Problems

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Total results29,455 problems

Height Order
Medium5
Graph, DFS+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Three Solutions
Medium5
Two pointers, Sorting+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Gems
Medium5
Array, Brute force+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Brotherly Field Division
Medium5
Dynamic programming, Brute force+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Inequality Signs
Medium5
Backtracking, Greedy+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Rotating Sushi
Medium5
Sliding window, Hash map+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Paramecia
Medium5
Dynamic programming, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Electric Wires
Medium5
Dynamic programming, Binary search+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Colored Paper 3
Medium5
Array, Brute force+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Folding a Tape Measure
Medium5
Simulation, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Crossing the Stone Bridges
Medium5
Dynamic programming, String
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Number Beads
Medium5
Binary search, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Finding the Middle Marble
Medium5
Graph, DFS+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cheese
Medium5
BFS, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Circuit Routing
Medium5
Shortest path, BFS+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Stable Group
Medium5
Union-find, Graph+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Corporate Investment
Medium5
Dynamic programming, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Making a Maze
Medium5
BFS, Shortest path+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Submarine Identification
Medium5
Dynamic programming, String matching+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Building EDSAC Instructions
Medium5
Bit manipulation, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Glass Balls
Medium5
Dynamic programming, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Running Medians
Medium5
Heap, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Adjacent Bit Pair Count
Medium5
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Normal Sort
Medium5
String, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Secret Message Decoder
Medium5
Matrix, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
A Margarita Today?
Medium5
Brute force, Recursion+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Minimum Cost for Restaurant Orders
Medium5
Greedy, Sorting+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Concert Tickets
Medium5
Greedy, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Jewelry Box
Medium5
Binary search, Greedy
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Remove Parentheses
Medium5
String, Bit manipulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cup Holder
Medium5
Greedy, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Digital TV
Medium5
Greedy, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Counting Sanggeun's Digit Friends
Medium5
Bit manipulation, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Knight
Medium5
BFS, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Viewership Popularity Survey
Medium5
Prefix sum, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Dongjun's Game
Medium5
Greedy, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Observing Two Stars
Medium5
Number theory, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Writing Numbers on Paper
Medium5
Math, Number theory+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Trimming Strings
Medium5
Binary search, String+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Restaurants
Medium5
Graph, DFS+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pleasant Word
Medium5
Dynamic programming, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Number Game
Medium5
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Table Rotation
Medium5
Simulation, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Vegetarian Pool Divider
Medium5
Geometry, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Array Not Divisible by Three
Medium5
Greedy, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Avogadro
Medium5
Greedy, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Word Search
Medium5
Trie, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Concert Rest Schedule
Medium5
Greedy, Intervals+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Counting Axis-Aligned Right Triangles
Medium5
Hash map, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tennis
Medium5
Simulation, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Triplets
Medium5
Geometry, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Peter Pan Frame
Medium5
Simulation, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Escape
Medium5
BFS, Matrix+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Debug
Medium5
Dynamic programming, Matrix+1
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Film Festival
Medium5
Combinatorics, Hash map+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Non-Intersecting Circles
Medium5
Greedy, Intervals+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Video Recommendations
Medium5
Binary search, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Beacon Network
Medium5
Simulation, Heap+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sangbeom's Secret Message
Medium5
String, Brute force+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sidewalk Pillars
Medium5
Greedy, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Alarm Clock
Medium5
Brute force, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Crane Delivery
Medium5
Graph, Union-find+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Handong Does Not Want to Study!
Medium5
Graph, DFS+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tomo's Calculator
Medium5
Math, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ball
Medium5
Simulation, Matrix+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Footnotes
Medium5
Dynamic programming, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cinema Invitation
Medium5
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Restoring a Scrambled Email
Medium5
String, Brute force+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
JANICA
Medium5
Simulation, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tram
Medium5
Shortest path, Graph+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
21 Rolls of Gimbap
Medium5
Simulation, Matrix+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Airplane
Medium5
Simulation, Queue+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Foot Typing
Medium5
Dynamic programming, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Truth-Tellers and Liars
Medium5
Brute force, Bit manipulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Safe Lock
Medium5
Sorting, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Exchange
Medium5
Dynamic programming, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cards
Medium5
Simulation, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
T9
Medium5
String, Hash map+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Friends Calling Plan
Medium5
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Popularity List
Medium5
Greedy, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cut and Paste
Medium5
Simulation, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
PIN
Medium5
Hash map, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Nasty Calculations
Medium5
Stack, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Printed Circuit Board
Medium5
Sorting, Binary search+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Matching Bins
Medium5
Binary search, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hop, Hop
Medium5
Math, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Coin
Medium5
Brute force, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ancient Manuscript
Medium5
Dynamic programming, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Linker
Medium5
Graph, BFS+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Gems
Medium5
Tree, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Grille
Medium5
Matrix, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
GoStack
Medium5
Stack, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Decoding Morse Sequences
Medium5
Dynamic programming, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Simple Arithmetic
Medium5
String, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Complete the Sequence!
Medium5
Math, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Labyrinth
Medium5
Graph, BFS+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Play on Words
Medium5
Graph, Union-find+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
ASCII Figure
Medium5
Geometry, Matrix+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Kingdom Roadmap
Medium5
Tree, Graph+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Reversible Lane
Medium5
Simulation, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Height OrderGiven pairwise shorter-than relations between students, count how many students have their exact height rank fully determined by transitivity.	Medium5	GraphDFS+1	No attempts yet	1s	128 MB	Judgeable
Three SolutionsGiven up to 5000 distinct integers, find three distinct values whose sum is closest to zero, using sorting and two-pointer scanning.	Medium5	Two pointersSorting+1	No attempts yet	1s	256 MB	Judgeable
GemsGiven up to 100 diamond points on a grid, find the position of a fixed-size K by K square (axis aligned, within map bounds) that covers the maximum number of diamonds.	Medium5	ArrayBrute force+1	No attempts yet	1s	128 MB	Judgeable
Brotherly Field DivisionChoose a non-decreasing staircase cut across N columns of an N x N grid to minimize the harvest difference between the two regions, and output one such cut.	Medium5	Dynamic programmingBrute force+1	No attempts yet	1s	256 MB	Judgeable
Inequality SignsGiven a sequence of < and > signs, place k+1 distinct digits 0-9 to satisfy all comparisons and output the lexicographically largest and smallest resulting digit strings.	Medium5	BacktrackingGreedy+1	No attempts yet	1s	256 MB	Judgeable
Rotating SushiFind the maximum distinct sushi types among any k consecutive plates on a circular belt, adding one bonus for a given coupon type if not already present.	Medium5	Sliding windowHash map+1	No attempts yet	1s	256 MB	Judgeable
ParameciaSimulate a population where each individual matures, reproduces daily within an age window, dies at a fixed age, and count survivors on day N modulo 1000.	Medium5	Dynamic programmingSimulation+1	No attempts yet	1s	128 MB	Judgeable
Electric WiresGiven wires connecting positions on two poles, find the minimum removals so remaining wires never cross, equivalent to n minus the longest increasing subsequence.	Medium5	Dynamic programmingBinary search+1	No attempts yet	1s	128 MB	Judgeable
Colored Paper 3Given up to 100 aligned black 10x10 squares on a 100x100 grid, find the maximum area axis-aligned all-black rectangle.	Medium5	ArrayBrute force+1	No attempts yet	1s	128 MB	Judgeable
Folding a Tape MeasureSimulate folding a tape at marked positions for red, blue, then yellow dot pairs, tracking coordinate transformations and final folded length.	Medium5	SimulationMath+1	No attempts yet	1s	128 MB	Judgeable
Crossing the Stone BridgesCount ways to match a scroll string to positions across two parallel bridge strings, alternating bridges and strictly increasing positions.	Medium5	Dynamic programmingString	No attempts yet	1s	128 MB	Judgeable
Number BeadsSplit an ordered array into M contiguous groups to minimize the largest group sum, then output that value and the group sizes.	Medium5	Binary searchGreedy+1	No attempts yet	1s	128 MB	Judgeable
Finding the Middle MarbleGiven pairwise heavier-than relations among N odd marbles, count marbles that must be eliminated as the possible median using transitive closure of the order.	Medium5	GraphDFS+1	No attempts yet	1s	128 MB	Judgeable
CheeseSimulate outside air spreading via BFS each hour to melt cheese cells touching air, and report total melting hours plus cheese count one hour before it fully disappears.	Medium5	BFSSimulation+1	No attempts yet	1s	128 MB	Judgeable
Circuit RoutingFind the minimum-cost grid path between two given cells where empty cells cost 1 and cells already occupied by given rectilinear circuits cost k, then output the path in compressed turn-point form.	Medium5	Shortest pathBFS+1	No attempts yet	1s	128 MB	Judgeable
Stable GroupGiven a like/dislike matrix, decide if people can be partitioned into groups (size at least 2) where members like each other within groups and dislike each other across groups, and output that partition.	Medium5	Union-findGraph+1	No attempts yet	1s	128 MB	Judgeable
Corporate InvestmentAllocate exactly N integer units of money across M companies using given profit tables to maximize total profit, then output an allocation, a classic knapsack-style DP task.	Medium5	Dynamic programmingArray+1	No attempts yet	1s	128 MB	Judgeable
Making a MazeFind the minimum number of black cells to convert to white so a path exists from top-left to bottom-right of an n x n grid, using 0-1 BFS or Dijkstra.	Medium5	BFSShortest path+1	No attempts yet	1s	128 MB	Judgeable
Submarine IdentificationDecide whether a binary string can be split into pieces of '01' or '1' followed by at least two 0s and at least one 1, using pattern matching or DP.	Medium5	Dynamic programmingString matching+1	No attempts yet	1s	128 MB	Judgeable
Building EDSAC InstructionsConvert a decimal fraction into two's-complement binary and print it as an EDSAC assembly instruction, rounding toward zero and detecting out-of-range values.	Medium5	Bit manipulationString+2	No attempts yet	1s	128 MB	Judgeable
Glass BallsGiven B balls and M floors, compute the minimum number of drops needed to guarantee finding the critical breaking floor in the worst case.	Medium5	Dynamic programmingMath+1	No attempts yet	1s	128 MB	Judgeable
Running MediansGiven a sequence read one number at a time, output the running median every time an odd number of elements have been read.	Medium5	HeapImplementation	No attempts yet	1s	128 MB	Judgeable
Adjacent Bit Pair CountCount binary strings of length n whose number of adjacent 11-pairs equals a given k, for up to 1000 queries.	Medium5	Dynamic programmingCombinatorics+1	No attempts yet	1s	128 MB	Judgeable
Normal SortImplement a custom string comparator that treats embedded numeric runs (with optional signs) by numeric value and letters case-insensitively, then compare pairs of strings accordingly.	Medium5	StringImplementation+1	No attempts yet	1s	128 MB	Judgeable
Secret Message DecoderReconstruct a matrix from a row-major binary string, read its cells in clockwise spiral order to recover 5-bit codes, and decode them back into the original letters and spaces.	Medium5	MatrixSimulation+1	No attempts yet	1s	128 MB	Judgeable
A Margarita Today?Count subsets of up to 30 prices whose sum is within budget D and whose leftover money cannot afford any unchosen item.	Medium5	Brute forceRecursion+1	No attempts yet	1s	128 MB	Judgeable
Minimum Cost for Restaurant OrdersGiven first-dish and later-dish prices for N dishes, compute for every k the minimum total cost of ordering exactly k dishes.	Medium5	GreedySorting+1	No attempts yet	2s	256 MB	Judgeable
Concert TicketsGiven which guys and girls hold tickets, output enter, exit, and ticket transfer actions so every girl leaves the venue while the number of guys with tickets inside is maximized.	Medium5	GreedySimulation+1	No attempts yet	1s	128 MB	Judgeable
Jewelry BoxGiven N children and piles of jewels per color, find the minimum possible maximum pile size when each color's jewels are split among some children.	Medium5	Binary searchGreedy	No attempts yet	1s	128 MB	Judgeable
Remove ParenthesesGiven an expression with up to 10 matching parenthesis pairs, output every distinct string formed by removing one or more full pairs, sorted lexicographically.	Medium5	StringBit manipulation+1	No attempts yet	1s	128 MB	Judgeable
Cup HolderGiven a seat row with regular seats and adjacent couple-seat pairs that lack a middle cup holder, compute the maximum number of people who can access a cup holder, matching people to holders one per holder.	Medium5	GreedyString+1	No attempts yet	1s	128 MB	Judgeable
Digital TVCompute the minimum button presses to move KBS1 to position 1 and KBS2 to position 2 in a channel list using arrow move and swap operations.	Medium5	GreedySimulation+1	No attempts yet	1s	128 MB	Judgeable
Counting Sanggeun's Digit FriendsGiven up to a million large integers, count pairs that share at least one decimal digit, requiring bitmask digit sets and efficient counting over 1024 subsets.	Medium5	Bit manipulationCombinatorics+1	No attempts yet	1s	128 MB	Judgeable
KnightSimulate a knight's moves on an N x N board for T steps (T up to a million), where each square can only be entered at time-multiples of its written value, and output all possible final squares.	Medium5	BFSSimulation+1	No attempts yet	1s	128 MB	Judgeable
Viewership Popularity SurveyGiven N viewing intervals (possibly wrapping past midnight) over a day, use a difference array over seconds to answer Q sum-of-popularity queries divided by interval length.	Medium5	Prefix sumArray+1	No attempts yet	1s	128 MB	Judgeable
Dongjun's GameGiven N level scores, find the minimum total decrease needed to make the sequence strictly increasing while all scores stay positive.	Medium5	GreedyArray+1	No attempts yet	1s	128 MB	Judgeable
Observing Two StarsGiven start times and periods of two blinking stars, find the earliest simultaneous blink time and weekday, or report it never happens.	Medium5	Number theoryMath+1	No attempts yet	1s	128 MB	Judgeable
Writing Numbers on PaperGiven a target average P (with up to 9 decimal digits) find the fewest sheets, each labeled 1 to 5, whose numbers average exactly P, and print the count of each value used.	Medium5	MathNumber theory+1	No attempts yet	1s	128 MB	Judgeable
Trimming StringsFind how many top rows can be removed one at a time from a grid while all column strings (read top to bottom) remain pairwise distinct.	Medium5	Binary searchString+1	No attempts yet	1s	256 MB	Judgeable
RestaurantsGiven a graph with up to 100000 nodes and edges, decide if edges can be 2-colored so every vertex of degree at least 2 sees both colors among its incident edges.	Medium5	GraphDFS+1	No attempts yet	1s	128 MB	Judgeable
Pleasant WordCount ways to fill blanks in a word with uppercase letters so it avoids three consecutive vowels or consonants and contains at least one 'L'.	Medium5	Dynamic programmingString+1	No attempts yet	1s	128 MB	Judgeable
Number GameAfter each new pair of numbers arrives, pair sorted A values with reverse sorted B values and output the minimum possible maximum sum, updating online for each round.	Medium5	GreedySorting+1	No attempts yet	1s	128 MB	Judgeable
Table RotationSimulate row and column rotations on an N x N table to move K numbers to given target cells in order, counting total rotations for each move.	Medium5	SimulationImplementation+1	No attempts yet	1s	128 MB	Judgeable
Vegetarian Pool DividerGiven one endpoint on the boundary of a fixed right isosceles triangle, compute the other endpoint of a segment that splits the triangle into two equal-area regions.	Medium5	GeometryMath+1	No attempts yet	1s	128 MB	Judgeable
Array Not Divisible by ThreeRearrange an array so no two adjacent elements sum to a multiple of 3, or report impossibility.	Medium5	GreedyMath+1	No attempts yet	1s	128 MB	Judgeable
AvogadroGiven a 3xN table where row 1 is a permutation of 1..N, find the minimum number of columns to delete so the three rows can be made identical after sorting each row.	Medium5	GreedyArray+1	No attempts yet	1s	128 MB	Judgeable
Word SearchGiven N database words compared in order against a query using character-by-character matching that also checks for word-end, compute total comparisons per query.	Medium5	TrieString+1	No attempts yet	1s	128 MB	Judgeable
Concert Rest ScheduleSchedule N members' fixed-length rest intervals within a T-minute concert so that at most two intervals overlap at any moment.	Medium5	GreedyIntervals+1	No attempts yet	1s	128 MB	Judgeable
Counting Axis-Aligned Right TrianglesCount triangles among N points where the right angle vertex has one point sharing its x-coordinate and another sharing its y-coordinate.	Medium5	Hash mapMath+1	No attempts yet	1s	128 MB	Judgeable
TennisValidate whether recorded tennis set scores form a legal best-of-three match, with a special rule that one named player never loses a set.	Medium5	SimulationImplementation+1	No attempts yet	1s	128 MB	Judgeable
TripletsGiven a grid with letters placed on some cells, count how many triples of letters are collinear.	Medium5	GeometryCombinatorics+1	No attempts yet	1s	128 MB	Judgeable
Peter Pan FrameDraw a 5-row banner where each letter of a word sits in a diamond of '#' or '*' depending on its position, with overlapping frames resolved by priority.	Medium5	SimulationString+1	No attempts yet	1s	128 MB	Judgeable
EscapeGiven a grid with rocks, spreading flood water, a start and a den, compute the minimum time for the hedgehog to reach the den using multi-source BFS for water and BFS for the hedgehog while comparing arrival times.	Medium5	BFSMatrix+1	No attempts yet	1s	128 MB	Judgeable
DebugGiven a binary R by C grid, find the largest square submatrix (side at least 2) that is invariant under 180-degree rotation, or output -1.	Medium5	Dynamic programmingMatrix+1	No attempts yet	5s	128 MB	Judgeable
Film FestivalGiven a bipartite graph of boat connections, count the number of pairs of left villages and pairs of right villages that form a complete K2,2 subgraph.	Medium5	CombinatoricsHash map+1	No attempts yet	1s	128 MB	Judgeable
Non-Intersecting CirclesGiven N circles centered on the x-axis, find the minimum number to remove so no two remaining circles overlap, essentially an interval scheduling problem.	Medium5	GreedyIntervals+1	No attempts yet	1s	128 MB	Judgeable
Video RecommendationsGiven a functional graph of K video recommendations and N starting nodes, find the node reached after exactly M-1 steps using binary lifting or cycle detection.	Medium5	Binary searchGraph+2	No attempts yet	1s	128 MB	Judgeable
Beacon NetworkSimulate beacons that light up over time and archers who shoot arrows down a fixed priority list toward unlit targets, computing each beacon's lighting time.	Medium5	SimulationHeap+1	No attempts yet	1s	128 MB	Judgeable
Sangbeom's Secret MessageGiven a Vigenere-style encrypted message and a known substring of the plaintext, deduce the repeating key and decrypt the full message.	Medium5	StringBrute force+1	No attempts yet	1s	128 MB	Judgeable
Sidewalk PillarsGiven a sidewalk string and up to N extra pillars, place pillars in free segments to minimize the count of length-L parking spots, breaking ties by using fewest pillars.	Medium5	GreedyString+1	No attempts yet	1s	128 MB	Judgeable
Alarm ClockGiven a target displayed time (hour mod 24, minute mod 60), find the four-digit keypad input with minimum total movement effort, breaking ties by earliest input.	Medium5	Brute forceMath+1	No attempts yet	1s	128 MB	Judgeable
Crane DeliveryGiven cranes with fixed positions and reach radii starting from a fixed entrance point, decide for each of K target points whether it lies in the union-reachability graph of overlapping crane discs starting from the entrance.	Medium5	GraphUnion-find+1	No attempts yet	1s	128 MB	Judgeable
Handong Does Not Want to Study!Given a functional graph where each node points to exactly one other node, find the starting node whose path visits the most distinct nodes before repeating, breaking ties by smallest index.	Medium5	GraphDFS+1	No attempts yet	1s	128 MB	Judgeable
Tomo's CalculatorGiven a calculator that repeatedly multiplies by B starting from A*B, find how many presses of '=' are needed until the displayed number ends with a given suffix C, or report impossible.	Medium5	MathSimulation+1	No attempts yet	1s	128 MB	Judgeable
BallSimulate rotating an N x N board with walls and a ball K times, letting gravity drop the ball each time, then print the final board.	Medium5	SimulationMatrix+1	No attempts yet	1s	128 MB	Judgeable
FootnotesGiven text lines and footnotes attached to specific lines, compute the minimum number of pages so that each page holds consecutive text lines plus their footnotes within a line limit K.	Medium5	Dynamic programmingGreedy+1	No attempts yet	1s	128 MB	Judgeable
Cinema InvitationGiven each friend's minimum required number of other attending friends, find the smallest subset size satisfying everyone invited's threshold.	Medium5	GreedySorting+1	No attempts yet	1s	128 MB	Judgeable
Restoring a Scrambled EmailGiven a scrambled string formed by replacing '@' with 'at' and optionally inserting 'nospam' once, output all distinct valid email addresses that could produce it.	Medium5	StringBrute force+1	No attempts yet	1s	128 MB	Judgeable
JANICAReconstruct running leader times from cumulative differences over two ski rounds to find the top three finishers by total time.	Medium5	SimulationSorting+1	No attempts yet	1s	128 MB	Judgeable
TramFind the minimum number of switch changes needed to travel from intersection A to B in a directed graph where each node's first listed edge is free and others cost 1, using shortest-path with 0/1 edge weights.	Medium5	Shortest pathGraph+1	No attempts yet	1s	128 MB	Judgeable
21 Rolls of GimbapSimulate a Connect Four style game on a 6x7 board from 21 alternating moves and report who first got four in a row and on which of their throws.	Medium5	SimulationMatrix+1	No attempts yet	1s	128 MB	Judgeable
AirplaneSimulate passengers walking down a single aisle to their assigned row and taking 5 seconds to load luggage, blocked by others ahead, to find total boarding time.	Medium5	SimulationQueue+1	No attempts yet	1s	128 MB	Judgeable
Foot TypingGiven two words and their interleaving, output the lexicographically smallest sequence of 1s and 2s marking which word produced each character.	Medium5	Dynamic programmingString+1	No attempts yet	1s	128 MB	Judgeable
Truth-Tellers and LiarsCount all ways to label N people as truth-tellers or liars so that every statement matches the truth-and-lies rule.	Medium5	Brute forceBit manipulation+1	No attempts yet	1s	128 MB	Judgeable
Safe LockGiven N positions on a circular ring of size 10,000,000, find the minimum total distance to move all points to a common position, minimizing sum of circular distances.	Medium5	SortingPrefix sum+2	No attempts yet	1s	128 MB	Judgeable
ExchangeGiven daily buy and sell exchange rates between marks and dollars, compute the maximum marks obtainable after N days starting from 100 marks, output as a reduced fraction.	Medium5	Dynamic programmingMath+1	No attempts yet	1s	128 MB	Judgeable
CardsSimulate a card-sorting game to find which numbers remain consistent with a sequence of column answers after repeated row/column reshuffling.	Medium5	SimulationMath	No attempts yet	1s	128 MB	Judgeable
T9Simulate a T9 keypad predictor that maps key-press sequences to dictionary words, splitting on key 1 as space and marking unmatched words with asterisks.	Medium5	StringHash map+1	No attempts yet	1s	128 MB	Judgeable
Friends Calling PlanGiven call minutes between up to 16 employees, pair them all up to minimize total billing cost using bitmask DP over perfect matchings.	Medium5	Dynamic programmingBit manipulation+1	No attempts yet	1s	128 MB	Judgeable
Popularity ListReconstruct the lexicographically smallest previous week's ranking consistent with UP/DOWN/SAME movement marks of this week's list.	Medium5	GreedyArray+1	No attempts yet	1s	128 MB	Judgeable
Cut and PasteSimulate K cut-and-paste block moves on an N-line document and report the first ten resulting line values.	Medium5	SimulationArray+1	No attempts yet	1s	128 MB	Judgeable
PINCount pairs of 4-character PINs (from a given list) that differ in exactly D of their four positions.	Medium5	Hash mapCombinatorics+1	No attempts yet	1s	128 MB	Judgeable
Nasty CalculationsEvaluate a postfix arithmetic formula modulo B for up to 100000 given base-B values of x and print only the last digit each time.	Medium5	StackMath+1	No attempts yet	1s	128 MB	Judgeable
Printed Circuit BoardGiven N wires each connecting a bottom-edge point to a top-edge point, find the minimum number of layers so that crossing wires never share a layer, which reduces to finding the maximum count of pairwise-crossing wires.	Medium5	SortingBinary search+1	No attempts yet	1s	128 MB	Judgeable
Matching BinsGiven a sequence of bin sizes, find the largest K such that the first K bins can each be matched to a distinct larger bin among the following K bins.	Medium5	Binary searchGreedy+1	No attempts yet	1s	128 MB	Judgeable
Hop, HopCount, modulo 1000000, the number of ways to write n as a non-increasing sequence of jumps of length 1, 2, or 3, for n up to 1e9.	Medium5	MathDynamic programming+1	No attempts yet	1s	128 MB	Judgeable
CoinDetermine the fake coin among 12 and whether it is heavier or lighter, given three balance weighing results, or report impossible/indefinite.	Medium5	Brute forceSimulation+1	No attempts yet	1s	128 MB	Judgeable
Ancient ManuscriptCount ways to fill '*' letters in a word so runs of vowels/consonants respect maximum length and maximum equal-letter-repeat limits, using DP over letter classes and previous letter identity.	Medium5	Dynamic programmingString+1	No attempts yet	1s	128 MB	Judgeable
LinkerGiven modules with export/import tables and an entry symbol, find the reachable non-redundant modules, duplicate exports used by them, and unresolved imports.	Medium5	GraphBFS+1	No attempts yet	1s	128 MB	Judgeable
GemsGiven a tree, assign positive integer prices to vertices so adjacent vertices differ, minimizing total sum, essentially a greedy coloring based on tree structure.	Medium5	TreeGreedy+1	No attempts yet	1s	128 MB	Judgeable
The GrilleSimulate reading letters through the four rotations of a grille cipher grid to recover the plaintext for each test case.	Medium5	MatrixSimulation+1	No attempts yet	1s	128 MB	Judgeable
GoStackSimulate a custom stack-based virtual machine with arithmetic operations and specific division rules, detecting errors and printing results for many inputs.	Medium5	StackSimulation+1	No attempts yet	1s	128 MB	Judgeable
Decoding Morse SequencesCount the number of ways to split a given Morse code string into a sequence of dictionary words, using dynamic programming with Morse-to-word conversion.	Medium5	Dynamic programmingString+1	No attempts yet	1s	128 MB	Judgeable
Simple ArithmeticSimulate long addition, subtraction, and multiplication of big numbers, printing the numbers and partial products aligned like on paper.	Medium5	StringSimulation+1	No attempts yet	1s	128 MB	Judgeable
Complete the Sequence!Given a sequence known to fit a minimal-degree polynomial, use finite differences to extrapolate the next several integer values exactly.	Medium5	MathImplementation+1	No attempts yet	1s	128 MB	Judgeable
LabyrinthGiven a grid maze that forms a tree of free cells, compute the diameter (longest path in number of steps) between any two free cells.	Medium5	GraphBFS+1	No attempts yet	1s	256 MB	Judgeable
Play on WordsDetermine whether all given words can be chained into one sequence where each word's first letter matches the previous word's last letter, using Eulerian path conditions on a letter graph.	Medium5	GraphUnion-find+1	No attempts yet	1s	256 MB	Judgeable
ASCII FigureGiven a grid picture drawn with '.', '/', and '\' forming one closed polygon from diagonal cell segments, compute the polygon's area.	Medium5	GeometryMatrix+1	No attempts yet	1s	128 MB	Judgeable
Kingdom RoadmapGiven a tree, compute the minimum number of extra edges needed so the graph stays connected after any single edge removal, which equals the number of leaves divided by two, rounded up.	Medium5	TreeGraph+1	No attempts yet	2s	128 MB	Judgeable
Reversible LaneSimulate traffic queues on a reversible bridge lane over all possible switch times to find the switch time minimizing total waiting cars.	Medium5	SimulationPrefix sum+1	No attempts yet	1s	128 MB	Judgeable