Interview core

Mediums from real onsites

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Total results3,617 problems

Anadrome split
Medium6
Dynamic programming, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Aliens
Medium6
Hash map, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cow Checklist
Medium6
Dynamic programming, Geometry
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Array Characteristic
Medium6
Array, Prefix sum
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Oland must not fall
Medium6
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sort the Table
Medium6
Sorting, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Red button, blue button
Medium6
Math, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Plane Game
Medium6
Geometry, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The Jewel Thief
Medium6
Number theory, Greedy
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Attendance Record
Medium6
Greedy, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Attendance Record 2
Medium6
Greedy, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
XOR Equation
Medium6
Math, Bit manipulation
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Armistice Negotiation
Medium6
Geometry, Divide and conquer+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Grid Game
Medium6
Simulation, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Adding edges one by one
Medium6
Union-find, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cutting edges 2
Medium6
Minimum spanning tree, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sherlock and Parentheses (Large)
Medium6
String, Greedy+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Jane's Flower Shop (Small)
Medium6
Binary search, Math+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Rather Perplexing Showdown (Small)
Medium6
Divide and conquer, Recursion+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Two Operations
Medium6
BFS, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Foehn Phenomena
Medium6
Array, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Sequence and Queries 16
Medium6
Segment tree, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Prime Village
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Sequence and Queries 17
Medium6
Segment tree, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Break Walls and Move 2
Medium6
BFS, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hoof, Paper, Scissors (Gold)
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Why Did the Cow Cross the Road 7
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Why Did the Cow Cross the Road 9
Medium6
Array, Hash map+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Why Did the Cow Cross the Road 4
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Assembly Required
Medium6
Heap, Greedy
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Junan's Rampage
Medium6
BFS, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Bovine Genomics (Gold)
Medium6
String, Hash map+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Paired Up
Medium6
Greedy, Two pointers+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Memory
Medium6
Game theory, Math+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Taekwondo King
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Marbles on the tree
Medium6
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hourglass
Medium6
Graph, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
After-Party Drink Cap
Medium6
Greedy, Binary search+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tiling the Shower Floor (Large)
Medium6
Divide and conquer, Recursion+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Island Trip
Medium6
Graph, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Transforming Robot
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Mission Improbable
Medium6
Greedy, Array+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Posterize
Medium6
Dynamic programming, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Scenery
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
A rain of shooting stars
Medium6
Array, Sorting+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Crush Fever
Medium6
DFS, Brute force+2
No attempts yet
Time limit
1.5s
Memory limit
512 MB
Judgeable
Sickly Yunho
Medium6
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Tile Flipping (Easy)
Medium6
Implementation, Simulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Brave Warrior Jinsu
Medium6
Sorting, Binary search+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Ant Nest
Medium6
Trie, Tree+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Bumper to bumper traffic
Medium6
Implementation, Simulation+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Bot or not
Medium6
Implementation, Hash map+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The Climbing Wall
Medium6
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cows on a Leash
Medium6
Greedy, Intervals+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Fashion Show
Medium6
Graph, Two pointers+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Alphabet Cake (Small)
Medium6
Greedy, Implementation+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Ratatouille (Large)
Medium6
Greedy, Two pointers+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Fresh Chocolate (Small)
Medium6
Greedy, Math+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Dumpling shop owner Seungwon Park
Medium6
Dynamic programming, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Two Water Jugs
Medium6
BFS, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cats
Medium6
Greedy, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
16 MB
Judgeable
Subarray XOR sums
Medium6
Prefix sum, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Mensa Safe
Medium6
Graph, Simulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Elevator Prank
Medium6
Bit manipulation, Brute force+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Turning Off the Lights
Medium6
Brute force, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Game Map
Medium6
Graph, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Philosopher's Walk
Medium6
Divide and conquer, Recursion+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Go around the Labyrinth
Medium6
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Import Spaghetti
Medium6
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cued In
Medium6
Greedy, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Hipercampo
Medium6
Geometry, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
A Question of Ingestion
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Honey Heist
Medium6
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Orderly Class
Medium6
String, Two pointers+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Faulty Robot
Medium6
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Straight Shot
Medium6
Math, Binary search+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Jumping Haybales
Medium6
BFS, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Intuidiff II
Medium6
Dynamic programming, Intervals+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Happy Sequence
Medium6
Math, Implementation+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Zoning
Medium6
BFS, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hay Bales
Medium6
Greedy, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hidden Hierarchy
Medium6
Tree, Hash map+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Friend Palindrome
Medium6
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Designing the Toy
Medium6
Math, Greedy+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Pavers
Medium6
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Club Room Repairs
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
A Strange Tournament
Medium6
Dynamic programming, Divide and conquer+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Card block reversal
Medium6
Array, Hash map+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Barareh on Fire
Medium6
BFS, Graph
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Roof
Medium6
Array, Prefix sum+2
No attempts yet
Time limit
1.5s
Memory limit
128 MB
Judgeable
False cards
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tataramon
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
A Packing Problem
Medium6
Geometry, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Harry Potter and the Vector Spell
Medium6
Graph, Union-find+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Enumerating Brackets
Medium6
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Barn Painting
Medium6
Tree, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Haybale Feast
Medium6
Two pointers, Sliding window+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The Bovine Shuffle
Medium6
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Minimum edit
Medium6
Dynamic programming, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Kindergarten candy bags
Medium6
Binary search, Greedy+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Anadrome splitSplit a lowercase word into the fewest substrings that are each anagrams of some palindrome, breaking ties by the lexicographically smallest printed line.	Medium6	Dynamic programmingGreedy+1	No attempts yet	1s	128 MB	Judgeable
AliensGiven N points, choose an integer axis value s minimizing new points needed so the set is symmetric about x = s/2, then output those points. Ties go to the smallest s, output sorted by x then y.	Medium6	Hash mapSorting+2	No attempts yet	1s	128 MB	Judgeable
Cow ChecklistFind the cheapest path that visits all Holsteins in order and all Guernseys in order, starting at Holstein 1 and ending at Holstein H.	Medium6	Dynamic programmingGeometry	No attempts yet	2s	512 MB	Judgeable
Array CharacteristicMove one element to any position and maximize the weighted sum of A_i times its new index.	Medium6	ArrayPrefix sum	No attempts yet	2s	512 MB	Judgeable
Oland must not fallGiven hospital supplies, demands, and an undirected tunnel graph with unit edge costs, find the minimum total cost to balance every hospital, or -1 if impossible.	Medium6	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
Sort the TableGiven an N by M grid holding a permutation of 1 to N*M, decide whether swapping whole rows and whole columns can make the row-major reading order sorted ascending.	Medium6	SortingImplementation+2	No attempts yet	2s	512 MB	Judgeable
Red button, blue buttonGiven (a,b), reach (c,d) using +1 on both coordinates or doubling both, with the fewest presses, or report -1.	Medium6	MathGreedy+2	No attempts yet	2s	512 MB	Judgeable
Plane GameGiven N points, rotate and translate them arbitrarily so that as many points as possible lie on the two coordinate axes; output that maximum count.	Medium6	GeometryBrute force+2	No attempts yet	2s	512 MB	Judgeable
The Jewel ThiefFactor k into the largest possible count of integers greater than 1 whose product is k, and list them in ascending order.	Medium6	Number theoryGreedy	No attempts yet	2s	512 MB	Judgeable
Attendance RecordRearrange the letters of a record over A, B, C so the result is valid (B needs one rest day, C needs two) and lexicographically smallest.	Medium6	GreedyBrute force+2	No attempts yet	2s	512 MB	Judgeable
Attendance Record 2Given a string of A, B, C, rearrange its letters into the lexicographically smallest valid schedule where B needs a rest day after working and C needs two.	Medium6	GreedyString+2	No attempts yet	2s	512 MB	Judgeable
XOR EquationCount ordered pairs of positive integers A and B with A+B=S and A xor B=X.	Medium6	MathBit manipulation	No attempts yet	2s	512 MB	Judgeable
Armistice NegotiationGiven two sets of points, decide whether a straight line exists that keeps each country's cities strictly on opposite sides.	Medium6	GeometryDivide and conquer+2	No attempts yet	2s	512 MB	Judgeable
Grid GameEach cell becomes alive if it or an edge neighbor was alive, so the live region grows by repeated dilation; count live cells after K steps.	Medium6	SimulationBFS+2	No attempts yet	2s	512 MB	Judgeable
Adding edges one by oneAdd the given weighted edges one at a time in any order and stop once s and t become connected; maximize the total weight of added edges at that moment.	Medium6	Union-findGreedy+2	No attempts yet	2s	512 MB	Judgeable
Cutting edges 2Given a weighted undirected graph and two vertices s and t, find the minimum total weight of edges to delete so that s and t end up disconnected, choosing the deletion order.	Medium6	Minimum spanning treeGraph+2	No attempts yet	2s	512 MB	Judgeable
Sherlock and Parentheses (Large)Given L opening and R closing parentheses, arrange a string of length L+R that maximizes the number of non-empty balanced substrings; output that maximum.	Medium6	StringGreedy+2	No attempts yet	5s	512 MB	Judgeable
Jane's Flower Shop (Small)Find the internal rate of return r that makes the net present value of a monthly cash flow sequence equal zero, then print it to 12 decimals.	Medium6	Binary searchMath+2	No attempts yet	5s	512 MB	Judgeable
Rather Perplexing Showdown (Small)Find the alphabetically smallest left-to-right lineup of R rocks, P papers, and S scissors so that a single-elimination bracket never pairs identical moves.	Medium6	Divide and conquerRecursion+2	No attempts yet	5s	512 MB	Judgeable
Two OperationsStarting from X = Y = 1, repeatedly add one variable to the other, and find the shortest (then lexicographically smallest) operation string that makes N appear.	Medium6	BFSGraph+2	No attempts yet	2s	512 MB	Judgeable
Foehn PhenomenaAfter each range add to altitudes, report the wind temperature at spot N, where the total depends on the altitude differences between adjacent spots.	Medium6	ArrayPrefix sum+1	No attempts yet	1s	256 MB	Judgeable
Sequence and Queries 16Maintain an array under point updates and range queries that ask for the leftmost index of the minimum value in a subarray.	Medium6	Segment treeArray+2	No attempts yet	2s	512 MB	Judgeable
Prime VillageGiven 2D points, find the shortest path from a start to a target where every edge must have a prime truncated Euclidean distance.	Medium6	GraphShortest path+2	No attempts yet	2s	256 MB	Judgeable
Sequence and Queries 17Maintain an array under point updates and answer range-minimum queries over subarrays.	Medium6	Segment treeArray+2	No attempts yet	2s	512 MB	Judgeable
Break Walls and Move 2Find the shortest path length from the top-left to the bottom-right of an N by M grid, where you may break at most K walls along the way.	Medium6	BFSGraph+2	No attempts yet	2s	512 MB	Judgeable
Hoof, Paper, Scissors (Gold)Given John's sequence of N gestures and at most K gesture switches, find the maximum number of games Bessie can win.	Medium6	Dynamic programmingGreedy+2	No attempts yet	2s	512 MB	Judgeable
Why Did the Cow Cross the Road 7On an N x N grid, find the fastest route from the top-left to the bottom-right cell when every third move forces Bessie to spend that cell's eating time.	Medium6	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
Why Did the Cow Cross the Road 9Given a circular sequence where each cow label appears exactly twice, count pairs of cows whose chords necessarily cross.	Medium6	ArrayHash map+2	No attempts yet	2s	512 MB	Judgeable
Why Did the Cow Cross the Road 4Match chickens, each available at a single time, to cows whose interval covers that time, so that as many cows as possible get help.	Medium6	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
Assembly RequiredGiven several lists of piece values, output the k smallest sums of picking one value from each list.	Medium6	HeapGreedy	No attempts yet	2s	512 MB	Judgeable
Junan's RampageEach jump clears all friends in the four straight rays from Junan's cell until the first friend in each direction; find the fewest jumps to clear the culprit's cell.	Medium6	BFSGraph+2	No attempts yet	2s	512 MB	Judgeable
Bovine Genomics (Gold)Given N spotted and N plain DNA strings of length M, find the shortest window of consecutive positions whose substrings separate every spotted string from every plain one.	Medium6	StringHash map+2	No attempts yet	2s	512 MB	Judgeable
Paired UpPair up M cows with given milk outputs to minimize the maximum sum in any pair, where each pair's time is A+B. Input gives counts and output values in compressed form.	Medium6	GreedyTwo pointers+2	No attempts yet	2s	512 MB	Judgeable
MemoryGiven R times C face-down cards forming pairs, find the best-case and worst-case number of actions a perfect-memory player needs to clear the board.	Medium6	Game theoryMath+2	No attempts yet	1s	256 MB	Judgeable
Taekwondo KingWith S < T, using combo A doubles S but adds 3 to T, and combo B adds 1 to S. Find the fewest kicks that make S equal T.	Medium6	Dynamic programmingGreedy+2	No attempts yet	2s	128 MB	Judgeable
Marbles on the treeGiven a rooted ordered binary tree, find the leaf where the K-th marble stops, where each marble at a two-child node goes to the left if left subtree has at most the right subtree's resting marbles, else right.	Medium6	TreeDFS+2	No attempts yet	1s	128 MB	Judgeable
HourglassCount subgraphs formed by two triangles that share exactly one vertex, in an undirected graph with up to 200 vertices.	Medium6	GraphCombinatorics+2	No attempts yet	1s	128 MB	Judgeable
After-Party Drink CapFind the smallest cap S such that each person i gets an integer amount in [L_i, min(R_i, S)] and the amounts sum exactly to T.	Medium6	GreedyBinary search+2	No attempts yet	1s	128 MB	Judgeable
Tiling the Shower Floor (Large)Fill a 2^K by 2^K grid with L shaped trominoes leaving one drain cell empty, using the specified recursive placement and numbering scheme.	Medium6	Divide and conquerRecursion+2	No attempts yet	1s	512 MB	Judgeable
Island TripGiven an undirected graph with node heights, for each query (A, K) find the minimum height reachable from A in exactly K edge steps, or -1 if impossible.	Medium6	GraphDynamic programming+2	No attempts yet	1s	256 MB	Judgeable
Transforming RobotGiven N digit strings of equal length, move between states with cost equal to the sum of squared digit differences per position, and find the minimum cost from a start state to a target state.	Medium6	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
Mission ImprobableGiven a grid of pile heights, find the maximum number of crates that can be removed while keeping every row maximum, column maximum, and empty/non-empty pattern unchanged.	Medium6	GreedyArray+2	No attempts yet	1s	512 MB	Judgeable
PosterizeChoose k allowed red values so the weighted sum of squared distances from the d distinct intensities is minimized.	Medium6	Dynamic programmingMath+2	No attempts yet	2s	512 MB	Judgeable
SceneryGiven n time windows and a fixed photo duration t, decide whether all photos can be scheduled as non-overlapping intervals.	Medium6	GreedySorting+2	No attempts yet	6s	512 MB	Judgeable
A rain of shooting starsPlace an axis-aligned square of side L to cover as many of K points as possible, counting points on any edge as covered.	Medium6	ArraySorting+2	No attempts yet	2s	256 MB	Judgeable
Crush FeverOn an N by M grid of 5 piece kinds, choose 3 taps; each tap clears the connected same-kind group of the tapped cell and scores size squared, with pieces falling down after each tap. Maximize total points.	Medium6	DFSBrute force+2	No attempts yet	1.5s	512 MB	Judgeable
Sickly YunhoGiven a string of B, L, D doses, remove from either end in the fixed order B, L, D, B, L, D... and find the most doses removable before the required dose is missing from both ends.	Medium6	Dynamic programmingArray+2	No attempts yet	1s	512 MB	Judgeable
Tile Flipping (Easy)Given the first row of an N by N black/white board, fill the remaining rows so that flipping every black tile once (which also flips its orthogonal neighbors) turns the whole board white.	Medium6	ImplementationSimulation+2	No attempts yet	1s	512 MB	Judgeable
Brave Warrior JinsuGiven N enemy stat triples and a target K, find the minimum total stat points so Jinsu's strength, agility, and intelligence let him dominate at least K enemies.	Medium6	SortingBinary search+2	No attempts yet	1s	256 MB	Judgeable
Ant NestGiven paths of food names from the top floor down, print the merged tree with each node indented by two dashes per depth and children in dictionary order.	Medium6	TrieTree+2	No attempts yet	1s	256 MB	Judgeable
Bumper to bumper trafficTwo cars 4.4 m long start stopped on a line and alternate between stopping and driving at 1 m/s at given times; decide whether they ever touch, giving the first contact second rounded up.	Medium6	ImplementationSimulation+2	No attempts yet	4s	512 MB	Judgeable
Bot or notScore pairs of secondary accounts by shared posts they follow, then count accounts similar to a known human.	Medium6	ImplementationHash map+1	No attempts yet	2s	512 MB	Judgeable
The Climbing WallGiven holds on a wall, find the fewest holds Bessie must step on to climb from within 1000 mm of the ground to within 1000 mm of the top, moving only between holds at most 1000 mm apart.	Medium6	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
Cows on a LeashGiven N intervals, find the fewest half-integer cut points so that every interval contains at least one chosen point.	Medium6	GreedyIntervals+1	No attempts yet	2s	512 MB	Judgeable
Fashion ShowGiven a legal partial placement of +, x, and o models on an N by N grid, add or upgrade models to maximize style points under the row/column and diagonal rules.	Medium6	GraphTwo pointers+2	No attempts yet	5s	512 MB	Judgeable
Alphabet Cake (Small)Assign every blank cell of a small grid to an existing letter so each letter occupies one rectangle, choosing the lexicographically smallest result.	Medium6	GreedyImplementation+2	No attempts yet	5s	512 MB	Judgeable
Ratatouille (Large)Given amounts of each ingredient, pair packages into kits so that each package in a kit is within 90 to 110 percent of the recipe amount for the kit's integer serving count, maximizing kits.	Medium6	GreedyTwo pointers+1	No attempts yet	5s	512 MB	Judgeable
Fresh Chocolate (Small)Choose the order of groups so that as many as possible receive only chocolate from freshly opened packs, given that leftovers must be finished first.	Medium6	GreedyMath+2	No attempts yet	5s	512 MB	Judgeable
Dumpling shop owner Seungwon ParkMake at most limited numbers of m filler dumplings and unlimited filler-free ones from n grams of flour to maximize sales.	Medium6	Dynamic programmingGreedy+1	No attempts yet	2s	512 MB	Judgeable
Two Water JugsGiven two jug capacities and a target pair of water amounts, find the minimum fills, empties, and pours from (0,0) or report -1.	Medium6	BFSGraph+2	No attempts yet	2s	512 MB	Judgeable
CatsFind the minimum number of moves to reorder a line of cats, dogs, and lions so no cat is adjacent to a dog.	Medium6	GreedyDynamic programming+2	No attempts yet	1s	16 MB	Judgeable
Subarray XOR sumsFor a sequence, count how often each XOR value appears among all contiguous subarrays, then report the most frequent value, breaking ties by choosing the smallest.	Medium6	Prefix sumBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
Mensa SafeEach grid cell points to another cell; find the start that visits all N*N cells exactly once before repeating, or report none or many.	Medium6	GraphSimulation+2	No attempts yet	2s	512 MB	Judgeable
Elevator PrankEach move toggles a fixed set of buttons and costs N, N/2, N/2, or N/3 seconds; count the distinct button states reachable with total time at most m, including pressing nothing.	Medium6	Bit manipulationBrute force+2	No attempts yet	1s	512 MB	Judgeable
Turning Off the LightsGiven a 10x10 grid of lit and unlit bulbs, find the minimum presses so that every bulb ends up off.	Medium6	Brute forceBit manipulation+2	No attempts yet	1s	128 MB	Judgeable
Game MapGiven an undirected connected graph, find the longest simple path where the degree of each successive vertex strictly increases.	Medium6	GraphDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Philosopher's WalkGiven the step index m along a Hilbert curve of side n = 2^k, find the cell coordinates (x, y) of that step.	Medium6	Divide and conquerRecursion+2	No attempts yet	0.5s	512 MB	Judgeable
Go around the LabyrinthDecide whether a walk from the top-left corner can visit the other three corners and come back, where each non-entrance room collapses after one visit.	Medium6	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
Import SpaghettiFind a shortest cycle in a directed dependency graph and print it in lexicographically smallest rotation order, or report that none exists.	Medium6	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
Cued InGiven the balls left on a snooker table, compute the maximum points a player can score in one run following the red-colour alternation rules.	Medium6	GreedyImplementation+2	No attempts yet	1s	512 MB	Judgeable
HipercampoGiven two anchors on the x-axis and N points above, choose the largest subset whose segments to both anchors meet only at the anchors.	Medium6	GeometrySorting+2	No attempts yet	1s	1024 MB	Judgeable
A Question of IngestionGiven n hourly courses with calorie counts, maximize total calories eaten when the per-hour limit starts at m, shrinks to two thirds while eating, and resets after two skipped hours.	Medium6	Dynamic programmingGreedy+2	No attempts yet	2s	512 MB	Judgeable
Honey HeistBuild the adjacency of a hexagonal honeycomb of side R, remove wax cells, and find the shortest number of chewed cells from A to B, checking it against N.	Medium6	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
Orderly ClassGiven two equal-length strings A and B, count the intervals in A such that reversing that interval turns A into B.	Medium6	StringTwo pointers+2	No attempts yet	2s	512 MB	Judgeable
Faulty RobotGiven a directed graph where at most one designated forced edge leaves each node, count the nodes where the robot can end up stopping if it breaks the forced rule at most once along the way.	Medium6	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
Straight ShotChoose a fixed heading so a robot crossing north-south moving sidewalks lands at (X,0); report the travel time or "Too hard" if it exceeds 2X/v.	Medium6	MathBinary search+1	No attempts yet	1s	512 MB	Judgeable
Jumping HaybalesOn an n by n grid with haybale obstacles, find the fewest jumps of length 1 to k moving only east or south from the top-left corner to the bottom-right corner, or -1 if unreachable.	Medium6	BFSDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Intuidiff IIGiven intervals in the order they appear in a modified document, choose a subsequence of intervals whose original ranges strictly increase; maximize total characters left plain.	Medium6	Dynamic programmingIntervals+2	No attempts yet	4s	512 MB	Judgeable
Happy SequenceChange a sequence with unit-cost edits so every interior term equals the sum of its two neighbours, minimizing total edits.	Medium6	MathImplementation+2	No attempts yet	3s	512 MB	Judgeable
ZoningGiven an n by n grid labeled 1, 2, 3, find the maximum over all cells labeled 1 of the Manhattan distance to the nearest cell labeled 3.	Medium6	BFSGraph+2	No attempts yet	2s	512 MB	Judgeable
Hay BalesGiven a string of C and P, each move sorts any three consecutive characters so all C come before all P; find the minimum number of moves to fully sort the whole row.	Medium6	GreedyString+2	No attempts yet	2s	512 MB	Judgeable
Hidden HierarchyBuild a directory tree from file paths, and print the smallest set of directories (expanding or collapsing as needed) that covers every directory whose total size is at least t.	Medium6	TreeHash map+2	No attempts yet	1s	512 MB	Judgeable
Friend PalindromeGiven a friendship graph on up to 20 students, find the largest number of students that can form a palindrome-like line where every student except the possible middle one is paired with a friend.	Medium6	Dynamic programmingBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
Designing the ToyGiven three target projection areas a, b, c, find the minimum number of voxels in a 3D figure whose three orthogonal projections have those exact areas, or report -1.	Medium6	MathGreedy+2	No attempts yet	3s	512 MB	Judgeable
PaversCount the tilings of a 2 x n board with 1x1 squares, 2x1 rectangles, and L-trominoes, and sum the total number of each paver over all tilings.	Medium6	Dynamic programmingCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Club Room RepairsAssign each club at most one room and each room at most one club, where Jongbin covers max(0, cost - budget) up to X total; maximize clubs housed.	Medium6	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
A Strange TournamentGiven a sequence of distinct powers, choose a non-crossing knockout bracket minimizing the total absolute difference over all matches played.	Medium6	Dynamic programmingDivide and conquer+2	No attempts yet	2s	512 MB	Judgeable
Card block reversalGiven a permutation of 1..N, choose one contiguous block to reverse so that the final number of positions i with card i is maximized, breaking ties by leftmost start then leftmost end.	Medium6	ArrayHash map+1	No attempts yet	1s	128 MB	Judgeable
Barareh on FireFind the shortest time from s to t on a grid where fire spreads to all eight neighbors every k seconds and blocks the path.	Medium6	BFSGraph	No attempts yet	2s	512 MB	Judgeable
RoofGiven N column heights, pick a peak position and height so the roof shape h_j = peak - \|peakpos - j\| is positive everywhere, minimizing total absolute changes.	Medium6	ArrayPrefix sum+2	No attempts yet	1.5s	128 MB	Judgeable
False cardsArrange N cards so exactly K are false, where each card claims at least a_i cards below it are false; output the specified canonical arrangement or -1.	Medium6	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
TataramonGiven a sequence, pick each value at most twice to maximize the sum, and among all maximum-sum picks output the lexicographically smallest subsequence.	Medium6	GreedySorting+2	No attempts yet	3s	512 MB	Judgeable
A Packing ProblemGiven a rectangle and two circles, decide whether both circles fit inside the rectangle without overlapping, allowing tangency.	Medium6	GeometryMath+2	No attempts yet	2s	512 MB	Judgeable
Harry Potter and the Vector SpellEach of N columns is a binary vector with exactly two 1s; find the rank of this M-by-N matrix over GF(2).	Medium6	GraphUnion-find+2	No attempts yet	1s	256 MB	Judgeable
Enumerating BracketsGiven N and M, print the M-th balanced bracket sequence of length N in lexicographic order, where '(' is smaller than ')'.	Medium6	CombinatoricsDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Barn PaintingCount the proper 3-colorings of a tree consistent with some pre-colored nodes, modulo 1e9+7.	Medium6	TreeDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Haybale FeastPick a contiguous block whose flavor sums to at least M while minimizing the block's maximum spiciness.	Medium6	Two pointersSliding window+2	No attempts yet	2s	512 MB	Judgeable
The Bovine ShuffleGiven a functional graph where each position i sends its cow to a_i, count the positions that hold at least one cow no matter how many shuffles are applied.	Medium6	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
Minimum editCompute the Levenshtein distance between two lowercase strings, using the fewest insert, delete, and replace operations to change A into B.	Medium6	Dynamic programmingString+2	No attempts yet	2s	512 MB	Judgeable
Kindergarten candy bagsAssign N candy bags to N children to minimize the largest absolute difference between each child's candy and the candy of the child they picked; the picking forms a permutation.	Medium6	Binary searchGreedy+2	No attempts yet	2s	256 MB	Judgeable