Problems

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Total results29,475 problems

Regular hexagon and triangles
Easy3
Geometry, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Diwali lightings
Easy3
Math, Prefix sum+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Diwali lightings (Large)
Easy3
Math, Prefix sum+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Beautiful Numbers (Small)
Easy3
Math, Brute force+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Vote (Small)
Easy3
Math, Probability+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Rank and File (Large)
Easy3
Implementation, Hash map+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Counting Sheep (Small)
Easy3
Simulation, Implementation+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Coin Jam (Small)
Easy3
Brute force, Math+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Pikachu
Easy3
String, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Baskin-Robbins 31
Easy3
Math, Implementation+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Don't Be Last!
Easy3
Hash map, Sorting
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hoof, Paper, Scissors (Bronze)
Easy3
Brute force, Simulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Why Did the Cow Cross the Road 5
Easy3
Sliding window, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Why Did the Cow Cross the Road 1
Easy3
Array, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Why Did the Cow Cross the Road 3
Easy3
Sorting, Simulation
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Election of Evil
Easy3
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The Lost Cow
Easy3
Math, Simulation
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
String Permutation
Easy3
Backtracking, Recursion+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Vote
Easy3
Hash map, Implementation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Squares in a grid square
Easy3
Math, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Prison Break
Easy3
Graph, BFS+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Palindrome in base n
Easy3
Math, Implementation+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Closest bus stops
Easy3
Sorting, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Building a timetable
Easy3
Bit manipulation, Brute force+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Addition and Multiplication
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Breaking Caesar's cipher
Easy3
String, Brute force+1
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Club Room Project (Small)
Easy3
Union-find, Implementation
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Salt and Pepper (Small)
Easy3
Array, Sorting+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Splitting the Pizza Tower (Small)
Easy3
Dynamic programming, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Riemann Sum Offset (Small)
Easy3
Math, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Kim's Diner
Easy3
Simulation, Sorting+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
What's Your Tier?
Easy3
Probability, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Calculate!
Easy3
Bit manipulation, Math+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
High-End Artwork
Easy3
Simulation, Array+1
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Mun, Hong, An
Easy3
Implementation, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Walking to Sincheon Station, Sam (Small)
Easy3
Math, Brute force+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Sickly Yeongjeong
Easy3
Hash map, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Hyobin's Tutoring
Easy3
Implementation, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Exactly Electrical
Easy3
Math, Implementation+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Sum Game
Easy3
Prefix sum, Array
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
High Tide, Low Tide
Easy3
Sorting, Greedy+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Vera and Trail Building
Easy3
Greedy, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Ttakji Game
Easy3
Implementation, Array+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Assigning rooms
Easy3
Dynamic programming, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Broken clock
Easy3
Math, Number theory+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Nemmo Nemmo (Easy)
Easy3
Brute force, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Banner
Easy3
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sat Down
Easy3
Brute force, Implementation+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Report Card
Easy3
Brute force, Math+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
The N-th Positive Rational Number
Easy3
Math, Implementation+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Cramming
Easy3
Dynamic programming, Array+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Polynomial Derivative (Large)
Easy3
Math, Number theory+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Coke Drinking Contest
Easy3
Math, Simulation+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Reverse Nonogram
Easy3
Implementation, Simulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Election
Easy3
Probability, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Password Hacking
Easy3
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Tracking Fake News
Easy3
Graph, BFS+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
County Fair Events
Easy3
Greedy, Sorting+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Oversized Pancake Flipper (Small)
Easy3
Greedy, Brute force+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Alphabet Cake (Large)
Easy3
Implementation, Simulation+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Younghoon the Informatics God
Easy3
Math, Implementation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Finding matching pairs
Easy3
Sorting, Brute force+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Digit frequency
Easy3
Math, Implementation
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Coin change
Easy3
Greedy, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Big Number
Easy3
String, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Easy Shortest Distance
Easy3
BFS, Graph+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Happy Number
Easy3
Simulation, Hash map+1
No attempts yet
Time limit
0.2s
Memory limit
512 MB
Judgeable
Cezar's Blackjack
Easy3
Implementation, Math+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Amusement Anticipation
Easy3
Implementation, Array
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Falling Apart
Easy3
Dynamic programming, Game theory+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Time is of the Essence
Easy3
Math, Implementation
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The Key to Cryptography
Easy3
String, Implementation
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Is Everybody Appy?
Easy3
Hash map, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
DRM Messages
Easy3
String, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Game of Throwns
Easy3
Stack, Simulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Odd Palindrome
Easy3
String, Brute force+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Unloaded Die
Easy3
Math, Greedy+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Star Arrangements
Easy3
Math, Brute force+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Law 11: Offside Position
Easy3
Implementation, Geometry+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Lights in the Morning
Easy3
Implementation, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Golf Croquet
Easy3
Simulation, Implementation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Fitness
Easy3
Simulation, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Musical Chairs
Easy3
Simulation, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
League Tables
Easy3
Implementation, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Another Brick in the Wall
Easy3
Simulation, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Number Pairs
Easy3
Array, Hash map+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Counting Domino Spots
Easy3
Math, Combinatorics
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cipher
Easy3
Sorting, Hash map+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Paint bucket
Easy3
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Knight minimum moves
Easy3
BFS, Graph+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Palindromic Password
Easy3
Array, Brute force+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Selling pills
Easy3
Math, Greedy+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Name Compatibility
Easy3
Implementation, Simulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Bank Card Verifier
Easy3
Implementation, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Aron's Place in Line
Easy3
Implementation, String+2
No attempts yet
Time limit
1s
Memory limit
32 MB
Judgeable
Olivander's wand boxes
Easy3
Sorting, Greedy+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Odd Gnome
Easy3
Array, Implementation
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Progressive Scramble
Easy3
Implementation, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Vera and ABCDE
Easy3
Implementation, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Blocked Billboard
Easy3
Geometry, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Regular hexagon and trianglesChoose three non-crossing diagonals of a regular hexagon to maximize the smallest of the four resulting triangles' areas, for side length L.	Easy3	GeometryGreedy+1	No attempts yet	2s	512 MB	Judgeable
Diwali lightingsGiven a pattern S repeated infinitely and a range [I, J], count how many bulbs in that range are blue.	Easy3	MathPrefix sum+2	No attempts yet	5s	512 MB	Judgeable
Diwali lightings (Large)Given a pattern string repeated forever, count how many blue bulbs appear between positions I and J in the infinite sequence.	Easy3	MathPrefix sum+2	No attempts yet	5s	512 MB	Judgeable
Beautiful Numbers (Small)For each N, find a base B > 1 where N is written with only the digit 1, preferring the base with the most 1 digits.	Easy3	MathBrute force+2	No attempts yet	5s	512 MB	Judgeable
Vote (Small)Given N supporters of A and M of B, find the probability that A leads after every vote in a random arrival order.	Easy3	MathProbability+1	No attempts yet	5s	512 MB	Judgeable
Rank and File (Large)Given all but one of the rows and columns of a sorted grid, find the missing list of heights in increasing order.	Easy3	ImplementationHash map+1	No attempts yet	5s	512 MB	Judgeable
Counting Sheep (Small)Track which digits 0 to 9 appear as Bleatrix counts multiples of N, and report the last multiple or INSOMNIA if digit 9 never completes.	Easy3	SimulationImplementation+1	No attempts yet	5s	512 MB	Judgeable
Coin Jam (Small)Print the J lexicographically smallest 0/1 strings of length N whose values in bases 2 through 10 are all composite, with the smallest prime factor for each base.	Easy3	Brute forceMath+2	No attempts yet	5s	512 MB	Judgeable
PikachuDecide whether a given lowercase string can be split into a sequence of the tokens "pi", "ka", and "chu".	Easy3	StringGreedy+1	No attempts yet	2s	512 MB	Judgeable
Baskin-Robbins 31Given n games with parameters j and m, compute how many turns each lasts and report the earliest game with the minimum turn count.	Easy3	MathImplementation+2	No attempts yet	2s	256 MB	Judgeable
Don't Be Last!Sum each of the seven cows' milk output, then report the cow with the second-smallest total, or Tie if none or several qualify.	Easy3	Hash mapSorting	No attempts yet	2s	512 MB	Judgeable
Hoof, Paper, Scissors (Bronze)Given a sequence of pairs of gesture numbers, try all six ways to map numbers 1,2,3 to hoof, paper, scissors and report the largest number of games the first cow wins under any mapping.	Easy3	Brute forceSimulation+1	No attempts yet	2s	512 MB	Judgeable
Why Did the Cow Cross the Road 5Given N traffic lights with B known broken positions, find the minimum number of broken lights to repair so that some K consecutive lights all work.	Easy3	Sliding windowArray+2	No attempts yet	2s	512 MB	Judgeable
Why Did the Cow Cross the Road 1Given observations of which side of the road each of 10 cows stands on, count how many times a cow changes sides between consecutive observations of that cow.	Easy3	ArrayImplementation+2	No attempts yet	2s	512 MB	Judgeable
Why Did the Cow Cross the Road 3Given each cow's arrival and inspection time, find the earliest time all cows finish entering when inspected one at a time in arrival order.	Easy3	SortingSimulation	No attempts yet	2s	512 MB	Judgeable
Election of EvilGiven directed persuasion edges and a set of already-controlled representatives, list the reachable members of target set V in alphabetical order.	Easy3	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
The Lost CowGiven start x and target y on a number line, simulate a doubling zig-zag search and report the total distance traveled until y is reached.	Easy3	MathSimulation	No attempts yet	2s	512 MB	Judgeable
String PermutationPrint every permutation of a short string of distinct characters, in the order given by the original character positions.	Easy3	BacktrackingRecursion+1	No attempts yet	5s	512 MB	Judgeable
VoteSum each candidate's results across vote centers and report the unique top scorer, or a dilemma if there is a tie.	Easy3	Hash mapImplementation+1	No attempts yet	2s	512 MB	Judgeable
Squares in a grid squareFor each grid side length l, count every square whose sides lie along grid lines, including tilted ones.	Easy3	MathCombinatorics+1	No attempts yet	2s	512 MB	Judgeable
Prison BreakGiven a grid of '+' and '*' huts where movement is allowed only between huts of the same symbol, decide whether the entry hut can reach the exit hut.	Easy3	GraphBFS+1	No attempts yet	2s	512 MB	Judgeable
Palindrome in base nFor each query, convert the decimal number A to base n and report whether its digit sequence reads the same forwards and backwards.	Easy3	MathImplementation+2	No attempts yet	1s	256 MB	Judgeable
Closest bus stopsGiven n distinct integer coordinates on a line, find the smallest absolute difference between any two and count how many pairs achieve it.	Easy3	SortingArray+1	No attempts yet	1s	128 MB	Judgeable
Building a timetableFor each student, count the courses whose every meeting period lies among that student's free periods.	Easy3	Bit manipulationBrute force+1	No attempts yet	1s	128 MB	Judgeable
Addition and MultiplicationFor integers a < b, multiply the triangular numbers T(k)=1+2+...+k for k from a to b, and print the result modulo 14579.	Easy3	MathImplementation	No attempts yet	1s	128 MB	Judgeable
Breaking Caesar's cipherTry all 26 Caesar shifts on the ciphertext and pick the one whose plaintext contains a dictionary word as a substring.	Easy3	StringBrute force+1	No attempts yet	1s	64 MB	Judgeable
Club Room Project (Small)Given N rooms in a row and M wall-breaking actions, count how many rooms remain after all actions merge neighboring rooms.	Easy3	Union-findImplementation	No attempts yet	1s	512 MB	Judgeable
Salt and Pepper (Small)Given an M by N brightness matrix and odd window size W, output the median of every W by W window.	Easy3	ArraySorting+1	No attempts yet	1s	512 MB	Judgeable
Splitting the Pizza Tower (Small)A tower of N pizzas is repeatedly split into two smaller towers, each split scoring the product of the two new heights. Find the maximum total score (N ≤ 10).	Easy3	Dynamic programmingMath+1	No attempts yet	1s	512 MB	Judgeable
Riemann Sum Offset (Small)For a linear polynomial, find the offset epsilon in [0, dx] that makes the Riemann sum equal the exact integral, or print -1.	Easy3	MathImplementation+2	No attempts yet	1s	512 MB	Judgeable
Kim's DinerMaintain a list of pending orders under append, sort by (time, table), and delete-by-table commands, printing the list after each query.	Easy3	SimulationSorting+2	No attempts yet	2s	256 MB	Judgeable
What's Your Tier?Starting at 2000 points, play 20 games with given win, loss, and draw probabilities; compute the probability of ending in each of five tiers.	Easy3	ProbabilityDynamic programming+2	No attempts yet	2s	256 MB	Judgeable
Calculate!Given A, B and a huge count C, find the value of A after XORing B into it C times.	Easy3	Bit manipulationMath+1	No attempts yet	1s	256 MB	Judgeable
High-End ArtworkStamps are pressed onto a paper in a given order; later presses overwrite earlier ones. Print the final grid, using '.' for untouched cells.	Easy3	SimulationArray+1	No attempts yet	4s	512 MB	Judgeable
Mun, Hong, AnEach secretary adds one step to every stone in one direction from the start. Count total steps per stone modulo 3, then split P by the final blue, red, and green counts.	Easy3	ImplementationPrefix sum+2	No attempts yet	2s	256 MB	Judgeable
Walking to Sincheon Station, Sam (Small)Count N-digit numbers using only digits 0, 1, 2 that are divisible by 3 and have no leading zero.	Easy3	MathBrute force+1	No attempts yet	2s	256 MB	Judgeable
Sickly YeongjeongMap each symptom to its medicine name, then for every query list output the matching medicines in order or YOU DIED if any symptom is untreatable.	Easy3	Hash mapImplementation+2	No attempts yet	1s	512 MB	Judgeable
Hyobin's TutoringMultiply N matrices in the given order and print the sum of the product's entries modulo 1,000,000,007, or -1 if the shapes do not line up.	Easy3	ImplementationMath+1	No attempts yet	1s	512 MB	Judgeable
Exactly ElectricalGiven start and destination grid points and a battery charge t, decide whether a walk of exactly t unit steps connects them.	Easy3	MathImplementation+1	No attempts yet	1s	512 MB	Judgeable
Sum GameGiven two length-N sequences of daily scores, find the largest K where the prefix sums of both sequences are equal.	Easy3	Prefix sumArray	No attempts yet	1s	512 MB	Judgeable
High Tide, Low TideGiven N distinct measurements taken alternately low, high, low, high..., with rising highs and falling lows, reconstruct the original order.	Easy3	SortingGreedy+1	No attempts yet	1s	512 MB	Judgeable
Vera and Trail BuildingGiven K, follow a fixed greedy decomposition into complete blocks and print the resulting connected trail network with exactly K two-edge-disjoint paths.	Easy3	GreedyGraph+2	No attempts yet	1s	512 MB	Judgeable
Ttakji GameFor each of N rounds, compare two cards by counting stars, then circles, then squares, then triangles, and print which player wins or a draw.	Easy3	ImplementationArray+1	No attempts yet	2s	512 MB	Judgeable
Assigning roomsGiven three distinct room capacities and a student count, decide whether some nonnegative combination of the capacities sums exactly to the count.	Easy3	Dynamic programmingMath+2	No attempts yet	2s	512 MB	Judgeable
Broken clockGiven the clock-face angles of an hour hand and a minute hand in whole degrees, decide whether both can point that way at the same instant on a working clock.	Easy3	MathNumber theory+2	No attempts yet	0.5s	512 MB	Judgeable
Nemmo Nemmo (Easy)Count subsets of cells of an N by M grid, with N*M at most 25, that contain no full 2 by 2 square of chosen cells.	Easy3	Brute forceBit manipulation+2	No attempts yet	1s	512 MB	Judgeable
BannerCount connected groups of 1s in an M by N grid where cells touching in any of the eight directions belong to the same group.	Easy3	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
Sat DownGiven your two cards, count how many of the 18 choose 2 possible opponent hands you beat, and print the win probability to three decimals.	Easy3	Brute forceImplementation+2	No attempts yet	1s	256 MB	Judgeable
Report CardGiven N (x, y) points, find positive integers a and b up to 100 that minimize the sum of squared residuals of f(x) = ax + b.	Easy3	Brute forceMath+1	No attempts yet	1s	256 MB	Judgeable
The N-th Positive Rational NumberGiven N, return the N-th term of the diagonal enumeration of positive rationals where each group of constant numerator plus denominator is listed with decreasing numerator.	Easy3	MathImplementation+1	No attempts yet	1s	256 MB	Judgeable
CrammingGiven N chapters, each with a study time and a score, choose a subset whose total study time fits in T to maximize the total score.	Easy3	Dynamic programmingArray+2	No attempts yet	2s	256 MB	Judgeable
Polynomial Derivative (Large)Given a polynomial as coefficient-exponent pairs, compute the value of its derivative at x = 2 modulo 1e9+7.	Easy3	MathNumber theory+1	No attempts yet	3s	256 MB	Judgeable
Coke Drinking ContestGiven N entrants who each drink A mL per second with fixed drinking and resting periods, find when the first entrant finishes K mL.	Easy3	MathSimulation+1	No attempts yet	1s	512 MB	Judgeable
Reverse NonogramGiven a solved nonogram grid of '.' and 'X', print the run-length clues for every row and then every column.	Easy3	ImplementationSimulation+2	No attempts yet	2s	512 MB	Judgeable
ElectionGiven N total votes, M counted votes split as V1 and V2, and a threshold W, decide if the probability that candidate 1 wins (when each remaining vote is a fair coin) exceeds W%.	Easy3	ProbabilityMath+2	No attempts yet	1s	512 MB	Judgeable
Password HackingGiven each password's probability of being correct, find the expected number of attempts when trying passwords in the order that minimizes it.	Easy3	GreedySorting+2	No attempts yet	1s	512 MB	Judgeable
Tracking Fake NewsModel a story spreading through a social network where each person reposts only if a weighted sum of the story's categories equals their target.	Easy3	GraphBFS+1	No attempts yet	2s	512 MB	Judgeable
County Fair EventsGiven N intervals, find the maximum number of non-overlapping intervals John can attend.	Easy3	GreedySorting+1	No attempts yet	2s	512 MB	Judgeable
Oversized Pancake Flipper (Small)Given a row of pancakes and a flipper of fixed length K, find the minimum number of flips to make all pancakes happy, or report impossibility.	Easy3	GreedyBrute force+1	No attempts yet	5s	512 MB	Judgeable
Alphabet Cake (Large)Fill every blank cell in a grid so each distinct letter occupies one axis-aligned rectangle, following the prescribed row-by-row expansion rule.	Easy3	ImplementationSimulation+1	No attempts yet	5s	512 MB	Judgeable
Younghoon the Informatics GodCompute Younghoon's total score from N solved problems, then compare it against P scores to decide whether his rank is within the top 15%.	Easy3	MathImplementation+1	No attempts yet	2s	512 MB	Judgeable
Finding matching pairsGiven 2 to 10 integers and a target, print every position pair that sums to the target in lexicographic order, then the count.	Easy3	SortingBrute force+1	No attempts yet	2s	512 MB	Judgeable
Digit frequencyCount how many times a given digit d appears when writing every integer from 1 to n.	Easy3	MathImplementation	No attempts yet	2s	512 MB	Judgeable
Coin changeFind the fewest 2 won and 5 won coins that sum to n, or report -1 when no combination works.	Easy3	GreedyMath+1	No attempts yet	2s	512 MB	Judgeable
Big NumberGiven a non-negative integer with up to a million digits, print its remainder modulo 20000303.	Easy3	StringMath+2	No attempts yet	2s	512 MB	Judgeable
Easy Shortest DistanceGiven a grid with one target cell and blocked cells, find the shortest distance from each open cell to the target using 4-directional moves.	Easy3	BFSGraph+1	No attempts yet	1s	128 MB	Judgeable
Happy NumberDecide whether repeatedly summing the squares of a number's decimal digits ever reaches 1.	Easy3	SimulationHash map+1	No attempts yet	0.2s	512 MB	Judgeable
Cezar's BlackjackGiven the values of N drawn cards summing to at most 21, decide whether to draw again based on how many remaining cards exceed the gap to 21.	Easy3	ImplementationMath+2	No attempts yet	1s	64 MB	Judgeable
Amusement AnticipationFor each sequence, find the starting position of the longest contiguous arithmetic run that ends at the last element.	Easy3	ImplementationArray	No attempts yet	2s	512 MB	Judgeable
Falling ApartGiven up to 15 positive integers, two players alternately take one piece; find the final sums under optimal play.	Easy3	Dynamic programmingGame theory+1	No attempts yet	2s	512 MB	Judgeable
Time is of the EssenceGiven a chain of unit conversions and an amount in the smallest unit, print a rounded answer in the largest unit and a rough answer in the top two units.	Easy3	MathImplementation	No attempts yet	2s	512 MB	Judgeable
The Key to CryptographyGiven an autokey cipher's ciphertext and secret word, recover the original plaintext message.	Easy3	StringImplementation	No attempts yet	2s	512 MB	Judgeable
Is Everybody Appy?Given each kid's ranked list of apps from oldest to youngest, assign each kid the highest-ranked app not already taken by an older kid.	Easy3	Hash mapGreedy+2	No attempts yet	2s	512 MB	Judgeable
DRM MessagesSplit a string in half, rotate each half by its character sum, then merge the halves by rotating one half with the other's values.	Easy3	StringImplementation+2	No attempts yet	2s	512 MB	Judgeable
Game of ThrownsTrack a token around a circle of children through clockwise or counterclockwise throws, undoing the last m throws on command.	Easy3	StackSimulation+1	No attempts yet	2s	512 MB	Judgeable
Odd PalindromeGiven a lowercase string, decide whether every palindromic substring has odd length, printing Odd. or Or not.	Easy3	StringBrute force+1	No attempts yet	1s	512 MB	Judgeable
Unloaded DieGiven probabilities of the six faces of a loaded die, change one face's label so the expected value is exactly 3.5, minimizing the absolute label change.	Easy3	MathGreedy+1	No attempts yet	1s	512 MB	Judgeable
Star ArrangementsGiven S stars, list every appealing row pattern a,b where alternating rows of a and b stars use exactly S stars.	Easy3	MathBrute force+1	No attempts yet	1s	512 MB	Judgeable
Law 11: Offside PositionGiven the ball's position and 11 attackers plus 11 defenders, decide whether any attacker is in an offside position per two coordinate conditions.	Easy3	ImplementationGeometry+2	No attempts yet	2s	512 MB	Judgeable
Lights in the MorningGiven each light's first green time and green/red cycle, decide whether a car driving 1 km per minute reaches every light during green.	Easy3	ImplementationMath+1	No attempts yet	2s	512 MB	Judgeable
Golf CroquetSimulate a golf croquet doubles game from a stroke record and report the score and standing once a team reaches 7 points.	Easy3	SimulationImplementation+1	No attempts yet	2s	512 MB	Judgeable
FitnessSimulate moves around 8 circularly numbered stations and print the visited sequence, marking it reject if fewer than 5 distinct stations appear or any station repeats.	Easy3	SimulationImplementation+2	No attempts yet	2s	512 MB	Judgeable
Musical ChairsSimulate musical chairs: each round every remaining player shifts M seats clockwise, the player at seat S is eliminated, and seats are renumbered until R rounds pass.	Easy3	SimulationImplementation+2	No attempts yet	2s	512 MB	Judgeable
League TablesGiven each team's current record and a list of match results, update the records and print the table sorted by points, goal difference, goals scored, then name.	Easy3	ImplementationSorting+2	No attempts yet	2s	512 MB	Judgeable
Another Brick in the WallSimulate laying bricks in pile order across h layers of width w, and report whether every layer fills exactly before the pile runs out.	Easy3	SimulationImplementation+2	No attempts yet	2s	512 MB	Judgeable
Number PairsCount pairs of distinct values in a sequence that sum to a target K, where order does not matter and each element is used once.	Easy3	ArrayHash map+2	No attempts yet	2s	512 MB	Judgeable
Counting Domino SpotsCompute the total number of spots over all distinct unordered pairs of mark values from 0 to N.	Easy3	MathCombinatorics	No attempts yet	2s	512 MB	Judgeable
CipherSort a sequence of N integers by decreasing frequency, breaking ties by the order each value first appears in the input.	Easy3	SortingHash map+1	No attempts yet	2s	512 MB	Judgeable
Paint bucketFlood fill a grid from one pixel, repainting all side-connected pixels sharing the clicked color with a new color, then print the grid.	Easy3	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
Knight minimum movesGiven two squares on an 8x8 chessboard, output the fewest knight moves needed to get from the first to the second.	Easy3	BFSGraph+1	No attempts yet	2s	512 MB	Judgeable
Palindromic PasswordFor each six-digit number, print the closest six-digit palindrome, breaking ties by choosing the smaller one.	Easy3	ArrayBrute force+1	No attempts yet	3s	512 MB	Judgeable
Selling pillsGiven N, build the fixed canonical pouch layout of (b-1) ones followed by c copies of b, where b^2 >= N and c = ceil(N/b).	Easy3	MathGreedy+1	No attempts yet	1s	512 MB	Judgeable
Name CompatibilityInterleave two equal-length names letter by letter, replace each letter with its stroke count, then repeatedly sum adjacent digits (keeping the ones digit) until two remain.	Easy3	ImplementationSimulation+2	No attempts yet	1s	512 MB	Judgeable
Bank Card VerifierEach test case gives a 16-digit card number as four 4-digit groups; apply the Luhn checksum rule and print Yes if the total is a multiple of 10, otherwise No.	Easy3	ImplementationString+2	No attempts yet	2s	512 MB	Judgeable
Aron's Place in LineGiven the shirt colors of people in line, where each maximal run of equal colors is one group, find the position Aron occupies at the back.	Easy3	ImplementationString+2	No attempts yet	1s	32 MB	Judgeable
Olivander's wand boxesGiven N wand lengths and N box sizes, decide whether every wand can be paired with a distinct box whose size is at least the wand length.	Easy3	SortingGreedy+2	No attempts yet	1s	64 MB	Judgeable
Odd GnomeFor each group of unique IDs whose non-king elements increase by exactly one, output the 1-based position of the single out-of-order gnome.	Easy3	ArrayImplementation	No attempts yet	2s	512 MB	Judgeable
Progressive ScrambleEncrypt a message by cumulative sums of symbol values mod 27, and decrypt by inverting the same recurrence.	Easy3	ImplementationMath+2	No attempts yet	2s	512 MB	Judgeable
Vera and ABCDEGiven a string of N letters from A to E, render the 5x3 pattern for each letter side by side and print the resulting 5 rows of 3N characters.	Easy3	ImplementationString+2	No attempts yet	2s	512 MB	Judgeable
Blocked BillboardGiven two non-overlapping billboards and one truck rectangle, compute the total billboard area not covered by the truck.	Easy3	GeometryImplementation+2	No attempts yet	2s	512 MB	Judgeable