Interview core

Mediums from real onsites

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Total results3,610 problems

Tide Goes In, Tide Goes Out (Small)
Medium7
Shortest path, Graph+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Stock Charts (Large)
Medium7
Graph, Union-find+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Bribe the Prisoners (Small)
Medium7
Dynamic programming, Divide and conquer+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
What Are Birds? (Large)
Medium7
Array, Intervals+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Cities
Medium7
Minimum spanning tree, Dynamic programming+2
No attempts yet
Time limit
4s
Memory limit
256 MB
Judgeable
Oil
Medium7
Geometry, Sorting+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Problem Preparation
Medium7
Math, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Bribing the Prisoners
Medium7
Dynamic programming, Intervals+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Fox and Card Game
Medium7
Game theory, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
New Hanoi Tower
Medium7
BFS, Implementation+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Two Weights
Medium7
Shortest path, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Karaoke
Medium7
Dynamic programming, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Palindrome Walk
Medium7
BFS, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Scrooge Minho 2
Medium7
Tree, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hongjun and Antimatter
Medium7
Dynamic programming, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Delete Files
Medium7
Dynamic programming, Geometry+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Celtic Symmetry
Medium7
Geometry, Hash map+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Gas Stations
Medium7
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Millionaire Madness
Medium7
Graph, Binary search+2
No attempts yet
Time limit
20s
Memory limit
512 MB
Judgeable
Dungeon
Medium7
BFS, Simulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Stephen Cook
Medium7
Game theory, Dynamic programming+2
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Largest XOR sum subarray
Medium7
Bit manipulation, Trie+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Gondolas
Medium7
Dynamic programming, Sorting+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Trucks
Medium7
Graph, Minimum spanning tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Countries at War
Medium7
Shortest path, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Perfect Choir
Medium7
Math, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Road Construction
Medium7
Graph, Shortest path+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Expect to Wait
Medium7
Prefix sum, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Longest Increasing Subsequence 4
Medium7
Dynamic programming, Binary search+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Probability
Medium7
Dynamic programming, Probability+2
No attempts yet
Time limit
1.5s
Memory limit
512 MB
Judgeable
Formula
Medium7
Graph, Bit manipulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Majstor
Medium7
Greedy, Sorting+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Arranging Heaps
Medium7
Dynamic programming, Divide and conquer+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Christmas Eve
Medium7
Dynamic programming, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Placing the Cards
Medium7
Graph, Topological sort+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Red Tape Committee (Large)
Medium7
Dynamic programming, Probability+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Close Match (Large)
Medium7
Dynamic programming, Greedy+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Placing Tiles
Medium7
Backtracking, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Longest Palindromic Substring
Medium7
String, String matching+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Counting Palindromes (Small)
Medium7
Dynamic programming, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Ili
Medium7
Graph, DFS+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Mahjong Waiting Tiles
Medium7
Backtracking, Recursion+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Subin and the Melting Candy
Medium7
Dynamic programming, Sorting
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Professional Network
Medium7
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The cube lover
Medium7
Math, Number theory+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Venue Rental (Large)
Medium7
Geometry, Sorting+2
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Bathroom Stalls
Medium7
Heap, Greedy+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Bathroom Stalls (Large)
Medium7
Heap, Greedy+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Binary String Toggle
Medium7
Prefix sum, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Moving 2
Medium7
Dynamic programming, Implementation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Conqueror
Medium7
Minimum spanning tree, Greedy+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
How Many to Be Happy?
Medium7
Minimum spanning tree, Graph+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Envious Exponents
Medium7
Bit manipulation, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Biotechnology laboratory
Medium7
Prefix sum, Two pointers+2
No attempts yet
Time limit
7s
Memory limit
1024 MB
Judgeable
Keeping On Track
Medium7
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Deck of Cards
Medium7
Game theory, Graph+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Initials
Medium7
Dynamic programming, String+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Artist
Medium7
Dynamic programming, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Bricks
Medium7
Dynamic programming, Intervals
No attempts yet
Time limit
0.2s
Memory limit
512 MB
Judgeable
Bumped!
Medium7
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Rhombinoes
Medium7
Graph, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Mizuyokan
Medium7
Dynamic programming, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Minimum Edit 2
Medium7
Dynamic programming, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
We Don't Wanna Work!
Medium7
Tree, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Marble Escape 4
Medium7
BFS, Simulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Road Construction
Medium7
Array, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Yonsei Water Park
Medium7
Dynamic programming, Segment tree+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Solving cubic equations 2
Medium7
Math, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Chicken Delivery
Medium7
Brute force, Backtracking+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Marathon Course
Medium7
Shortest path, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Block Game
Medium7
Dynamic programming, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Please Take My Gift 2
Medium7
Graph, Greedy+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Array and Operations
Medium7
Array, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
A Very Nasty Graph Problem
Medium7
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
It’s a Jungle Out There
Medium7
Intervals, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Unary
Medium7
Dynamic programming, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Junha's Number Theory Assignment (Divmaster)
Medium7
Segment tree, Math+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Blowin' in the Wind
Medium7
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Bee Problem
Medium7
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Jumbled String
Medium7
Combinatorics, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Drive
Medium7
Greedy, Stack+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Empire
Medium7
Tree, Simulation+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Mobilization
Medium7
Greedy, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Festival
Medium7
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hawawa College Student-chan Goes to Hawaii~
Medium7
Dynamic programming, Math+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Playing the Smaller Number
Medium7
Sorting, Greedy+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Strange Power Lines
Medium7
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Largest Value
Medium7
Dynamic programming, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Textbooks
Medium7
Bit manipulation, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
New Salaries
Medium7
Prefix sum, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Highway Decommission
Medium7
Shortest path, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Mount Marathon
Medium7
Array, Stack+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Peg Game for Two
Medium7
DFS, Game theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Adding Parentheses 2
Medium7
Dynamic programming, Math+1
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Back to the Bones
Medium7
Dynamic programming, Probability+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Clockwork Orange
Medium7
BFS, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Imputation
Medium7
Dynamic programming, Tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Super Cheap Party Rooms
Medium7
Intervals, Simulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Graph Automata Player
Medium7
Matrix, Math+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Comfortable String
Medium7
Dynamic programming, String+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Tide Goes In, Tide Goes Out (Small)Find the earliest reach time to an exit on a height map where water falls 10 cm/s and each move takes 1 second when the exit square has at least 20 cm of water else 10 seconds.	Medium7	Shortest pathGraph+1	No attempts yet	5s	512 MB	Judgeable
Stock Charts (Large)Each stock is a k-dimensional point; a chart holds points where one stock strictly dominates another at every time, and we need the minimum number of chains covering all points.	Medium7	GraphUnion-find+2	No attempts yet	5s	512 MB	Judgeable
Bribe the Prisoners (Small)Choose the release order of Q prisoners out of P cells to minimize total bribes, where each release bribes every still-occupied prisoner reachable from it until a boundary or empty cell.	Medium7	Dynamic programmingDivide and conquer+2	No attempts yet	5s	512 MB	Judgeable
What Are Birds? (Large)Given labeled points and the fact that birds are exactly the points in a height interval crossed with a weight interval, classify each query as always bird, never bird, or unknown.	Medium7	ArrayIntervals+2	No attempts yet	5s	512 MB	Judgeable
CitiesGiven a weighted undirected graph, pick a minimum-cost set of edges so that all k special cities (k at most 10) end up in one connected component.	Medium7	Minimum spanning treeDynamic programming+2	No attempts yet	4s	256 MB	Judgeable
OilGiven up to 2000 horizontal segments at distinct points, find the maximum total length of segments intersected by a single non-horizontal line from the origin.	Medium7	GeometrySorting+2	No attempts yet	10s	512 MB	Judgeable
Problem PreparationMaintain an array under point increments and decrements, and after each update answer the sum of ceil(t_i / k) for a given k.	Medium7	MathPrefix sum+2	No attempts yet	2s	256 MB	Judgeable
Bribing the PrisonersRelease Q prisoners from a row of P cells in the order that minimizes bribes paid to neighbors reached by the news. Find that minimum total cost.	Medium7	Dynamic programmingIntervals+1	No attempts yet	2s	512 MB	Judgeable
Fox and Card GameTwo players alternately take the top (Ciel) or bottom (Jiro) card of one of n piles; find both optimal final scores.	Medium7	Game theoryGreedy+2	No attempts yet	2s	512 MB	Judgeable
New Hanoi TowerGiven three rods with up to 10 labeled disks, find the minimum number of moves to sort them so each rod holds only its matching disk type.	Medium7	BFSImplementation+2	No attempts yet	5s	512 MB	Judgeable
Two WeightsGiven an undirected graph with two weights per edge, find the path from 0 to 1 minimizing the product of the two total weight sums.	Medium7	Shortest pathGraph+2	No attempts yet	2s	512 MB	Judgeable
KaraokeAssign each note of a sequence to one of two singers so that the total of the absolute pitch jumps within each singer's subsequence is minimized.	Medium7	Dynamic programmingArray+2	No attempts yet	2s	512 MB	Judgeable
Palindrome WalkGiven an undirected labeled graph, find the length of the shortest walk from vertex 0 to vertex 1 whose edge-label string is a palindrome, or -1 if none exists.	Medium7	BFSGraph+2	No attempts yet	2s	512 MB	Judgeable
Scrooge Minho 2Given a tree with N cities, place the fewest police stations so that every city and every road is covered, where a station covers its city, its neighbors, and all incident roads.	Medium7	TreeDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Hongjun and AntimatterCount contiguous subarrays of length at least 2 that can be split into two disjoint nonempty parts with equal sums, modulo 1e9+7.	Medium7	Dynamic programmingPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
Delete FilesGiven a top-aligned list of name boxes with widths, find the minimum number of axis-aligned rectangle selections whose deletions remove all 'y' files and keep all 'n' files.	Medium7	Dynamic programmingGeometry+2	No attempts yet	5s	512 MB	Judgeable
Celtic SymmetryGiven up to 1000 distinct integer points in the plane, count the distinct lines of symmetry of the set.	Medium7	GeometryHash map+2	No attempts yet	2s	512 MB	Judgeable
Gas StationsIn a connected undirected weighted graph, buy fuel at cities with given prices to travel from city 1 to city N at minimum total cost, with no tank limit.	Medium7	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
Millionaire MadnessGiven a grid of stack heights, find the smallest ladder length L such that a path from the top-left cell to the bottom-right cell only steps up at most L at a time.	Medium7	GraphBinary search+2	No attempts yet	20s	512 MB	Judgeable
DungeonA hero moves on a small grid while rectangular traps slide and freeze at the walls; find the earliest time to reach the exit without ever standing on a trapped cell.	Medium7	BFSSimulation+2	No attempts yet	2s	512 MB	Judgeable
Stephen CookTwo players alternately assign truth values to variables of a boolean formula; Cook moves first and wins if the formula ends true. Decide the winner under optimal play.	Medium7	Game theoryDynamic programming+2	No attempts yet	3s	256 MB	Judgeable
Largest XOR sum subarrayGiven a sequence, find the maximum XOR value over all contiguous subarrays of length at least one.	Medium7	Bit manipulationTrie+2	No attempts yet	10s	512 MB	Judgeable
GondolasPlace G gondolas at integer offsets on a loop of period 2T to minimize the total wait of N skiers, where each skier boards the first departure at or after their arrival.	Medium7	Dynamic programmingSorting+2	No attempts yet	5s	512 MB	Judgeable
TrucksGiven an undirected weighted graph, answer S queries asking for the maximum bottleneck (minimum edge on the best path) between two vertices.	Medium7	GraphMinimum spanning tree+2	No attempts yet	2s	512 MB	Judgeable
Countries at WarGiven directed weighted edges between cities, treat mutually reachable cities as zero-cost (same country), then answer shortest path queries.	Medium7	Shortest pathGraph+2	No attempts yet	2s	512 MB	Judgeable
Perfect ChoirGiven sorted starting notes for N singers, each measure moves one singer up and another down by one; find the minimum measures until all notes are equal, or -1 if impossible.	Medium7	MathGreedy+2	No attempts yet	2s	512 MB	Judgeable
Road ConstructionGiven a weighted bidirectional graph, find the minimum total building cost of a spanning subgraph that keeps every pairwise connection and preserves the shortest distance from the capital to every city.	Medium7	GraphShortest path+2	No attempts yet	8s	512 MB	Judgeable
Expect to WaitGiven a time-ordered schedule of unicycle drops and grouped requests, compute the total wait time of all requesters for each of several starting unicycle counts, or report infinity if anyone is left waiting.	Medium7	Prefix sumBinary search+2	No attempts yet	2s	512 MB	Judgeable
Longest Increasing Subsequence 4Find a longest strictly increasing subsequence of A, and among all of maximum length output the lexicographically smallest one along with its length.	Medium7	Dynamic programmingBinary search+2	No attempts yet	1s	256 MB	Judgeable
ProbabilityGiven probabilities of letters A to D, find the probability that an optimally played game fills a row of n cells in alphabetical order.	Medium7	Dynamic programmingProbability+2	No attempts yet	1.5s	512 MB	Judgeable
FormulaFind the maximum number of edges in a closed trail that uses every important edge at least once, or report that none exists.	Medium7	GraphBit manipulation+1	No attempts yet	1s	128 MB	Judgeable
MajstorChoose a prerequisite-closed set of jobs that maximizes total fee divided by total hours, with the quotient floored.	Medium7	GreedySorting+2	No attempts yet	3s	128 MB	Judgeable
Arranging HeapsDivide N ordered mining points into K groups, each group merging into one heap at its last point, minimizing total weighted distance moved.	Medium7	Dynamic programmingDivide and conquer+2	No attempts yet	2s	512 MB	Judgeable
Christmas EveGiven n weighted warehouses on a line, choose k of them as teleporter sites so that moving every other warehouse's presents into a chosen site gives the least total weighted distance.	Medium7	Dynamic programmingSorting+2	No attempts yet	2s	512 MB	Judgeable
Placing the CardsGiven the top view of overlapping rectangular cards, find the placement order that produces it, choosing the lexicographically smallest valid order.	Medium7	GraphTopological sort+2	No attempts yet	2s	512 MB	Judgeable
Red Tape Committee (Large)Choose exactly K of N members, each with a known Yes probability, to maximize the chance that exactly half vote Yes.	Medium7	Dynamic programmingProbability+2	No attempts yet	5s	512 MB	Judgeable
Close Match (Large)Fill question marks in two equal-length digit strings to make the scores as close as possible, breaking ties by the smallest C then smallest J.	Medium7	Dynamic programmingGreedy+2	No attempts yet	5s	512 MB	Judgeable
Placing TilesGiven a grid with blocked cells, cover every empty cell with 1 x k horizontal or vertical tiles (k is any positive integer, chosen per tile) and minimize the number of tiles.	Medium7	BacktrackingDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Longest Palindromic SubstringGiven a lowercase string of up to 100,000 characters, report the length of its longest palindromic substring.	Medium7	StringString matching+2	No attempts yet	2s	512 MB	Judgeable
Counting Palindromes (Small)Count how many subsequences of a string of length up to 30 are palindromes, treating subsequences that use different positions as distinct.	Medium7	Dynamic programmingString+2	No attempts yet	2s	512 MB	Judgeable
IliGiven a DAG of two-input OR gates where some gate outputs are measured, determine which remaining gate outputs are forced to a single value across all valid assignments of the wires.	Medium7	GraphDFS+2	No attempts yet	4s	1024 MB	Judgeable
Mahjong Waiting TilesGiven a 13 tile mahjong hand numbered 1 to 9, list every tile still available that completes the hand into one head plus four bodies, or into seven distinct heads.	Medium7	BacktrackingRecursion+2	No attempts yet	1s	256 MB	Judgeable
Subin and the Melting CandyStarting at the origin and moving only right or up, visit baskets over time to maximize total candies collected, where a basket's candies shrink by one per time unit.	Medium7	Dynamic programmingSorting	No attempts yet	1s	64 MB	Judgeable
Professional NetworkGiven N people, each joinable when Kevin's current connection count reaches A_i or by paying B_i points, find the minimum total points to connect with everyone.	Medium7	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
The cube loverGiven up to 10^18 unit cubes, find positive integer box dimensions x, y, z with xyz >= K that minimize the surface area 2(xy+yz+zx), breaking ties by lexicographically smallest triple.	Medium7	MathNumber theory+2	No attempts yet	0.5s	512 MB	Judgeable
Venue Rental (Large)Given up to 3000 axis-aligned rectangles, find the total area of their union, counting overlaps once.	Medium7	GeometrySorting+2	No attempts yet	5s	256 MB	Judgeable
Bathroom StallsSimulate K people choosing the emptiest interval by a tie-break rule, and report the gap sizes of the K-th chosen stall.	Medium7	HeapGreedy+2	No attempts yet	5s	512 MB	Judgeable
Bathroom Stalls (Large)Simulate K people choosing bathroom stalls by the maximize-min-then-max-then-leftmost rule, and report the max and min distances for the last chooser when N can be 10^18.	Medium7	HeapGreedy+2	No attempts yet	5s	512 MB	Judgeable
Binary String ToggleApply U range-toggle operations to an all-zero binary string and print the lexicographically largest string among all U+1 intermediate states.	Medium7	Prefix sumGreedy+1	No attempts yet	2s	512 MB	Judgeable
Moving 2Given an N by N grid of candy amounts, collect the most candy over K monotone paths from (1,1) to (N,N), counting each cell only once.	Medium7	Dynamic programmingImplementation+1	No attempts yet	2s	512 MB	Judgeable
ConquerorConquer all cities from city 1, where the k-th city you take costs the edge cost plus (k-1)*t, and minimize the total.	Medium7	Minimum spanning treeGreedy+2	No attempts yet	2s	256 MB	Judgeable
How Many to Be Happy?For each edge find the fewest edges to delete so that it lies in some minimum spanning tree, then sum those counts.	Medium7	Minimum spanning treeGraph+2	No attempts yet	0.5s	512 MB	Judgeable
Envious ExponentsGiven N and k, find the smallest integer greater than N whose binary representation has exactly k ones.	Medium7	Bit manipulationGreedy+2	No attempts yet	2s	512 MB	Judgeable
Biotechnology laboratoryGiven a string of lowercase letters weighted 1 to 26, count how many distinct total weights occur among all non-empty substrings.	Medium7	Prefix sumTwo pointers+2	No attempts yet	7s	1024 MB	Judgeable
Keeping On TrackGiven a tree with n+1 nodes, find the node whose removal splits it worst, then pick the best non-edge to add so the remaining disconnected pairs are minimized.	Medium7	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
Deck of CardsTwo players alternate playing a card matching the table card in color or value; the first unable to move loses, so find the winner under optimal play.	Medium7	Game theoryGraph+2	No attempts yet	5s	512 MB	Judgeable
InitialsEach student's directory starts as last-initial plus first-initial; append letters from the full names so names strictly increase in class order, minimizing total letters added.	Medium7	Dynamic programmingString+2	No attempts yet	3s	512 MB	Judgeable
ArtistChoose exactly K blocks from N to minimize (sum of chosen widths) times (sum of chosen heights), where each block keeps its orientation.	Medium7	Dynamic programmingSorting+2	No attempts yet	1s	512 MB	Judgeable
BricksCount the distinct sets of occupied boxes reachable after M bricks fall, where a brick at an occupied position expands its run left or right.	Medium7	Dynamic programmingIntervals	No attempts yet	0.2s	512 MB	Judgeable
Bumped!Given an undirected weighted road graph and up to 1000 directed free flights, find the cheapest s-to-t trip using at most one flight.	Medium7	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
RhombinoesGiven live equilateral triangles on a W by H board, find the maximum number of non-overlapping rhombinoes, each covering two live triangles that share a side.	Medium7	GraphDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
MizuyokanGiven a bar divided by N-1 score lines into segments of given lengths, cut along some lines so the longest and shortest resulting pieces differ as little as possible.	Medium7	Dynamic programmingBinary search+2	No attempts yet	2s	512 MB	Judgeable
Minimum Edit 2Compute the minimum number of insertions, deletions, replacements, and adjacent swaps needed to turn string A into string B, with both strings up to length 1000.	Medium7	Dynamic programmingString+2	No attempts yet	2s	512 MB	Judgeable
We Don't Wanna Work!Maintain a dynamic set of members whose top floor(20%) by motivation and join time are workhorses, and log every time a member's status flips after each join or departure.	Medium7	TreeSorting+2	No attempts yet	2s	512 MB	Judgeable
Marble Escape 4On a small board with one red marble, one blue marble, and a single hole, tilt until the red marble falls through the hole while the blue never does; report the fewest tilts or -1.	Medium7	BFSSimulation+2	No attempts yet	2s	512 MB	Judgeable
Road ConstructionGiven a permutation, for each query [l,r] reverse that segment and report the number of maximal increasing runs in the resulting array.	Medium7	ArrayMath+2	No attempts yet	1s	128 MB	Judgeable
Yonsei Water ParkGiven N stones in a line with values K_i, pick a starting stone and a sequence of distinct stones where each jump moves at most D positions, maximizing the sum of visited values.	Medium7	Dynamic programmingSegment tree+1	No attempts yet	1s	128 MB	Judgeable
Solving cubic equations 2Find all real roots of a cubic with rational coefficients, printing them rounded to four decimals, using that at least one root is an integer.	Medium7	MathBinary search+2	No attempts yet	2s	512 MB	Judgeable
Chicken DeliveryChoose at most M of the chicken restaurants to keep open so that the sum over all houses of the distance to the nearest open restaurant is minimized.	Medium7	Brute forceBacktracking+2	No attempts yet	1s	512 MB	Judgeable
Marathon CourseChoose a simple path from 1 to N minimizing the cost of its roads, where each road costs C*(P-T)^2 when P > T, and find the largest P whose cost fits budget K.	Medium7	Shortest pathGraph+2	No attempts yet	2s	512 MB	Judgeable
Block GameRemove every block so the heights leave in non-decreasing order, minimizing moves of a machine that walks left and right along the shrinking row.	Medium7	Dynamic programmingGreedy+2	No attempts yet	2s	512 MB	Judgeable
Please Take My Gift 2Given a 1 by N arrow map where every walk stays inside, place the fewest gifts so that a walk from any starting cell hits a gift.	Medium7	GraphGreedy+2	No attempts yet	2s	256 MB	Judgeable
Array and OperationsApply a sequence of global 'add index to each position' updates and range reversals to a zero array, then report the values at m queried positions.	Medium7	ArrayImplementation+2	No attempts yet	2s	512 MB	Judgeable
A Very Nasty Graph ProblemBuild the lexicographically smallest de Bruijn sequence of order N over two symbols, a shortest binary string containing every N-bit number.	Medium7	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
It’s a Jungle Out ThereGiven moving point cars and snake lengths, count how many snakes can find a safe crossing window between two given times without a car touching their body.	Medium7	IntervalsSorting+2	No attempts yet	2s	512 MB	Judgeable
UnaryCount length-N strings of negation and bitwise-NOT that map 0 to M in two's complement, modulo 998244353.	Medium7	Dynamic programmingMath+1	No attempts yet	1s	512 MB	Judgeable
Junha's Number Theory Assignment (Divmaster)Process Q operations on N natural numbers: replace a range with each value's divisor count, or print a range sum. Skip settled ranges using the fast convergence of divisor counts.	Medium7	Segment treeMath+2	No attempts yet	1s	256 MB	Judgeable
Blowin' in the WindOn a connected undirected graph with nodes offering some of g ordered goals, find the fewest edge traversals from node 1 to attain goals 1 to g in order.	Medium7	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
Bee ProblemOn a hexagonal hive grid with solid and empty cells, pick pour sites so honey spreads through connected empty cells; store h units using the fewest pours.	Medium7	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
Jumbled StringGiven counts of subsequences 00, 01, 10, and 11, output a bit string producing exactly those counts.	Medium7	CombinatoricsGreedy+2	No attempts yet	1s	512 MB	Judgeable
DriveGiven D, tank capacity C, consumption E, and stations with distances and prices, find the cheapest way to reach distance D starting with a full tank, or report -1.	Medium7	GreedyStack+2	No attempts yet	1s	256 MB	Judgeable
EmpireSimulate a tree of kingdoms and wars: process each battle in order, transfer vassal subtrees on losses and successful rebellions, then report the root kingdoms sorted by ASCII order.	Medium7	TreeSimulation+2	No attempts yet	1s	256 MB	Judgeable
MobilizationBuy fractional troops within a budget to maximize total health times total potency.	Medium7	GreedyMath+2	No attempts yet	2s	512 MB	Judgeable
FestivalPick exactly one non-overlapping show from each of up to 10 stages so the total known-song count is maximized, or report -1 if no valid selection exists.	Medium7	Dynamic programmingBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
Hawawa College Student-chan Goes to Hawaii~Count the ways to start at island 1 and visit all n islands exactly once using steps +1, +2, or -1 to new islands, modulo 1,000,000,009.	Medium7	Dynamic programmingMath+1	No attempts yet	1s	256 MB	Judgeable
Playing the Smaller NumberGiven two odd-length card sets, decide if one player can force a majority of rounds by winning when their card is strictly smaller, using a matching strategy.	Medium7	SortingGreedy+1	No attempts yet	1s	512 MB	Judgeable
Strange Power LinesKeep a maximum subset of K lines with at most one per pole and no crossings, where pole labels are given in shuffled order. Output the number of lines to remove.	Medium7	Dynamic programmingArray+2	No attempts yet	1s	512 MB	Judgeable
Largest ValueChoose M disjoint contiguous groups in an array of up to 20 numbers so the total sum of their elements is as large as possible.	Medium7	Dynamic programmingPrefix sum+1	No attempts yet	2s	512 MB	Judgeable
TextbooksGiven up to 16 priced book titles and a target word of length at most 10, find the cheapest subset of books whose letters can be rearranged to form the target.	Medium7	Bit manipulationDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
New SalariesSalaries are drawn from nested closed intervals. Compute the expected total pairwise salary gaps and output it divided by N squared.	Medium7	Prefix sumMath+2	No attempts yet	2s	512 MB	Judgeable
Highway DecommissionKeep a minimum-cost subset of highays whose shortest distances to city 1 match the original graph's all-pairs distances to the capital.	Medium7	Shortest pathGraph+2	No attempts yet	2s	512 MB	Judgeable
Mount MarathonGiven up to 52 piles of one card each, repeatedly move a single-card pile onto the pile just to its right if its value is at least the right pile's top card. Find the minimum final number of piles.	Medium7	ArrayStack+2	No attempts yet	2s	512 MB	Judgeable
Peg Game for TwoGiven a weighted triangular peg board with one empty hole, compute the optimal difference of Jacquez's score minus Alia's when both alternately jump and play to maximize their margin.	Medium7	DFSGame theory+2	No attempts yet	2s	512 MB	Judgeable
Adding Parentheses 2Place non-nested parentheses around single operators in a digit-operator expression to make its value as large as possible.	Medium7	Dynamic programmingMath+1	No attempts yet	0.5s	512 MB	Judgeable
Back to the BonesGiven N rolled dice and a target K, reroll any subset once to maximize the chance the sum reaches K, and report 6^N times that probability together with one optimal subset.	Medium7	Dynamic programmingProbability+2	No attempts yet	1s	256 MB	Judgeable
Clockwork OrangeGiven a binary string of occupied corrals, each move picks K and sends half the rabbits K positions right if possible; find the fewest moves to make every corral occupied, or report impossibility.	Medium7	BFSBit manipulation+2	No attempts yet	1s	512 MB	Judgeable
ImputationAssign A, T, C, or G in place of each '?' on tree leaves to minimize total transition costs along edges, summed over all string positions independently.	Medium7	Dynamic programmingTree+2	No attempts yet	2s	512 MB	Judgeable
Super Cheap Party RoomsManage a row of N rooms across new/in/out queries, placing each new room in the leftmost gap of size Y and cleaning it when its guests leave.	Medium7	IntervalsSimulation+2	No attempts yet	1s	512 MB	Judgeable
Graph Automata PlayerGiven a Boolean graph update rule and a state at time 0, decide whether a state at time -T exists and is unique, by inverting the adjacency matrix over GF(2).	Medium7	MatrixMath+1	No attempts yet	10s	512 MB	Judgeable
Comfortable StringCount how many substrings of a bracket string are both correctly balanced and symmetric under reversal with bracket swap.	Medium7	Dynamic programmingString+2	No attempts yet	1s	512 MB	Judgeable