
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Gift Discount
Medium5
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Islands Tour
Medium5
Graph, DFS+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Temporal Graph
Medium5
Dynamic programming, Graph+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sunwoo's Setlist
Medium5
Dynamic programming, Math
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Staircase Building (Small)
Medium5
Dynamic programming, Array
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hyundai Mobis Autonomous Driving System
Medium5
BFS, Shortest path+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Domino Toppling
Medium5
Stack, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Harvesting apples and pears from k tree nodes
Medium5
Dynamic programming, Tree
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Knitting Patterns
Medium5
Dynamic programming, String
No attempts yet
Time limit
3s
Memory limit
2048 MB
Judgeable
Kiosk Installation
Medium5
Graph, BFS+1
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Coffee Cup Combo
Medium5
Dynamic programming, Greedy
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Patio
Medium5
String, Prefix sum+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Gomgomi and the Cafeteria
Medium5
Greedy, Math+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Circus Knight
Medium5
Math, Union-find+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Gomgom and the Tournament
Medium5
Combinatorics, Probability+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Mathematical Lowest Common Ancestor
Medium5
Number theory, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Forbidden Turns
Medium5
Shortest path, Graph+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Data Centers
Medium5
Sorting, Simulation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Alien Invader Yooni
Medium5
Sorting, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Two Roads
Medium5
Shortest path, Graph
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Splitstream
Medium5
Recursion, Simulation+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Eating Apples Quickly
Medium5
Backtracking, Brute force
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Brothers in Arms
Medium5
Shortest path, Graph
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Interview Question
Medium5
Number theory, Brute force+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Justice Served
Medium5
Sorting, Dynamic programming
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Deforestation
Medium5
Greedy, Tree+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Permutations
Medium5
Array, Binary search+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Cutting with Lasers
Medium5
BFS, Matrix+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Eliminating Balloons
Medium5
Greedy, Array
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Geometry of Triangles
Medium5
Dynamic programming, Tree+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Helping the Transit
Medium5
Graph, DFS+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Monty's HallPick s of d doors, let Monty open e empty doors, then pick s doors again; find the maximum probability of winning.	Medium5	ProbabilityMath+1	No attempts yet	1s	1024 MB	Judgeable
Efficient Bus RoutingGiven a tree of N cities, cover every road with the fewest bus paths and print the two end stops of each path.	Medium5	TreeGreedy+1	No attempts yet	5s	1024 MB	Judgeable
Bar ClassificationGiven an N by N binary grid built from one all-ones row or column with up to N flipped cells, decide whether the bar is vertical, horizontal, or ambiguous.	Medium5	MatrixImplementation	No attempts yet	1s	1024 MB	Judgeable
Bike PartyGiven N circular parties with alcohol gains and bike distances, find a start party where the alcohol level stays above zero until Robin returns to the start.	Medium5	Prefix sumArray+1	No attempts yet	1s	1024 MB	Judgeable
Scenery 2Given n photo windows [a, b] that each need t time units, decide whether all n photographs can be taken without overlapping.	Medium5	GreedySorting+1	No attempts yet	1s	1024 MB	Judgeable
SHOW ME THE DUNGEONPick monsters and a fighting order so the total health spent stays within K, maximizing the residents freed.	Medium5	Dynamic programmingSorting+1	No attempts yet	2s	512 MB	Judgeable
Cutting the Long CakeCount the ways to make k-1 cuts in a cake of n cells so that every piece has the same number of toppings, modulo 1e9+7.	Medium5	CombinatoricsMath+1	No attempts yet	2s	512 MB	Judgeable
Ball Draw Guessing GameFor each number, choose the probability p_i of answering red so that the blue-bag error stays at most q while the red-bag error is minimized.	Medium5	GreedySorting+1	No attempts yet	3s	1024 MB	Judgeable
Deletive EditingGiven words s and t, decide whether t can be reached from s by repeatedly deleting the first occurrence of a called letter.	Medium5	StringImplementation	No attempts yet	3s	512 MB	Judgeable
Heroes of MightFind the least dragon health that lets the dragon destroy all peasant groups when it hits one group for d damage per round.	Medium5	GreedyHeap+1	No attempts yet	3s	512 MB	Judgeable
Strange SwitchesFind the fewest presses of off switches needed to turn every switch on, where each press flips the switches it is wired to.	Medium5	BFSBit manipulation	No attempts yet	2s	1024 MB	Judgeable
Club federation tournament for the national university programming contestGiven a single-elimination record with one match missing, find every match result that would complete a valid bracket.	Medium5	TreeImplementation	No attempts yet	2s	1024 MB	Judgeable
AbracadabraGiven a deck of N cards and a fixed modified riffle shuffle, answer Q queries for the card at position i after t shuffles.	Medium5	ArraySimulation+1	No attempts yet	3s	512 MB	Judgeable
Chalk ThiefPick a connected set of classrooms in a tree and steal the same amount from each, capped by the smallest chalk count in the set. Find the maximum total.	Medium5	Union-findSorting+1	No attempts yet	1s	512 MB	Judgeable
No-Edge PizzaTrack toppings on a circle of N slices; for each order, report whether every residue class mod l has one flavor and the minimum l-window sum.	Medium5	Hash mapMath+1	No attempts yet	1s	512 MB	Judgeable
StimulantGiven daily study and gaming hours and K stimulants that double the effect from their day on, find the maximum total skill with at most one stimulant per day.	Medium5	Prefix sumSorting+1	No attempts yet	10s	512 MB	Judgeable
Team ContestGiven N programmers with skill levels from 1 to 10, find the maximum number of disjoint triples whose minimum plus maximum skill exceeds K.	Medium5	GreedySorting+1	No attempts yet	1s	1024 MB	Judgeable
RavnicaGiven a tree of N cities, find the fewest roads to remove so that every city has at most two roads left.	Medium5	TreeDynamic programming+1	No attempts yet	1s	1024 MB	Judgeable
CroatsEach known Croat makes all of their descendants Croats, so after each new tip the task asks for the total number of people who are certainly Croats.	Medium5	TreeDFS+1	No attempts yet	1s	1024 MB	Judgeable
PikuleGiven N integers, find the largest value the last pikule can keep after N-1 pushes, and print a push order that reaches it.	Medium5	GreedyMath+1	No attempts yet	1s	1024 MB	Judgeable
SumGiven digit counts X and Y and a sum Z, count the unordered pairs of integers A and B with X and Y digits that add up to Z.	Medium5	Dynamic programmingMath	No attempts yet	1s	1024 MB	Judgeable
Arithmetic or geometric sequence?After each point update to an array of N values, report whether it is a positive arithmetic sequence (+), a positive geometric sequence (*), or neither (?).	Medium5	ArrayHash map+2	No attempts yet	2s	1024 MB	Judgeable
PikuliceFind the minimum number of slide and jump moves that turn a row of red and blue marbles with one empty stand into all reds, then the empty stand, then all blues.	Medium5	BFSGraph+1	No attempts yet	1s	1024 MB	Judgeable
MatchsticksCount the rectangles whose four sides are fully covered by matchsticks in an N by M grid where corners sit on odd rows and columns.	Medium5	ImplementationPrefix sum+1	No attempts yet	1s	1024 MB	Judgeable
Predicting the grassGiven the current and predicted grass grids and a spread range D, decide whether grass can spread from the current cells to exactly the predicted cells.	Medium5	BFSGraph+1	No attempts yet	2s	1024 MB	Judgeable
Zigzag SubarraysFor each test case, count the contiguous subarrays of length at least 2 whose adjacent elements strictly alternate between rising and falling.	Medium5	ArrayDynamic programming	No attempts yet	1s	512 MB	Judgeable
Hangman 2Given N distinct words of equal length, find each word that can be reached from another word by changing at most two letters.	Medium5	Hash mapString+1	No attempts yet	2s	1024 MB	Judgeable
Broken Communication TowersGiven two tower identifiers a and b, find the minimum-cost divisor-relation path between them, breaking ties by the smallest sum of identifiers on the path.	Medium5	Shortest pathGraph+1	No attempts yet	1s	512 MB	Judgeable
Balloon DartsGiven balloon scores and a burst order, find the highest segment score recorded at any point while the balloons are burst.	Medium5	Union-findImplementation	No attempts yet	1s	512 MB	Judgeable
86 Eighty-Six 1Given Legion positions on an N by N grid, find the minimum diagonal-move time for Shinei to reach every Legion, or report that it is impossible.	Medium5	Dynamic programmingBFS+1	No attempts yet	1s	1024 MB	Judgeable
Cat Can ScheduleGiven N kinds of cans with limited counts, assign one can to each cat on each of K days to maximize the total satisfaction of both cats.	Medium5	Dynamic programmingBrute force	No attempts yet	1s	512 MB	Judgeable
Hacker Lee Dong-sikFind the smallest possible maximum cost among accepted requests, so that every K consecutive requests includes at least one accepted request.	Medium5	Binary searchDynamic programming+1	No attempts yet	1s	512 MB	Judgeable
Power Dwelling in 3Split a tree of N stations into N/3 connected groups of three stations each, or report that no such split exists.	Medium5	TreeDFS+1	No attempts yet	2s	1024 MB	Judgeable
Knock Down DominoesGiven N domino weights, find the largest number of dominoes you can keep in order so that each one weighs no more than the total of all kept dominoes before it.	Medium5	Dynamic programmingArray	No attempts yet	1s	512 MB	Judgeable
Free PassGiven a usage limit for each ride type, find the maximum number of rides you can take without riding the same ride twice in a row.	Medium5	GreedyMath	No attempts yet	1s	512 MB	Judgeable
Fire TruckFind the shortest distance from station S to fire site T, and among all shortest paths, the most water the truck can have on arrival at T.	Medium5	GraphShortest path+1	No attempts yet	2s	512 MB	Judgeable
CarouselGiven N horses on a circle with a_i people on horse i, find the minimum number of moves to adjacent horses so every horse ends with exactly one person.	Medium5	Prefix sumArray+1	No attempts yet	1s	512 MB	Judgeable
Tree and Path Count QueriesGiven a tree with red and blue vertices, count for each query vertex u the red-blue simple paths that have u strictly inside them.	Medium5	TreeDFS+1	No attempts yet	1s	512 MB	Judgeable
Bracket-and-bar SequencesDefine a bijection between regular bracket-and-bar sequences of a given length and integers, then implement it in both directions.	Medium5	CombinatoricsDynamic programming+1	No attempts yet	2s	1024 MB	Judgeable
Good Node Set SearchPick nodes of a tree so that no two are adjacent and every unpicked internal node has a picked child, maximizing the total value.	Medium5	TreeDynamic programming	No attempts yet	1s	512 MB	Judgeable
Fast Random Number SearchFind the fewest moves on a 5 by 5 grid, avoiding -1 cells, to visit the cells labeled 1 through 6 starting from a given cell.	Medium5	BFSDynamic programming+1	No attempts yet	3s	512 MB	Judgeable
Fast Random Number SearchFind the fewest walk or run moves from the start cell needed to visit every cell numbered 1 through 6 in any order on a 5 x 5 board.	Medium5	Dynamic programmingShortest path+2	No attempts yet	3s	512 MB	Judgeable
Harvest the most apples from k tree nodesFind the most apples you can collect by choosing a connected set of at most k nodes that includes root 0.	Medium5	Dynamic programmingTree+1	No attempts yet	3s	512 MB	Judgeable
Wheel StringGiven a cyclic wheel of lowercase letters, find the fewest turns needed to build string S by appending letters, or report -1 if impossible.	Medium5	Dynamic programmingSimulation	No attempts yet	1s	1024 MB	Judgeable
Meeting PlazaGiven an N by M grid of values, pick two rows and two columns to form four paths and find the maximum of the enclosed green cell count plus the sum of the path cells.	Medium5	Prefix sumBrute force	No attempts yet	1s	1024 MB	Judgeable
Set and Sequence and QueryMaintain the count of distinct continuous increasing sequences in a set of integers under insertions and deletions, printing the count after each move.	Medium5	IntervalsHash map+1	No attempts yet	2s	1024 MB	Judgeable
Crossing the FieldPick a subsequence of flowers to maximize the sum of squared differences between adjacent picked beauty values.	Medium5	Dynamic programmingArray	No attempts yet	1s	512 MB	Judgeable
Barn ConstructionGiven a grid with obstacles, the task is to answer for each query (a, b) whether an empty rectangle of a rows and b columns exists.	Medium5	StackMatrix+1	No attempts yet	1.5s	512 MB	Judgeable
RCV SimplificationGiven each candidate's first-choice vote count in a ranked-choice election, find the candidates who cannot win under any possible second-choice ordering.	Medium5	SortingPrefix sum+2	No attempts yet	1s	1024 MB	Judgeable
Panda Hunting Treasure BoxFind the largest treasure box value Panda can reach with his starting energy, where entering a box cell ends the walk.	Medium5	Shortest pathGraph+1	No attempts yet	1s	1024 MB	Judgeable
Lecture AllocationChoose how many lectures (0 to 3) each teacher gives so that exactly L lectures are covered at the lowest total cost.	Medium5	Dynamic programming	No attempts yet	1s	1024 MB	Judgeable
Splitting Chocolate After One BiteCount the domino tilings of a 3 by N block with one cell removed, answering up to 1e5 queries modulo 1e9+7.	Medium5	Dynamic programmingBit manipulation+1	No attempts yet	1s	1024 MB	Judgeable
Tutorial GroupingsCount the ways to split students by knowledge level into ordered groups with level span at most k and size at most s, modulo 1e9+7.	Medium5	Dynamic programmingSorting+1	No attempts yet	1s	1024 MB	Judgeable
Ultimate Commitment ForeverFor each trip, count the shortest grid paths from start to end that avoid up to 10 construction points, modulo 10^9+7.	Medium5	CombinatoricsDynamic programming+1	No attempts yet	1s	1024 MB	Judgeable
2D Array Multi-Update Single SumGiven an n by n grid and a list of rectangle add and rectangle sum queries, print the one final rectangle sum after all updates are applied.	Medium5	Prefix sumMatrix+1	No attempts yet	3s	512 MB	Judgeable
Food Display ArrangementGiven a row of food type IDs, find the fewest types to move to the ends so that every remaining type forms one contiguous block.	Medium5	GreedySorting+1	No attempts yet	1s	1024 MB	Judgeable
xGiven a vertical cylinder and aircraft flying straight lines with descent, find the times each aircraft enters and exits the cylinder, if it does.	Medium5	GeometryMath	No attempts yet	1s	1024 MB	Judgeable
Hidden MessageCount the ways to split the original phrase into three subsequences that spell the given sub-phrases, modulo 1,000,000,007.	Medium5	Dynamic programmingString	No attempts yet	1s	1024 MB	Judgeable
Make the teamAssign each video a distinct whole-hour start time so that the latest finish time is as early as possible.	Medium5	GraphBinary search	No attempts yet	1s	1024 MB	Judgeable
Wedding DJGiven song fun levels, find the fewest 'change all songs of level x to level y' operations that make the playlist's fun levels never decrease.	Medium5	IntervalsSorting+2	No attempts yet	1s	1024 MB	Judgeable
Gone FishingGiven a net of radius R and n fish positions, find the most fish that fit inside a single circle of radius R.	Medium5	GeometryBrute force	No attempts yet	1s	1024 MB	Judgeable
Team Shirts/JerseysGiven friends' jersey numbers and a target t, decide whether Travis can add one number from 1 to 99 so that concatenating some of the numbers gives exactly t.	Medium5	BacktrackingDynamic programming+1	No attempts yet	1s	1024 MB	Judgeable
Rotating CardsGiven a stack of n shuffled cards, find the minimum total label cost of rotating cards so that cards 1 through n can be discarded in order.	Medium5	GreedyPrefix sum+1	No attempts yet	1s	1024 MB	Judgeable
Jedi and the Galactic EmpireFind the fewest blaster shots that get past one or two Jedi, given the shot times and each Jedi's reaction time between blocks.	Medium5	Dynamic programmingSorting+1	No attempts yet	1s	1024 MB	Judgeable
Rising TidesFind the path from the top-left to the bottom-right cell of a grid that maximizes the smallest remaining ceiling height as the water rises 1 per second.	Medium5	GraphBFS+2	No attempts yet	2s	1024 MB	Judgeable
Choosing the GatewayGiven a tree whose links carry XOR values, find the gateway node that minimizes the total count of 1 bits in the header received by all nodes.	Medium5	Bit manipulationTree+1	No attempts yet	1s	1024 MB	Judgeable
Lost EdgeGiven a grid of walls and monsters, the task is to decide whether the player can reach the target level by hunting weaker monsters and then reach the raid cell.	Medium5	BFSHeap+1	No attempts yet	1s	1024 MB	Judgeable
LightbulbsGiven an N by M grid where each bulb works with probability P, find the expected length of the longest horizontal run of working bulbs.	Medium5	Dynamic programmingProbability	No attempts yet	1s	256 MB	Judgeable
Longest PathGiven a directed graph where every pair of vertices has exactly one edge, find a path that visits every vertex exactly once.	Medium5	GraphSorting	No attempts yet	2s	1024 MB	Judgeable
Gift DiscountGiven n gift prices, a budget b, and up to a half-price discounts, find the most gifts you can buy within the budget.	Medium5	GreedySorting+1	No attempts yet	1s	1024 MB	Judgeable
Islands TourIn a directed graph where each island has at most one outgoing zip-line, find the most distinct islands a tour starting anywhere can visit.	Medium5	GraphDFS+1	No attempts yet	1s	1024 MB	Judgeable
Temporal GraphFind the length of the shortest path from s to e in a temporal graph, where the chosen edges must have strictly increasing time labels.	Medium5	Dynamic programmingGraph+1	No attempts yet	1s	1024 MB	Judgeable
Sunwoo's SetlistCount the ordered song sequences, with repeats allowed, whose running times sum to exactly N minutes, modulo 1,000,000,007.	Medium5	Dynamic programmingMath	No attempts yet	1s	512 MB	Judgeable
Staircase Building (Small)Given column heights, find the fewest blocks to move so that adjacent columns differ by at most 1 in height while the total block count stays the same.	Medium5	Dynamic programmingArray	No attempts yet	2s	512 MB	Judgeable
Hyundai Mobis Autonomous Driving SystemFind the shortest path from the top-left to the bottom-right of a grid that visits at least one waypoint, using up to K uses of a 5x5 jump pattern.	Medium5	BFSShortest path+1	No attempts yet	1s	512 MB	Judgeable
Domino TopplingGiven N dominoes with positions a_i and lengths l_i, count the minimum number that must be pushed by hand so every domino falls in a chain.	Medium5	StackSorting+1	No attempts yet	1s	1024 MB	Judgeable
Harvesting apples and pears from k tree nodesPick a connected set of at most k nodes containing root 0 to maximize apples times pears, then print the apple and pear counts.	Medium5	Dynamic programmingTree	No attempts yet	3s	512 MB	Judgeable
Knitting PatternsFor each wool colour, find the minimum total cost of knitting a pattern, counting stitches used, stitches stranded, and each start or end of a colour.	Medium5	Dynamic programmingString	No attempts yet	3s	2048 MB	Judgeable
Kiosk InstallationFind a plot for the kiosk that every other plot can reach under the greedy walk rule, and report the longest walk, or print impossible.	Medium5	GraphBFS+1	No attempts yet	8s	1024 MB	Judgeable
Coffee Cup ComboGiven a binary string marking which lecture halls have coffee machines, find the most lectures Jonna can stay awake in while carrying at most two cups.	Medium5	Dynamic programmingGreedy	No attempts yet	1s	1024 MB	Judgeable
PatioCount contiguous substrings of a tile string that form a square patio with a one-tile border of one color and an interior of the other.	Medium5	StringPrefix sum+1	No attempts yet	3s	1024 MB	Judgeable
Gomgomi and the CafeteriaGiven headcounts and meal tickets for three foods plus a cyclic 3-to-1 exchange event, find the maximum number of people that can be fed.	Medium5	GreedyMath+1	No attempts yet	2s	1024 MB	Judgeable
Circus KnightGiven dolphin IDs, find the largest group of dolphins that can reach each other when two dolphins are linked if their IDs share a divisor greater than 1.	Medium5	MathUnion-find+1	No attempts yet	1s	1024 MB	Judgeable
Gomgom and the TournamentGiven 2^K skill scores and the prize for each round, find the expected prize Gomgom (participant 1) wins in a random bracket, modulo 998244353.	Medium5	CombinatoricsProbability+1	No attempts yet	2s	1024 MB	Judgeable
Mathematical Lowest Common AncestorGiven vertices a and b in a tree where each x has parent x divided by its smallest prime factor, find the number of their lowest common ancestor.	Medium5	Number theoryMath+1	No attempts yet	1s	1024 MB	Judgeable
Forbidden TurnsFind the shortest distance from v to w in a directed graph where the path never takes a forbidden turn (x, y, z) as two consecutive edges.	Medium5	Shortest pathGraph+1	No attempts yet	2s	1024 MB	Judgeable
Data CentersEach service removes m_i machines from the c_i data centers with the most free machines, and the task asks for the final counts in descending order.	Medium5	SortingSimulation	No attempts yet	2s	1024 MB	Judgeable
Alien Invader YooniGiven building heights, each day every tallest building drops by 1; find the total number of lasers fired over D days.	Medium5	SortingGreedy+1	No attempts yet	1s	1024 MB	Judgeable
Two RoadsGiven a directed graph, for each of Q scenarios that add two one-way roads, find the shortest time from home S to office T, or -1 if unreachable.	Medium5	Shortest pathGraph	No attempts yet	3s	1024 MB	Judgeable
SplitstreamGiven a network of split and merge nodes fed by 1 to m, answer queries for the kth number on any output node.	Medium5	RecursionSimulation+1	No attempts yet	3s	1024 MB	Judgeable
Eating Apples QuicklyOn a 5 x 5 grid, find the fewest moves for a student to eat 3 apples, where each cell becomes an obstacle after the student leaves it. Print -1 if impossible.	Medium5	BacktrackingBrute force	No attempts yet	1s	512 MB	Judgeable
Brothers in ArmsEach city is an edge between its top and bottom symbols. For each query, find the shortest friendship chain length between two cities, or -1 if none exists.	Medium5	Shortest pathGraph	No attempts yet	10s	1024 MB	Judgeable
Interview QuestionGiven a transcript of consecutive Fizz Buzz outputs, find any values of a and b that could have produced it.	Medium5	Number theoryBrute force+1	No attempts yet	1s	1024 MB	Judgeable
Justice ServedEach suspect is a time interval, and the task is to find for each one the longest chain of alibis from suspects whose stays fully contain it.	Medium5	SortingDynamic programming	No attempts yet	5s	1024 MB	Judgeable
DeforestationGiven a tree of segment weights and a carrying limit W, find the minimum number of pieces needed so that each piece weighs at most W.	Medium5	GreedyTree+1	No attempts yet	2s	1024 MB	Judgeable
PermutationsGiven an inversion table of a permutation, output the permutation's cycle notation with each cycle starting from its smallest element.	Medium5	ArrayBinary search+1	No attempts yet	2s	1024 MB	Judgeable
Cutting with LasersGiven a closed path of axis-parallel laser cuts on a sheet, find the area of the largest enclosed piece that does not touch the sheet edge.	Medium5	BFSMatrix+1	No attempts yet	1s	1024 MB	Judgeable
Eliminating BalloonsGiven balloon heights from left to right, find the fewest arrows where each arrow pops balloons at heights H, H-1, H-2, and so on in order.	Medium5	GreedyArray	No attempts yet	1s	1024 MB	Judgeable
Geometry of TrianglesGiven triangles of a triangulated polygon, pick the subset with the least total area so that every side still belongs to a chosen triangle.	Medium5	Dynamic programmingTree+1	No attempts yet	1s	1024 MB	Judgeable
Helping the TransitGiven N reference points and M one-way streets, find the fewest one-way bridges to add so that every point can reach every other point.	Medium5	GraphDFS+1	No attempts yet	1s	1024 MB	Judgeable