Problems

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Total results29,473 problems

Precious Stones
Easy3
Array, Hash map+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
School List
Easy3
Hash map, String+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Air Conditioners
Easy3
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Casting
Easy3
Math, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Herons
Easy3
Math, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Checkers
Easy3
Greedy, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
A Freshman Needs Friends
Easy3
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Pascal's Triangle
Easy3
Math, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Eraser
Easy3
Simulation, Array+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Gahee, Are You Sleeping There?
Easy3
Implementation, Geometry+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Getting Started with Calculus
Easy3
Math, Implementation+1
No attempts yet
Time limit
0.5s
Memory limit
1024 MB
Judgeable
Innohorse
Easy3
Implementation, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
The Game
Easy3
Greedy, Implementation+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Light Bulbs
Easy3
Array, Simulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Coprime Average
Easy3
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Blog
Easy3
Sliding window, Array+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Standing Tall on the Lofty Namsan
Easy3
Array, Implementation+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Light-Cycle Race
Easy3
Simulation, Implementation
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Illumination 2
Easy3
Prefix sum, Greedy+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Buying a Bicycle
Easy3
Math, Greedy+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Digital Roots
Easy3
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Magic Cards
Easy3
Sorting, Greedy+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Opinion Poll
Easy3
Math, Implementation+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Triangles
Easy3
Brute force, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Origami
Easy3
Math, Implementation+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Changyeong and Coffee
Easy3
Dynamic programming, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Chocolate Bar
Easy3
Implementation, Greedy+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Game
Easy3
Game theory, Math+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Parallelepiped
Easy3
Sorting, Greedy+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Universal Socket
Easy3
Geometry, Hash map+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Border
Easy3
Array, Implementation+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Dessert Preparation
Easy3
Brute force, Implementation+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Map
Easy3
Implementation, String+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Cataloguing numbers
Easy3
Implementation, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Chairs
Easy3
Sorting, Intervals+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Non-Integer Donuts
Easy3
Implementation, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
squarePrime
Easy3
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Rectangle Area
Easy3
Simulation, Implementation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Hey Kakao
Easy3
Probability, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
nm Grid Multiplication
Easy3
Implementation, Brute force+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Era Name Change
Easy3
Implementation, Math
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
A-Un Breathing
Easy3
Greedy, Implementation
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Koto Municipal Subway
Easy3
Math, Brute force+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Step Aerobics
Easy3
Simulation, Implementation
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Testing Logical Equation Identities
Easy3
String, Brute force+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Kagisys
Easy3
Hash map, Simulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
QWERTY Hand Switch Count
Easy3
Implementation, String+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Moonlight Farm
Easy3
Sorting, Implementation+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Luck Manipulator
Easy3
Simulation, Implementation+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Galaxy Wide Web Service
Easy3
Array, Simulation+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Princess' Gamble
Easy3
Math, Implementation+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Mysterious Gems
Easy3
Simulation, Implementation+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Keitai Message
Easy3
Implementation, String+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Prime Digital Roots
Easy3
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Image is Everything
Easy3
Implementation, Array
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
When Can We Meet?
Easy3
Array, Implementation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Exploring Caves
Easy3
Simulation, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Fermat's Last Theorem
Easy3
Brute force, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Die Game
Easy3
Simulation, Implementation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Reversort
Easy3
Simulation, Implementation+2
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Binary Strawberry
Easy3
Math, Implementation+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Twinkle Twinkle 2
Easy3
Probability, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
K-Goodness String
Easy3
String, Greedy+2
No attempts yet
Time limit
Not set
Memory limit
1024 MB
Judgeable
Increasing Substring
Easy3
String, Dynamic programming+1
No attempts yet
Time limit
Not set
Memory limit
1024 MB
Judgeable
Arithmetic Square
Easy3
Implementation, Brute force+2
No attempts yet
Time limit
Not set
Memory limit
1024 MB
Judgeable
Packing Items
Easy3
Simulation, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Participant List
Easy3
Implementation, Sorting
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Scytale Cipher
Easy3
Implementation, String+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Heliocentric
Easy3
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
In or Out
Easy3
Simulation, Math+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Counting Stars
Easy3
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Unique Shapes
Easy3
Brute force, Backtracking+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Sport Climbing Combined
Easy3
Sorting, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Periodical Cicadas
Easy3
Math, Number theory+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Movie Rating
Easy3
Sorting, Array+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Olympic Ranking
Easy3
Sorting, Implementation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Aliquot Sum
Easy3
Math, Number theory+2
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Gets and Puts (Easy)
Easy3
Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Histogram
Easy3
Array, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Ljeto
Easy3
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Kick Start
Easy3
Implementation, Sorting+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
IQ
Easy3
Sorting, Greedy+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Quadratic equation
Easy3
Math, Implementation+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Deja vu of Go Players
Easy3
Game theory, Implementation
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Transform the String
Easy3
String, Brute force+2
No attempts yet
Time limit
Not set
Memory limit
1024 MB
Judgeable
Wards
Easy3
BFS, Simulation+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Turning Knobs
Easy3
Implementation, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Drawing a Snail - ㅂ
Easy3
Implementation, Simulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Drawing Snail - Rotated ㅈ
Easy3
Implementation, Simulation
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Rotation
Easy3
Math, Simulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
WiFi
Easy3
Implementation, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Sequence (Easy)
Easy3
Math, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Decalcomania
Easy3
Implementation, Array+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Algorithm Class - Selection Sort 1
Easy3
Sorting, Simulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Alpsoo
Easy3
Implementation, String+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Allocation
Easy3
Greedy, Sorting
No attempts yet
Time limit
15s
Memory limit
1024 MB
Judgeable
Countdown
Easy3
Array, Sliding window+1
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Record Breaker
Easy3
Array, Implementation+1
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Longest Arithmetic
Easy3
Array, Implementation+1
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Maximum Coins
Easy3
Array, Prefix sum+2
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Precious StonesCount pairs of indices i < j in a string whose letters form one of k given ordered pairs.	Easy3	ArrayHash map+1	No attempts yet	2s	1024 MB	Judgeable
School ListCount registrations per school number parsed from each name, then list the numbers of schools with between one and five participants.	Easy3	Hash mapString+1	No attempts yet	2s	1024 MB	Judgeable
Air ConditionersGiven n classrooms with minimum power requirements and m air conditioner models with power and price, find the minimum total cost to equip every classroom.	Easy3	GreedySorting+2	No attempts yet	2s	1024 MB	Judgeable
CastingGiven counts of tall, blue-eyed, and blond actors, find the minimum or maximum possible number who are all three.	Easy3	MathCombinatorics+1	No attempts yet	2s	1024 MB	Judgeable
HeronsEach heron shows one or two legs, and counts a and b come from two moments. Find the minimum and maximum possible total number of herons.	Easy3	MathGreedy+1	No attempts yet	2s	1024 MB	Judgeable
CheckersGiven a white pieces and b black pieces, arrange them in a tower to maximize the number of black stripes, where a stripe is a maximal run of adjacent black pieces.	Easy3	GreedyMath+2	No attempts yet	1s	512 MB	Judgeable
A Freshman Needs FriendsGiven an N by M grid with walls, Doyeon's start cell, and people, count how many people are reachable from her by moving up, down, left, or right.	Easy3	BFSGraph+2	No attempts yet	1s	1024 MB	Judgeable
Pascal's TriangleCount how many entries in row n of Pascal's triangle are odd, where n can be as large as 2 billion.	Easy3	MathBit manipulation+2	No attempts yet	2s	1024 MB	Judgeable
EraserStarting with 1..N in cells, repeatedly delete numbers in odd positions and shift left until one number remains; report that survivor.	Easy3	SimulationArray+2	No attempts yet	1s	512 MB	Judgeable
Gahee, Are You Sleeping There?Given a grid with one Gahee rectangle and one pillow rectangle, decide whether the two rectangles overlap, counting hidden pillow parts as overlap.	Easy3	ImplementationGeometry+2	No attempts yet	1s	512 MB	Judgeable
Getting Started with CalculusGiven epsilon as a fraction and a linear polynomial f, compute the limit L at x0 and the largest delta with \|f(x)-L\|<epsilon, printing delta as a fraction or 0 0.	Easy3	MathImplementation+1	No attempts yet	0.5s	1024 MB	Judgeable
InnohorseGiven the start and end cells of a knight-like jump on an 8x8 board, recover the ordered pair (x, y) with x <= y that describes the move.	Easy3	ImplementationMath+2	No attempts yet	1s	512 MB	Judgeable
The GameGiven a final score x:y where one team reached k points, reconstruct any valid sequence of scores after each question.	Easy3	GreedyImplementation+1	No attempts yet	1s	512 MB	Judgeable
Light BulbsApply M range or point updates to a binary array, where ranges can be flipped, set to 0, or set to 1, then print the final array.	Easy3	ArraySimulation+2	No attempts yet	1s	512 MB	Judgeable
Coprime AverageGiven a sequence and a number X, find the average of all elements that are coprime with X, within an error of 1e-6.	Easy3	MathNumber theory+2	No attempts yet	1s	512 MB	Judgeable
BlogGiven N daily visitor counts and a window size X, find the maximum sum over any X consecutive days and count how many windows reach it, printing SAD if the maximum is 0.	Easy3	Sliding windowArray+1	No attempts yet	1s	512 MB	Judgeable
Standing Tall on the Lofty NamsanGiven a sequence, decide whether it strictly increases to some peak position and strictly decreases afterward, printing YES or NO.	Easy3	ArrayImplementation+1	No attempts yet	1s	512 MB	Judgeable
Light-Cycle RaceSimulate two light cycles on a grid, moving one square per second along turn-and-distance paths, and report the finish time, positions, and alive or dead status at the first death or path end.	Easy3	SimulationImplementation	No attempts yet	1s	512 MB	Judgeable
Illumination 2You may turn on a prefix of the bulbs once, then flip individual bulbs; find the minimum number of flips to reach the target pattern.	Easy3	Prefix sumGreedy+2	No attempts yet	2s	1024 MB	Judgeable
Buying a BicycleGiven a one-ruble coins, b two-ruble coins, and a price c, decide whether some subset of the coins sums to exactly c.	Easy3	MathGreedy+1	No attempts yet	2s	256 MB	Judgeable
Digital RootsFor each range [a, b], count how often each digital root (1 to 9) appears and report the ones that appear most often.	Easy3	MathNumber theory+2	No attempts yet	1s	512 MB	Judgeable
Magic CardsGiven two n-card hands and a pick size l, decide whether Grisha's best l-card sum always beats Dima's worst l-card sum.	Easy3	SortingGreedy+2	No attempts yet	2s	256 MB	Judgeable
Opinion PollGiven n people, a who can solve the problem and b who refuse, find the minimum and maximum number who both can solve it and do not refuse.	Easy3	MathImplementation+1	No attempts yet	2s	256 MB	Judgeable
TrianglesFor each of T test cases with four segment lengths, count how many triples form a right, acute, or obtuse non-degenerate triangle.	Easy3	Brute forceMath+2	No attempts yet	1s	512 MB	Judgeable
OrigamiGiven an a by b grid, decide whether repeated full-length cuts that discard one piece can leave a rectangle of exactly S cells.	Easy3	MathImplementation+2	No attempts yet	2s	256 MB	Judgeable
Changyeong and CoffeeGiven N coffee cups with caffeine amounts, find the minimum number of cups whose contents sum to exactly K, or -1 if impossible.	Easy3	Dynamic programmingArray+2	No attempts yet	2s	512 MB	Judgeable
Chocolate BarFor each query, decide whether the left and right halves of a broken n by n bar can slide together to form the whole bar without overlapping.	Easy3	ImplementationGreedy+1	No attempts yet	2s	256 MB	Judgeable
GameIf the start is within Manhattan distance m of the finish, First wins on move 1; otherwise both players can avoid losing forever, so the result is Infinity.	Easy3	Game theoryMath+1	No attempts yet	2s	256 MB	Judgeable
ParallelepipedFor each set of twelve match lengths, decide whether they can form the edges of a rectangular parallelepiped frame, where four equal edges run along each of the three dimensions.	Easy3	SortingGreedy+1	No attempts yet	2s	256 MB	Judgeable
Universal SocketGiven n labeled points (phase or neutral), decide whether two points of opposite labels sit exactly distance d apart.	Easy3	GeometryHash map+2	No attempts yet	2s	256 MB	Judgeable
BorderGiven a grid of cells labeled A or B, count the unit edges that separate an A cell from a B cell.	Easy3	ArrayImplementation+2	No attempts yet	2s	256 MB	Judgeable
Dessert PreparationCount triples (dough, filling, ice cream) where none of the three ingredient pairs appears in the given lists of incompatible pairs.	Easy3	Brute forceImplementation+2	No attempts yet	2s	256 MB	Judgeable
MapParse a string of letters n, s, e, w each followed by 1-2 digit step counts, ignoring other characters, and report the distance from the red square to the final square.	Easy3	ImplementationString+2	No attempts yet	1s	512 MB	Judgeable
Cataloguing numbersFor each of three 9-digit cataloguing numbers, check that the encoded date is valid, the author digit is 1, 6, or 9, and the last digit equals the sum of squares of the first eight digits modulo 7.	Easy3	ImplementationMath+2	No attempts yet	1s	512 MB	Judgeable
ChairsGiven each person's entry and exit time on a single day, find the maximum number of people inside the library at any moment, counting entry and exit seconds as inside.	Easy3	SortingIntervals+2	No attempts yet	1s	512 MB	Judgeable
Non-Integer DonutsGiven an initial balance and N daily deposits, count the days on which the running balance is not a whole dollar amount.	Easy3	ImplementationMath+1	No attempts yet	1s	1024 MB	Judgeable
squarePrimeGiven a list of integers, return the sum of the values whose indices are prime numbers.	Easy3	MathNumber theory+2	No attempts yet	1s	512 MB	Judgeable
Rectangle AreaMaintain the current sheet height and width, and for each interior point cut in the direction that keeps the larger area, breaking ties by cutting horizontally.	Easy3	SimulationImplementation+1	No attempts yet	1s	1024 MB	Judgeable
Hey KakaoGiven win probability d% rising by k% after each loss, find the expected time in minutes until Iha wins a round of word chain.	Easy3	ProbabilityMath+2	No attempts yet	1s	1024 MB	Judgeable
nm Grid MultiplicationGiven sequences a and b, count how many times each digit 0-9 appears when writing every product a[i]*b[j] in decimal over the grid.	Easy3	ImplementationBrute force+1	No attempts yet	8s	512 MB	Judgeable
Era Name ChangeGiven a stored date as Heisei year, month, and day, decide whether it falls in Heisei or the new era starting May 1, 2019, and print the correct era name with the date.	Easy3	ImplementationMath	No attempts yet	8s	512 MB	Judgeable
A-Un BreathingGiven a sequence of A (Maeda speaks) and Un (Goto replies), decide whether each A can be matched to a later Un, with the conversation ending after all replies.	Easy3	GreedyImplementation	No attempts yet	10s	512 MB	Judgeable
Koto Municipal SubwayGiven D and E, find the integer point (x, y) with x + y = D that minimizes \|sqrt(x^2 + y^2) - E\| and print that minimum difference.	Easy3	MathBrute force+1	No attempts yet	8s	512 MB	Judgeable
Step AerobicsGiven a sequence of single-foot movements, count how many times both feet complete a full transition between floor and platform.	Easy3	SimulationImplementation	No attempts yet	8s	512 MB	Judgeable
Testing Logical Equation IdentitiesParse two logical formulas and decide whether they take the same truth value for every assignment of the variables a through k.	Easy3	StringBrute force+2	No attempts yet	8s	512 MB	Judgeable
KagisysSimulate a door lock: for each scanned card ID, print whether it opens, closes, or is unknown, toggling the door state on known IDs.	Easy3	Hash mapSimulation+2	No attempts yet	2s	512 MB	Judgeable
QWERTY Hand Switch CountFor each lowercase string until a terminating '#', count how many times the typing hand switches between consecutive characters on the standard QWERTY layout.	Easy3	ImplementationString+1	No attempts yet	8s	512 MB	Judgeable
Moonlight FarmFor each crop dataset, compute income per unit time from seed cost, growth stages, fruit yield, and harvest count, then list names by descending efficiency with ties broken alphabetically.	Easy3	SortingImplementation+2	No attempts yet	8s	512 MB	Judgeable
Luck ManipulatorSimulate an LCG frame by frame, advancing a reel whenever the random number matches its target, and report the frame when all N reels stop or -1 after 10000 frames.	Easy3	SimulationImplementation+1	No attempts yet	8s	512 MB	Judgeable
Galaxy Wide Web ServiceGiven each planet's daily access cycle and current hour, compute the maximum total access across all planets in any single absolute hour.	Easy3	ArraySimulation+2	No attempts yet	8s	512 MB	Judgeable
Princess' GambleGiven ticket counts per competitor, a winning competitor, and a deduction percentage, compute the payout per winning ticket, or 0 if no winning tickets exist.	Easy3	MathImplementation+1	No attempts yet	8s	512 MB	Judgeable
Mysterious GemsSimulate a robot starting at (10,10) that walks axis-aligned segments and check whether every given gem lies on some segment or its endpoint.	Easy3	SimulationImplementation+1	No attempts yet	8s	512 MB	Judgeable
Keitai MessageGiven a sequence of key presses, decode it by grouping repeated digits and mapping each group to a character via the phone keypad.	Easy3	ImplementationString+2	No attempts yet	8s	512 MB	Judgeable
Prime Digital RootsFor each number until 0, repeatedly sum its digits and stop early if a prime appears, then print the original and the prime digital root or none.	Easy3	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Image is EverythingGiven the six colored views of an N x N x N cube lattice, find the maximum number of cubes that can exist without contradicting any view.	Easy3	ImplementationArray	No attempts yet	2s	512 MB	Judgeable
When Can We Meet?Each member lists convenient days; pick the earliest day chosen by the most members, or 0 if no day reaches the quorum.	Easy3	ArrayImplementation+1	No attempts yet	2s	512 MB	Judgeable
Exploring CavesEach cave's path is given as successive displacement vectors; reconstruct the room coordinates and report the point farthest from the origin, breaking ties by largest x.	Easy3	SimulationImplementation+2	No attempts yet	2s	512 MB	Judgeable
Fermat's Last TheoremFor each z, find the largest sum of two positive cubes not exceeding z^3, then print z^3 minus that sum.	Easy3	Brute forceMath+2	No attempts yet	2s	512 MB	Judgeable
Die GameSimulate rolling a die on a table from a fixed starting orientation and report the number on the top face after each command sequence.	Easy3	SimulationImplementation+1	No attempts yet	2s	512 MB	Judgeable
ReversortSimulate the Reversort algorithm on a list of distinct integers and report the total cost, where each iteration costs the length of the reversed sublist.	Easy3	SimulationImplementation+2	No attempts yet	10s	1024 MB	Judgeable
Binary StrawberryGiven a turn number N, output the 4-beat binary strawberry chant, where each beat is V or strawberry according to the bouncing count from 1 to 15.	Easy3	MathImplementation+2	No attempts yet	0.5s	512 MB	Judgeable
Twinkle Twinkle 2Each light has an on-probability; an added light between neighbors turns on exactly when one neighbor is on. Find the expected total number of lit lights.	Easy3	ProbabilityMath+2	No attempts yet	1s	1024 MB	Judgeable
K-Goodness StringGiven a string, find the minimum number of character changes needed so exactly K mirrored position pairs differ.	Easy3	StringGreedy+2	No attempts yet	Not set	1024 MB	Judgeable
Increasing SubstringFor each position in a string, report the length of the longest strictly increasing substring ending there.	Easy3	StringDynamic programming+1	No attempts yet	Not set	1024 MB	Judgeable
Arithmetic SquareGiven a 3x3 grid with the center missing, choose any integer for the center to maximize how many of the 8 lines (3 rows, 3 columns, 2 diagonals) form arithmetic progressions.	Easy3	ImplementationBrute force+2	No attempts yet	Not set	1024 MB	Judgeable
Packing ItemsGiven R identical trucks each carrying the same n items in order, count how many length-B boxes are needed to pack all items greedily in sequence.	Easy3	SimulationMath+1	No attempts yet	1s	512 MB	Judgeable
Participant ListKeep the first M applicants per class, then print Blue (odd) classes before White (even), each class sorted by name length, then alphabetically.	Easy3	ImplementationSorting	No attempts yet	1s	512 MB	Judgeable
Scytale CipherGiven a ciphertext and rod diameter K, reconstruct the plaintext by reading the string in column-major order of K rows.	Easy3	ImplementationString+2	No attempts yet	1s	1024 MB	Judgeable
HeliocentricGiven the current day of Earth's 365-day orbit and Mars's 687-day orbit, find the smallest number of days until both planets are at day 0.	Easy3	MathNumber theory+2	No attempts yet	1s	1024 MB	Judgeable
In or OutFor each complex number c, iterate z = z^2 + c up to r times and report IN if \|z\| never exceeds 2, otherwise OUT.	Easy3	SimulationMath+1	No attempts yet	2s	1024 MB	Judgeable
Counting StarsCount the connected components of white pixels in a black-and-white bitmap, where adjacency is vertical or horizontal.	Easy3	GraphDFS+2	No attempts yet	2s	1024 MB	Judgeable
Unique ShapesCount the number of distinct polyominoes (free polyominoes) that can be formed from exactly 8 unit squares, where shapes matching under rotation, translation, or reflection count as one.	Easy3	Brute forceBacktracking+2	No attempts yet	2s	1024 MB	Judgeable
Sport Climbing CombinedGiven each athlete's ranks in three climbing events, sort them by the product of ranks, then by rank sum, then by bib number, and print the top three bib numbers.	Easy3	SortingImplementation+2	No attempts yet	1s	1024 MB	Judgeable
Periodical CicadasFor each pair of cicadas with cycles c1 and c2 last seen together in year y, find the earliest year any pair reappears together, which is y plus lcm(c1, c2).	Easy3	MathNumber theory+1	No attempts yet	1s	1024 MB	Judgeable
Movie RatingGiven N ratings, remove the L lowest and H highest scores and print the average of the rest.	Easy3	SortingArray+1	No attempts yet	1s	1024 MB	Judgeable
Olympic RankingEach line gives a country's gold, silver, and bronze medal counts; print the country that ranks first by the lexicographic order on (gold, silver, bronze).	Easy3	SortingImplementation+1	No attempts yet	1s	1024 MB	Judgeable
Aliquot SumFor each of up to a million numbers, sum its proper divisors and report whether it is abundant, deficient, or perfect.	Easy3	MathNumber theory+2	No attempts yet	8s	1024 MB	Judgeable
Gets and Puts (Easy)The statement gives only an execution step limit and no task description, so no algorithmic problem can be identified.	Easy3	Implementation	No attempts yet	1s	1024 MB	Judgeable
HistogramGiven bin size, bin count, and data points, count how many points fall in each bin and print a histogram with # bars on a - base.	Easy3	ArrayImplementation+2	No attempts yet	1s	1024 MB	Judgeable
LjetoGiven a chronological list of sprays between opposing players, score 100 per spray plus 50 when the same player sprays again within 10 seconds.	Easy3	SimulationImplementation+2	No attempts yet	1s	512 MB	Judgeable
Kick StartGiven a list of 2019 Kick Start dates and today's date, print the earliest scheduled date after today, or a message if none remain.	Easy3	ImplementationSorting+2	No attempts yet	1s	256 MB	Judgeable
IQPair 2n numbers into n pairs so the difference between the largest and smallest pair sums is minimized, and print that difference.	Easy3	SortingGreedy+2	No attempts yet	1s	64 MB	Judgeable
Quadratic equationGiven a nonzero integer Y, output nonzero integer coefficients A, B, C with absolute value at most 10^6 such that AY^2 + BY + C = 0.	Easy3	MathImplementation+1	No attempts yet	2s	256 MB	Judgeable
Deja vu of Go PlayersRed moves first and each player can empty one of their own piles per turn; decide whether red can always force a win.	Easy3	Game theoryImplementation	No attempts yet	1s	256 MB	Judgeable
Transform the StringFor each test case, find the minimum number of cyclic alphabet steps needed to turn every letter of S into some letter present in F.	Easy3	StringBrute force+2	No attempts yet	Not set	1024 MB	Judgeable
WardsGiven a letter grid split into regions and a move log with ward placements, print which cells Hanbyeol can see.	Easy3	BFSSimulation+1	No attempts yet	2s	1024 MB	Judgeable
Turning KnobsStarting from angle A0, find the total degrees turned when moving through angles A1..AN, each step choosing the shorter of the two rotation directions on a 360-degree circle.	Easy3	ImplementationMath+2	No attempts yet	1s	1024 MB	Judgeable
Drawing a Snail - ㅂGiven N, print the ㅂ-shaped snail figure scaled so each cell of the 5x5 shape is N by N characters.	Easy3	ImplementationSimulation+2	No attempts yet	1s	512 MB	Judgeable
Drawing Snail - Rotated ㅈGiven a cell size N, print a fixed 5 by 5 rotated ㅈ snail shape where each cell is drawn N times larger.	Easy3	ImplementationSimulation	No attempts yet	1s	512 MB	Judgeable
RotationRotate an integer by moving its units digit to the front repeatedly until the original returns, and print the sum of all rotations seen.	Easy3	MathSimulation+2	No attempts yet	1s	512 MB	Judgeable
WiFiGiven the study room's public WiFi and each room's hotspot, compute the public signal speed in every room and print the maximum, or IMPOSSIBLE if none is positive.	Easy3	ImplementationMath+2	No attempts yet	1s	512 MB	Judgeable
Sequence (Easy)Given a sequence of positive integers, sum A_i times A_j over every pair i < j and print the result modulo 1,000,000,007.	Easy3	MathPrefix sum+2	No attempts yet	1s	512 MB	Judgeable
DecalcomaniaGiven an N by M grid of paint letters and dots, fold it in half left to right and print the result, letting each cell keep the paint where the two halves meet.	Easy3	ImplementationArray+2	No attempts yet	1s	1024 MB	Judgeable
Algorithm Class - Selection Sort 1Simulate selection sort on an array of N distinct positive integers and report the two values swapped at the K-th swap, or -1 if fewer than K swaps occur.	Easy3	SortingSimulation+2	No attempts yet	1s	512 MB	Judgeable
AlpsooGiven a positive integer, decide whether its digit sequence rises then falls, with no flat step, and each slope kept constant within its part.	Easy3	ImplementationString+1	No attempts yet	1s	512 MB	Judgeable
AllocationGiven house prices and a budget B, find the maximum number of houses you can buy without exceeding B.	Easy3	GreedySorting	No attempts yet	15s	1024 MB	Judgeable
CountdownCount how many contiguous subarrays of length K equal the descending run K, K-1, ..., 2, 1.	Easy3	ArraySliding window+1	No attempts yet	20s	1024 MB	Judgeable
Record BreakerCount days whose visitor count beats every earlier day and also beats the next day, with the last day allowed to skip the next-day check.	Easy3	ArrayImplementation+1	No attempts yet	20s	1024 MB	Judgeable
Longest ArithmeticGiven an array, find the length of the longest contiguous subarray whose consecutive differences are all equal.	Easy3	ArrayImplementation+1	No attempts yet	20s	1024 MB	Judgeable
Maximum CoinsEach move goes diagonally down-right or up-left, so a path stays on one diagonal of the matrix; find the diagonal with the largest sum of coins.	Easy3	ArrayPrefix sum+2	No attempts yet	20s	1024 MB	Judgeable