Problems

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Total results29,441 problems

Stacking Sticks
Medium5
Segment tree, Sorting+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Riddle of the Sphinx
Medium5
Math, Brute force+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Binary Grid
Medium5
Dynamic programming, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Dihedral Group
Medium5
String matching, Array
No attempts yet
Time limit
1s
Memory limit
2048 MB
Judgeable
2024
Medium5
Dynamic programming, String
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sudoku
Medium5
Array, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
September
Medium5
Tree, Array+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Tightly Packed
Medium5
Math, Brute force
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
A Bug That's Not a Pill Bug
Medium5
Simulation, Hash map+1
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Magical Barrier
Medium5
Geometry, Brute force
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Nightmare Brother
Medium5
Brute force, String+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
The Only Mode
Medium5
Prefix sum, Hash map+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Street Lamps
Medium5
Heap, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Button Pressing
Medium5
String, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Merge Not Sort
Medium5
Greedy, Array+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Roller Coaster 2
Medium5
Array, Greedy+1
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
City Tour
Medium5
Dynamic programming, Bit manipulation
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Infinite Race
Medium5
Array, Simulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Hiring Workers
Medium5
Prefix sum, Hash map+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Rock-Paper-Scissors
Medium5
Hash map, String
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Heater on the Farm
Medium5
Binary search, Array+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Card Game (Hard)
Medium5
Greedy, Binary search+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Moving Freely
Medium5
Binary search, Math+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Password
Medium5
Dynamic programming, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Chukjibeop
Medium5
Graph, BFS
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
a11y
Medium5
String, Bit manipulation+1
No attempts yet
Time limit
3.5s
Memory limit
1024 MB
Judgeable
Complete Binary Tree and Queries
Medium5
Math, Tree+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Communication System Performance Degradation
Medium5
Brute force, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Baseball
Medium5
Sorting, Binary search+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Mountain
Medium5
Array, Two pointers
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Square Dream
Medium5
Hash map, Geometry+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Code Master, Sliding Puzzle Master, Board Game Master
Medium5
Game theory, Bit manipulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Consecutive lectures are hard (Easy)
Medium5
Dynamic programming, Prefix sum
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Wonderland Sundew
Medium5
Greedy, Intervals+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Super Shy (Easy)
Medium5
Dynamic programming, Greedy
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Finding the Counterfeit Coin
Medium5
Math, Implementation
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Random Multi-Match
Medium5
String, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Secret of the Sequence (Hard)
Medium5
Divide and conquer, Recursion+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Max-Queen
Medium5
Math, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Income Inequality
Medium5
Sorting, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Rectangular Dry Land
Medium5
Matrix, Stack+1
No attempts yet
Time limit
7s
Memory limit
1024 MB
Judgeable
Weekend Gardening
Medium5
Dynamic programming, Probability
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Fixing the Tournament
Medium5
Math, Greedy
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Speed Ups
Medium5
Dynamic programming, Sorting
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Team Work
Medium5
Dynamic programming, Brute force
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Please Please Please
Medium5
Brute force, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
I Am Going to Get Rich!
Medium5
Greedy, String+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Harmony
Medium5
Dynamic programming, Array
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Daedong Yeojido Roads
Medium5
Minimum spanning tree, Union-find+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sour Face
Medium5
String, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
I Want to Turn Back Time
Medium5
Binary search, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Deck Operations and Queries
Medium5
Tree, Stack+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Keunseong, Get to Work
Medium5
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Too Hot!
Medium5
BFS, Graph+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Gift Selection
Medium5
Greedy, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Fireworks
Medium5
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Charging
Medium5
Segment tree, Implementation+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Hitting the Targets
Medium5
Combinatorics, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Things Got Out of Hand
Medium5
Greedy, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Staircase Sequences and Queries
Medium5
Segment tree, Array
No attempts yet
Time limit
2.5s
Memory limit
1024 MB
Judgeable
Treasure Hunt
Medium5
Graph, Shortest path
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Citizenship
Medium5
Prefix sum, Simulation
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Business Magic
Medium5
Array, Dynamic programming
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Disbursement on Quarantine Policy
Medium5
Probability, Brute force+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Make RUN Great Again
Medium5
Binary search, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Interference
Medium5
Prefix sum, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
WALK
Medium5
Dynamic programming, Graph+1
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
TOLLS
Medium5
Union-find, Sorting+1
No attempts yet
Time limit
0.25s
Memory limit
1024 MB
Judgeable
Menger Sponge
Medium5
Math, Recursion
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Rhythm Flow
Medium5
Dynamic programming, Array
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Palindrome Check 2
Medium5
String, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Grade Conversion 2
Medium5
Prefix sum, Greedy
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Soul Escape from Rough Blocks
Medium5
Math, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Raehwan's Course Registration
Medium5
Bit manipulation, Hash map+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Skokovi
Medium5
Dynamic programming, Segment tree
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Giganotosaurus Game
Medium5
Dynamic programming, Array+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Investment Investigation
Medium5
Heap, Simulation+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Finding Suspicious Proteins
Medium5
Greedy, Array+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Inconsistent Patterns
Medium5
Math, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Horrendous Mistake
Medium5
Array, Hash map+1
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Jailbreak
Medium5
Graph, BFS+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Buggy Blinkers
Medium5
BFS, Graph+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Interrail Pass
Medium5
Dynamic programming, Binary search
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Museum Visit
Medium5
Dynamic programming, Intervals+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Hunting the Mavericks
Medium5
Prefix sum, Array
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Card Flipping Game
Medium5
Array, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
One-Sided Love
Medium5
Graph, DFS
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Partition
Medium5
Array, Number theory+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Two Stacks
Medium5
Prefix sum, Two pointers+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
A_i \times A_j
Medium5
Array, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Two Decks
Medium5
Prefix sum, Brute force+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Goldbach Heukheuk's Conjecture
Medium5
Divide and conquer, Hash map+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
The Labyrinth with Changing Exits
Medium5
Graph, Shortest path+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Find the Root of the Tree
Medium5
Tree, DFS
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Enchanted Maze
Medium5
BFS, Simulation+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Guard Evaders
Medium5
Brute force, Simulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Jigsaw Puzzle
Medium5
Math, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Clearing the Track
Medium5
Math, Simulation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Making a Sequence
Medium5
Prefix sum, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Grades
Medium5
Matrix, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Stacking SticksDrop 1x4 horizontal and 4x1 vertical blocks onto columns, then report the highest block height at a given x coordinate.	Medium5	Segment treeSorting+1	No attempts yet	1s	512 MB	Judgeable
Riddle of the SphinxAsk the sphinx five total-leg queries to find the leg counts of an axex, a basilisk, and a centaur, knowing one of the five answers may be false.	Medium5	MathBrute force+1	No attempts yet	2s	1024 MB	Judgeable
Binary GridFind the largest binary number spelled by the digits along a right-or-down path from the top-left to the bottom-right of a 0/1 grid.	Medium5	Dynamic programmingGreedy+1	No attempts yet	1s	1024 MB	Judgeable
Dihedral GroupCheck whether the sequence t appears as a contiguous block in some rotation or reflection of the circular labeling d.	Medium5	String matchingArray	No attempts yet	1s	2048 MB	Judgeable
2024Decide whether a digit string can be built from English digit words, where each word is either a digit or a repeat count for the next word's digit.	Medium5	Dynamic programmingString	No attempts yet	1s	1024 MB	Judgeable
SudokuAfter each of M writes into an N^2 by N^2 grid, print 1 if the grid is a valid sudoku with special squares, otherwise print 0.	Medium5	ArrayImplementation	No attempts yet	2s	1024 MB	Judgeable
SeptemberGiven M recorded orders of leaf deletions in a rooted tree, find the largest K such that all records agree on which nodes fall on each of the K days.	Medium5	TreeArray+1	No attempts yet	1s	1024 MB	Judgeable
Tightly PackedGiven N widgets, find the fewest empty cells in a W by H box with H/2 <= W <= 2H that holds all N widgets.	Medium5	MathBrute force	No attempts yet	1s	1024 MB	Judgeable
A Bug That's Not a Pill BugSimulate a bug that turns left at obstacles and find its lattice position after it moves exactly d steps, where d can reach 10^18.	Medium5	SimulationHash map+1	No attempts yet	8s	1024 MB	Judgeable
Magical BarrierGiven N points with no three collinear, find the maximum number of other complete segments between point pairs that cross a single segment.	Medium5	GeometryBrute force	No attempts yet	2s	1024 MB	Judgeable
Nightmare BrotherGiven N hints placing substrings in a length-M string, with at most one hint false, print the unique possible string, -1 if none exists, or -2 if several do.	Medium5	Brute forceString+1	No attempts yet	2s	1024 MB	Judgeable
The Only ModeGiven an array of values 0 to 3, find for each value the longest subarray in which that value occurs strictly more often than any other value, or report 0 if none exists.	Medium5	Prefix sumHash map+1	No attempts yet	2s	1024 MB	Judgeable
Street LampsGiven lamp positions on a line, list the K smallest distances from integer positions 0 to L to the nearest lamp, in increasing order.	Medium5	HeapSorting+1	No attempts yet	2s	1024 MB	Judgeable
Button PressingGiven initial lamp states A and target states B, decide whether pressing buttons that flip neighboring lamps (only when the button's own lamp is on) can reach B.	Medium5	StringGreedy+1	No attempts yet	2s	1024 MB	Judgeable
Merge Not SortSplit a permutation of 1 to 2N into two length-N arrays A and B so that the merge routine outputs it, or report -1 if no split works.	Medium5	GreedyArray+1	No attempts yet	2s	1024 MB	Judgeable
Roller Coaster 2Given groups in a line for a coaster with capacity M, find the fewest runs after swapping at most one pair of adjacent groups.	Medium5	ArrayGreedy+1	No attempts yet	8s	1024 MB	Judgeable
City TourFind the minimum and maximum time of a tour from city 1 that visits every city once and uses each transportation means exactly once.	Medium5	Dynamic programmingBit manipulation	No attempts yet	2s	512 MB	Judgeable
Infinite RaceGiven overtaking events between Anika and other runners on a circular track, find the fewest finish line crossings Anika must have made.	Medium5	ArraySimulation	No attempts yet	1s	1024 MB	Judgeable
Hiring WorkersCount contiguous groups of workers with equal numbers of task 1 and task 2 workers whose efficiency sums differ by at most K.	Medium5	Prefix sumHash map+1	No attempts yet	2s	1024 MB	Judgeable
Rock-Paper-ScissorsFind the fewest rounds in which Pidol's moves leave between 1 and K friends, and print the moves that achieve it.	Medium5	Hash mapString	No attempts yet	1s	1024 MB	Judgeable
Heater on the FarmGiven N cows in a line with frozen degrees a_j, place one heater on a cow so the largest a_j times its distance to the heater is as small as possible, and print that value.	Medium5	Binary searchArray+1	No attempts yet	2s	1024 MB	Judgeable
Card Game (Hard)Given health H and a set of attack values that grows by one card per query, find the fewest cards whose attacks sum to at least H, or -1 if impossible.	Medium5	GreedyBinary search+1	No attempts yet	1s	1024 MB	Judgeable
Moving FreelyGiven obstacles on a number line, count the positions Huynh can reach after T one-meter moves from P without stepping on an obstacle.	Medium5	Binary searchMath+1	No attempts yet	4s	1024 MB	Judgeable
PasswordGiven the 1-bit count of each of N numbers in the range 1 to M, find the sequence of numbers with the most adjacent pairs differing by 1, breaking ties lexicographically.	Medium5	Dynamic programmingImplementation	No attempts yet	1s	1024 MB	Judgeable
ChukjibeopGiven M roads among N locations, find the minimum time from s to e for each query, where a 1-minute teleport may only reach locations not connected by roads.	Medium5	GraphBFS	No attempts yet	2s	1024 MB	Judgeable
a11yGiven a string A and queries of the form letter, k, letter, count the substrings of A that start with the first letter, end with the second, and have length k+2.	Medium5	StringBit manipulation+1	No attempts yet	3.5s	1024 MB	Judgeable
Complete Binary Tree and QueriesGiven a complete binary tree with N vertices and a movable root, answer queries for the sum of vertex numbers in the subtree of v under the current root.	Medium5	MathTree+1	No attempts yet	3s	1024 MB	Judgeable
Communication System Performance DegradationGiven a grid with one base station and M nodes, find the largest value of path loss minus bounding box area when exactly K1 nodes (day) or K2 nodes (night) are activated.	Medium5	Brute forceGreedy+1	No attempts yet	1s	1024 MB	Judgeable
BaseballGiven batted ball positions and candidate fence radii, count the foul balls, infield balls, and home runs for each radius.	Medium5	SortingBinary search+1	No attempts yet	1s	1024 MB	Judgeable
MountainCount the contiguous subarrays that never decrease before a peak and never increase after it, with N up to 500000.	Medium5	ArrayTwo pointers	No attempts yet	1s	1024 MB	Judgeable
Square DreamGiven N scalene triangles, decide whether two of them can be glued along equal-length sides to form a simple quadrilateral.	Medium5	Hash mapGeometry+1	No attempts yet	1s	1024 MB	Judgeable
Code Master, Sliding Puzzle Master, Board Game MasterGiven a piece at (r,c) on a huge grid where each move lowers the row or the column, decide whether the first player wins and give a winning first move.	Medium5	Game theoryBit manipulation	No attempts yet	1s	1024 MB	Judgeable
Consecutive lectures are hard (Easy)Count the timetables that include every mandatory period and whose longest run of consecutive chosen periods is exactly k, modulo 1e9+7.	Medium5	Dynamic programmingPrefix sum	No attempts yet	1s	1024 MB	Judgeable
Wonderland SundewDecide whether a fly starting at (0,0) can reach (N,0) in N steps, where each step drops at most 1, while staying above or below given sundew tips.	Medium5	GreedyIntervals+1	No attempts yet	1s	1024 MB	Judgeable
Super Shy (Easy)Given N seats, people sit one at a time, each taking a seat that maximizes the distance to the nearest seated person. Find the largest number of people who can be seated.	Medium5	Dynamic programmingGreedy	No attempts yet	1s	1024 MB	Judgeable
Finding the Counterfeit CoinFind the lighter counterfeit among N coins using at most 5 interactive two-pan balance weighings, where each weighing reports left lighter, right lighter, or equal.	Medium5	MathImplementation	No attempts yet	0.5s	512 MB	Judgeable
Random Multi-MatchGiven a cyclic A/B string, sum the number of games each best-of-g match plays, starting from position s and wrapping around the board games.	Medium5	StringPrefix sum+1	No attempts yet	2s	512 MB	Judgeable
Secret of the Sequence (Hard)Given a sequence where a_2i and a_2i+1 are linear functions of a_i, find the sum of the first 2^k-1 terms modulo 1e9+7.	Medium5	Divide and conquerRecursion+1	No attempts yet	1s	1024 MB	Judgeable
Max-QueenPlace queens on an n by m board to maximize the number of attacking pairs, where a queen blocked by another queen does not attack past it.	Medium5	MathImplementation	No attempts yet	2s	1024 MB	Judgeable
Income InequalityGiven n household wealth values, find the maximum of y minus x, where the top x percent of households hold y percent of total wealth.	Medium5	SortingPrefix sum+1	No attempts yet	2s	1024 MB	Judgeable
Rectangular Dry LandGiven a binary grid of wet and dry cells, find the area of the largest rectangle made only of dry cells.	Medium5	MatrixStack+1	No attempts yet	7s	1024 MB	Judgeable
Weekend GardeningFind the probability that buying plants one at a time, each drawn from the remaining stock, keeps the running total within the budget range from L to H.	Medium5	Dynamic programmingProbability	No attempts yet	1s	1024 MB	Judgeable
Fixing the TournamentGiven n and your team's rank r in a bracket of 2^n single-elimination teams, find the latest round your team can reach when you choose every pairing.	Medium5	MathGreedy	No attempts yet	1s	1024 MB	Judgeable
Speed UpsGiven speed-up boosts at fixed meter marks, find the fastest finishing time when a taken boost blocks any other boost until it ends.	Medium5	Dynamic programmingSorting	No attempts yet	2s	1024 MB	Judgeable
Team WorkGiven n students with per-problem solve times and a total contest time, find the most problems the team can solve when each student solves at most one and problems run one at a time.	Medium5	Dynamic programmingBrute force	No attempts yet	1s	1024 MB	Judgeable
Please Please PleaseGiven each student's score, requested letter, and please count, choose A, B, C, and D cutoffs that satisfy the most high-please students first, then maximize the cutoffs in order.	Medium5	Brute forcePrefix sum+1	No attempts yet	2s	1024 MB	Judgeable
I Am Going to Get Rich!Given N dial digits, find the smallest resulting number after exactly M turns, where each turn adds 1 to one digit modulo 10.	Medium5	GreedyString+1	No attempts yet	1s	1024 MB	Judgeable
HarmonyChoose trainings within time N to maximize energy, doubling it when the harmony sum is 0, then print that harmony sum and energy.	Medium5	Dynamic programmingArray	No attempts yet	2s	1024 MB	Judgeable
Daedong Yeojido RoadsBuild a minimum-cost road network that connects all places, breaking cost ties by road-type priority, and report the count and cost of each road type.	Medium5	Minimum spanning treeUnion-find+2	No attempts yet	1s	1024 MB	Judgeable
Sour FaceCount the coin-flip sequences that trim characters from both ends until the remaining string is k '>' characters followed by k '<' characters, modulo 10^9 + 7.	Medium5	StringCombinatorics+1	No attempts yet	1s	1024 MB	Judgeable
I Want to Turn Back TimeGiven N days and a powered-on array A, find the minimum T so that at most K jumps of T days back, each taken on a powered day, get you from day N to day 1.	Medium5	Binary searchDynamic programming+1	No attempts yet	1s	1024 MB	Judgeable
Deck Operations and QueriesProcess N deck actions (push, pop, restore to an earlier action's state, print the card sum) and output the sum for each print.	Medium5	TreeStack+1	No attempts yet	2s	1024 MB	Judgeable
Keunseong, Get to WorkTrash is added at tree coordinates, and each clear query walks to the nearest remaining tree, with ties going to the smaller coordinate. Output the total distance walked.	Medium5	GreedySorting+1	No attempts yet	1s	1024 MB	Judgeable
Too Hot!Find the fewest moves from house S to meeting place E on a grid where discomfort rises outdoors, falls indoors, and must stay below 100.	Medium5	BFSGraph+1	No attempts yet	1s	1024 MB	Judgeable
Gift SelectionGiven gift sizes, box sizes, and the boxes taken by K earlier winners, find the largest gift you can take from the largest remaining box over all valid assignments.	Medium5	GreedySorting+1	No attempts yet	2s	1024 MB	Judgeable
FireworksGiven firecracker brilliances and a threshold K, find the most shows you can build from single or paired firecrackers, each at least K and in non-decreasing order.	Medium5	GreedySorting+1	No attempts yet	1s	1024 MB	Judgeable
ChargingEach plug request takes the smallest empty port numbered at least i, and each unplug query reports which action filled that port.	Medium5	Segment treeImplementation+1	No attempts yet	2s	1024 MB	Judgeable
Hitting the TargetsCount the shooting orders that hit all N targets, where each shot takes the top or bottom target of one string, modulo 10^9+7.	Medium5	CombinatoricsMath	No attempts yet	1s	1024 MB	Judgeable
Things Got Out of HandArrange 1 to N in a permutation so that multiplying at odd positions and adding at even positions gives the largest final value of X, starting from 1.	Medium5	GreedyImplementation	No attempts yet	1s	1024 MB	Judgeable
Staircase Sequences and QueriesGiven a sequence with range additions, answer queries for the longest run of adjacent differences equal to k within a given range.	Medium5	Segment treeArray	No attempts yet	2.5s	1024 MB	Judgeable
Treasure HuntFor each island x, find the maximum of v_y minus the cheapest sea route cost from x to any island y.	Medium5	GraphShortest path	No attempts yet	4s	1024 MB	Judgeable
CitizenshipGiven the dates you were abroad, find the earliest application date where each of the last y 365-day periods includes at least d days in the country.	Medium5	Prefix sumSimulation	No attempts yet	4s	1024 MB	Judgeable
Business MagicPick one interval to double, and negate each negative store outside it, to maximize the total profit for next month.	Medium5	ArrayDynamic programming	No attempts yet	2s	1024 MB	Judgeable
Disbursement on Quarantine PolicyGiven a seat grid with known infections and 50% uncertain ones, find the expected total quarantine days modulo 1e9+7.	Medium5	ProbabilityBrute force+1	No attempts yet	2s	1024 MB	Judgeable
Make RUN Great AgainFind the lowest starting score for club N+1 that ranks it at most X after lowering other clubs' scores, with total skepticism cost under K.	Medium5	Binary searchGreedy+1	No attempts yet	1s	1024 MB	Judgeable
InterferenceEach wave adds a period-4 pattern of +a and -a over an interval, and each query asks for the summed height at one position.	Medium5	Prefix sumMath+1	No attempts yet	1s	1024 MB	Judgeable
WALKGiven streets each with a recorded traversal time, find the longest walk from crossroad 1 to every crossroad where the times strictly increase.	Medium5	Dynamic programmingGraph+1	No attempts yet	1.5s	1024 MB	Judgeable
TOLLSFor each query [l, r], sum the costs of all city pairs whose path's largest toll falls in [l, r], where the cost is that largest toll.	Medium5	Union-findSorting+1	No attempts yet	0.25s	1024 MB	Judgeable
Menger SpongeGiven a level L and a point with rational coordinates, decide whether the point lies in the level-L Menger sponge.	Medium5	MathRecursion	No attempts yet	2s	1024 MB	Judgeable
Rhythm FlowMatch expected and actual presses in order, each at most once, to maximize the total points, where each pair scores 7, 6, 4, 2, or 0 based on the time gap.	Medium5	Dynamic programmingArray	No attempts yet	1s	1024 MB	Judgeable
Palindrome Check 2Given a string with some unknown positions, find the fewest adaptive queries asking whether position i holds letter c that are needed to decide if the string is a palindrome.	Medium5	StringMath+1	No attempts yet	1s	1024 MB	Judgeable
Grade Conversion 2Given the new grades b, recover old grades a that produce them under the averaging rule, or print -1 if no such sequence exists.	Medium5	Prefix sumGreedy	No attempts yet	2s	1024 MB	Judgeable
Soul Escape from Rough BlocksGiven N blocks in a row, repeatedly remove blocks from chains of length 3 or more, keeping the new chains as long as possible. Find the maximum blocks removed for N up to 1e18.	Medium5	MathGreedy+1	No attempts yet	1s	1024 MB	Judgeable
Raehwan's Course RegistrationGiven each student's enrollments in S_1 to S_{N-1}, count the subsets of students for S_N that keep every student's course set nonempty and distinct.	Medium5	Bit manipulationHash map+1	No attempts yet	1s	1024 MB	Judgeable
SkokoviGiven flower heights and a limit K, mark which flowers a grasshopper can reach from the first one by jumping only rightward to flowers whose height differs by at most K.	Medium5	Dynamic programmingSegment tree	No attempts yet	5s	1024 MB	Judgeable
Giganotosaurus GameCount the ways to cross a row of n cells with cactus obstacles, moving one cell right or jumping over k cells on the kth jump, modulo 1e9+7.	Medium5	Dynamic programmingArray+1	No attempts yet	1s	1024 MB	Judgeable
Investment InvestigationSimulate a buy and sell order book with normal and fill-or-kill orders, and list every trade as sell index, buy index, and amount.	Medium5	HeapSimulation+1	No attempts yet	4s	1024 MB	Judgeable
Finding Suspicious ProteinsGiven n embeddings of length l under Manhattan distance, pick k proteins greedily by farthest-point selection and print their identifiers in order.	Medium5	GreedyArray+1	No attempts yet	2s	1024 MB	Judgeable
Inconsistent PatternsGiven N categories and a total of M attempts per team, build per-category solve counts so team X wins every category but team Y has the higher overall success rate.	Medium5	MathImplementation	No attempts yet	2s	1024 MB	Judgeable
Horrendous MistakeAfter each point update to an array, report the sum of a[x] over every value x in the array, which is the buggy function's output.	Medium5	ArrayHash map+1	No attempts yet	8s	1024 MB	Judgeable
JailbreakGiven a jail grid with ceiling holes and ladders, decide whether the prisoner can climb from the bottom-left cell to the top storey exits.	Medium5	GraphBFS+1	No attempts yet	2s	1024 MB	Judgeable
Buggy BlinkersFind the shortest route from intersection 1 to intersection n when the blinkers can be switched on at most k times and each turn needs its matching blinker.	Medium5	BFSGraph+1	No attempts yet	4s	1024 MB	Judgeable
Interrail PassGiven travel days with individual fares and pass types that cover the first d travel days of a p-day window, find the minimum total cost to cover all travel days.	Medium5	Dynamic programmingBinary search	No attempts yet	1s	1024 MB	Judgeable
Museum VisitChoose visit days with the smallest total discomfort so that every exhibition's day range contains at least one chosen day.	Medium5	Dynamic programmingIntervals+1	No attempts yet	4s	1024 MB	Judgeable
Hunting the MavericksChoose a starting level on a circle of n levels so that the number of armour upgrades whose unlock weapon is obtained after the upgrade's level is minimized.	Medium5	Prefix sumArray	No attempts yet	1s	1024 MB	Judgeable
Card Flipping GameGiven N cards with colors 0 or 1, flip the prefix of cards 1 through X at most once to find the longest run of equal colors.	Medium5	ArrayPrefix sum+1	No attempts yet	1s	1024 MB	Judgeable
One-Sided LoveFor each node x other than 1, decide whether two paths from node 1 to x share no node besides 1 and x, and output a binary string.	Medium5	GraphDFS	No attempts yet	2s	1024 MB	Judgeable
PartitionGiven an integer array, decide whether it can be cut into equal-length contiguous segments (each shorter than N) where every segment has the same minimum plus maximum.	Medium5	ArrayNumber theory+1	No attempts yet	1s	1024 MB	Judgeable
Two StacksGiven two stacks of item weights, remove at most K top items in total to minimize the weight of the heavier remaining backpack.	Medium5	Prefix sumTwo pointers+1	No attempts yet	1s	1024 MB	Judgeable
A_i \times A_jGiven an array, pick two different elements, replace both with their product, and find the maximum array sum possible with at most one such operation.	Medium5	ArraySorting+2	No attempts yet	1s	1024 MB	Judgeable
Two DecksWonbin removes at most K items from the top or bottom of two stacks to minimize the weight of the heavier backpack he is left carrying.	Medium5	Prefix sumBrute force+1	No attempts yet	1s	1024 MB	Judgeable
Goldbach Heukheuk's ConjectureCount the sets of distinct primes between A and B, inclusive, whose sum equals K.	Medium5	Divide and conquerHash map+1	No attempts yet	1s	1024 MB	Judgeable
The Labyrinth with Changing ExitsFind the shortest time Hyungjin needs to start at vertex 1 and leave through an exit that is open when he reaches it, where exits open in turn every K seconds.	Medium5	GraphShortest path+1	No attempts yet	1s	1024 MB	Judgeable
Find the Root of the TreeGiven an unrooted tree and the fact that LCA(a, b) = x for the unknown root, count the vertices that could be that root.	Medium5	TreeDFS	No attempts yet	1s	1024 MB	Judgeable
Enchanted MazeFind the least number of seconds for twins who attempt the same direction each step to both reach the exits, with switches toggling obstacles.	Medium5	BFSSimulation+1	No attempts yet	3s	1024 MB	Judgeable
Guard EvadersGiven the initial facing of each guard and the number of players, decide whether every player can slip through a gap between two guards without being caught.	Medium5	Brute forceSimulation	No attempts yet	1s	1024 MB	Judgeable
Jigsaw PuzzleGiven jigsaw pieces labeled by notches, flats, and projections, decide whether they can form a rectangular puzzle under three progressively stricter criteria.	Medium5	MathCombinatorics+1	No attempts yet	1s	1024 MB	Judgeable
Clearing the TrackGiven a circular track where each pickup reverses direction, find the total distance Dalgu walks until all trash is removed.	Medium5	MathSimulation+1	No attempts yet	1s	1024 MB	Judgeable
Making a SequenceGiven N, construct a sequence of non-negative integers at most N so that exactly N contiguous intervals have sums divisible by N, or print -1 if impossible.	Medium5	Prefix sumMath+1	No attempts yet	1s	1024 MB	Judgeable
GradesGiven an N by N grid of scores, find the largest pocket money left after deleting one rectangular sub-table, where each score adds (score minus 50).	Medium5	MatrixDynamic programming+1	No attempts yet	1s	1024 MB	Judgeable