Math and counting

Number theory, combinatorics, and geometry

Under construction

Still being built. Things may change

Total results13,164 problems

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
Musical Chairs
Easy3
Simulation, Implementation+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
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
Progressive Scramble
Easy3
Implementation, Math+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
Davor's Travel Fund
Easy3
Brute force, Math+1
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Blocked Billboard II
Easy3
Geometry, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Accepted ratio
Easy3
Implementation, Hash map+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
N and M (2)
Easy3
Backtracking, Recursion+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
2018 Yonsei University Programming Contest
Easy3
Math, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tile Filling 4
Easy3
Math, Greedy+1
No attempts yet
Time limit
0.1s
Memory limit
512 MB
Judgeable
Ordered Pairs
Easy3
Math, Number theory+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Duplicated number
Easy3
Math
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Beondegi
Easy3
Math, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Round and Round Snail
Easy3
Implementation, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Multiply and Divide
Easy3
Math, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Blue Flag, White Flag
Easy3
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Are the power strips enough?
Easy3
Greedy, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Sejin's Group Date
Easy3
Combinatorics, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
A/B to 2000 decimal places
Easy3
Math, Implementation+1
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Sum of Subrectangle Areas
Easy3
Math, Combinatorics
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Virus Outbreak
Easy3
Math, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Ninety-nine
Easy3
Game theory, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
The Answer Is Isugeun!
Easy3
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Math Is PE
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Badly implemented sieve of Eratosthenes
Easy3
Math, Number theory+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Yet Another No-Solve Prevention Problem!!
Easy3
Bit manipulation, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Ukje Is the Architecture King!!
Easy3
Geometry, Implementation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Baby Sukhwan Tururu Turu
Easy3
Implementation, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Kth Prime Number
Easy3
Number theory, Math+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Finding the Modular Inverse
Easy3
Number theory, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Factorial
Easy3
Number theory, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Calculating Ages
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Nadan
Easy3
Greedy, Math+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Spreadsheets
Easy3
Math, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Farm
Easy3
Math, Implementation
No attempts yet
Time limit
0.1s
Memory limit
512 MB
Judgeable
Appalling Architecture
Easy3
Array, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Treehouses
Easy3
Minimum spanning tree, Union-find+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Heir's Dilemma
Easy3
Brute force, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Professor Na's Bad Handwriting
Easy3
Implementation, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
A Homogeneous Country
Easy3
Hash map, Math
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Measuring the Height of a Cup Noodle
Easy3
Math, Geometry
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Let's Construct! - ②
Easy3
Math, Geometry+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
One Lap Around the Playground
Easy3
Math, Geometry+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Paper Folding
Easy3
Array, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Alpha Tic-Tac-Toe
Easy3
Game theory, Recursion+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Aligned Typesetting
Easy3
String, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Multinomial Coefficient
Easy3
Dynamic programming, Combinatorics
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
ICPC
Easy3
Implementation, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Chaarshanbegaan at Cafebazaar
Easy3
Math, Implementation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Social Game
Easy3
Math, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Manhattan
Easy3
Geometry, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Harshad Numbers
Easy3
Math, Brute force
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Half Seasoned, Half Fried
Easy3
Math, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Strong Password
Easy3
String, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
License Plate 1
Easy3
Combinatorics, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
License Plate 2
Easy3
Dynamic programming, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Flipper
Easy3
Simulation, Implementation+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Sleepy Cow Herding (Bronze)
Easy3
Greedy, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Lun
Easy3
Implementation, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Word Clock
Easy3
Implementation, String+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Sum of Multiples
Easy3
Implementation, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Total Number of Counts
Easy3
Math, Simulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Constructing a Cyclic Quadrilateral
Easy3
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Passing the Buck
Easy3
Matrix, Implementation+2
No attempts yet
Time limit
0.1s
Memory limit
256 MB
Judgeable
Good Day Bad Day
Easy3
Probability, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Payment Helper for the Moon Rabbit
Easy3
Dynamic programming, Greedy+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Fruit Stealing
Easy3
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Integral of a Polynomial
Easy3
String, Implementation+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Sam-sam Number
Easy3
Math, Implementation+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Sam-Sam-Han Number 2
Easy3
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
League of Legensal (Small)
Easy3
Dynamic programming, Combinatorics
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
I am Groot
Easy3
Simulation, Implementation+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Yumi
Easy3
Brute force, Geometry+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
What if a car takes the side of its owner, Kim Pyojun?
Easy3
Array, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
N! mod P (2)
Easy3
Implementation, Math
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Star Fruit
Easy3
Greedy, Math+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Floor Plan
Easy3
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Hexagonal Rooks
Easy3
Implementation, Brute force+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Hamster Ball
Easy3
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Gerrymandering
Easy3
Implementation, Math+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Interesting Number
Easy3
Math, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Jazz it Up!
Easy3
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Beer Bill
Easy3
Implementation, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Clock
Easy3
Math, Geometry+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Joint Attack
Easy3
Math, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Pongdang Pongdang 2
Easy3
Math, Implementation+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Pongdang Pongdang 1
Easy3
Math, Implementation+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Climbing Stairs
Easy3
Math, Implementation+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Expeditious Cubing
Easy3
Math, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
NBA Draft
Easy3
Implementation, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
solved.ac
Easy3
Sorting, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Summer Hand Fan
Easy3
Math, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Are They All Integers?
Easy3
Brute force, Math+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Thue-Morse String
Easy3
Bit manipulation, Math+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
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
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
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
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
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
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
Davor's Travel FundFind X and K so that 52 weeks of daily deposits, rising by K each day from Monday, total exactly N, maximizing X first and minimizing K.	Easy3	Brute forceMath+1	No attempts yet	1s	64 MB	Judgeable
Blocked Billboard IIGiven two axis-aligned rectangles, find the smallest rectangle that covers the first billboard minus the part hidden by the second.	Easy3	GeometryImplementation+2	No attempts yet	2s	512 MB	Judgeable
Accepted ratioGiven a submission log, ignore the administrator, count solvers and the rejections each made before their first accepted submission, then print the accepted ratio with 10 decimals.	Easy3	ImplementationHash map+2	No attempts yet	2s	512 MB	Judgeable
N and M (2)Print all ascending sequences of M distinct numbers chosen from 1 to N, in lexicographic order.	Easy3	BacktrackingRecursion+1	No attempts yet	1s	512 MB	Judgeable
2018 Yonsei University Programming ContestGiven the total spark count N of a firework that bursts once then bursts again, find the branching factor K.	Easy3	MathImplementation+2	No attempts yet	1s	128 MB	Judgeable
Tile Filling 4Find the maximum number of 2x1 and 1x2 dominoes that fit on an N by M wall without overlap.	Easy3	MathGreedy+1	No attempts yet	0.1s	512 MB	Judgeable
Ordered PairsCount the ordered pairs of natural numbers whose product equals a given N.	Easy3	MathNumber theory+2	No attempts yet	0.5s	512 MB	Judgeable
Duplicated numberA size-N array contains 1..N-1 with one value M repeated; find M.	Easy3	Math	No attempts yet	2s	256 MB	Judgeable
BeondegiGiven A players in a circle and a chant pattern by rounds, find who makes the T-th call of a chosen word (ppeon or degi), counting only that word.	Easy3	MathImplementation+2	No attempts yet	1s	128 MB	Judgeable
Round and Round SnailA snail walks a clockwise square spiral from the origin, one cell per second; given n seconds, print its coordinates.	Easy3	ImplementationSimulation+2	No attempts yet	1s	128 MB	Judgeable
Multiply and DivideGiven three integers in fixed order, insert one multiplication and one division sign to maximize the value, evaluated left to right.	Easy3	MathImplementation+2	No attempts yet	1s	128 MB	Judgeable
Blue Flag, White FlagEach of N players flips every flag whose number is a multiple of their index; count how many flags end white side up.	Easy3	MathNumber theory+2	No attempts yet	1s	128 MB	Judgeable
Are the power strips enough?Given K power strips with 3 to 8 sockets each, each strip can power at most half its sockets since adjacent sockets cannot both be used; decide if the total reaches N.	Easy3	GreedyMath+1	No attempts yet	1s	512 MB	Judgeable
Sejin's Group DateGiven N men and M women (M <= N), count the number of M-element subsets of men that could be paired with the women, modulo 1000000007.	Easy3	CombinatoricsMath+2	No attempts yet	1s	512 MB	Judgeable
A/B to 2000 decimal placesPrint A/B with exactly 2000 digits after the decimal point, truncating rather than rounding.	Easy3	MathImplementation+1	No attempts yet	0.5s	512 MB	Judgeable
Sum of Subrectangle AreasFor each N, compute the total area of all axis-aligned integer subrectangles in an N by N grid.	Easy3	MathCombinatorics	No attempts yet	2s	512 MB	Judgeable
Virus OutbreakRead hour values until -1 and print the Fibonacci number a(X) for each in the format 'Hour X: Y cow(s) affected'.	Easy3	MathDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Ninety-nineTwo players take turns adding 1 or 2 to a running count that starts at 1 or 2, and the task is to write a program that picks the start and moves so you say 99 first.	Easy3	Game theoryMath	No attempts yet	1s	1024 MB	Judgeable
The Answer Is Isugeun!Given integer coefficients A, B, C, classify the roots of Ax^2 + Bx + C = 0 as powers of two, integer roots, or neither.	Easy3	MathNumber theory+2	No attempts yet	2s	256 MB	Judgeable
Math Is PEThe bottom row of a staircase of 1x1 squares has n squares; output the perimeter shown by the solid line.	Easy3	MathImplementation	No attempts yet	1s	512 MB	Judgeable
Badly implemented sieve of EratosthenesCount how many times the inner statement runs in a nested loop where the outer index i goes from 1 to n and the inner step is i, for n up to 10^9.	Easy3	MathNumber theory+1	No attempts yet	1s	512 MB	Judgeable
Yet Another No-Solve Prevention Problem!!For each of Q queries, decide whether the given number a is a power of two, printing 1 for yes and 0 for no.	Easy3	Bit manipulationMath+2	No attempts yet	2s	512 MB	Judgeable
Ukje Is the Architecture King!!Given the vertices of an axis-aligned orthogonally convex polygon in order, output its perimeter.	Easy3	GeometryImplementation+1	No attempts yet	2s	512 MB	Judgeable
Baby Sukhwan Tururu TuruFind the N-th word of a repeating song whose tururu runs grow by one extra ru each repetition, with long runs printed in a compressed form.	Easy3	ImplementationMath+2	No attempts yet	1s	512 MB	Judgeable
Kth Prime NumberGiven K up to 500,000, print the K-th prime number.	Easy3	Number theoryMath+1	No attempts yet	2s	256 MB	Judgeable
Finding the Modular InverseGiven coprime positive integers a and m, find the smallest positive x with a*x congruent to 1 modulo m.	Easy3	Number theoryMath+2	No attempts yet	1s	512 MB	Judgeable
FactorialGiven N and a prime A, find the largest k such that A^k divides N! (the exponent of A in the prime factorization of N!).	Easy3	Number theoryMath+1	No attempts yet	1s	512 MB	Judgeable
Calculating AgesGiven a birth date and a reference date, compute the person's full, counting, and year ages on the reference date.	Easy3	MathImplementation	No attempts yet	1s	128 MB	Judgeable
NadanSplit K into N distinct positive integers that sum to K, and print one such distribution.	Easy3	GreedyMath+2	No attempts yet	1s	64 MB	Judgeable
SpreadsheetsConvert a column index up to 1e9 into a base-26 name like A, Z, AA, using letters with no zero digit.	Easy3	MathString+2	No attempts yet	2s	512 MB	Judgeable
FarmGiven feed rates a and b, animal count n, and total feed w, find the sheep and goat counts, or print -1 if the answer is missing or not unique.	Easy3	MathImplementation	No attempts yet	0.1s	512 MB	Judgeable
Appalling ArchitectureGiven a grid of filled 1x1 boxes forming one grounded component, compare the center of gravity's x-coordinate with the leftmost and rightmost ground-contact x to say left, balanced, or right.	Easy3	ArrayMath+1	No attempts yet	1s	512 MB	Judgeable
TreehousesConnect all treehouse points plus the first e ground access points by cables of minimum total length, given some cables already exist; output the added length as a MST problem.	Easy3	Minimum spanning treeUnion-find+2	No attempts yet	2s	512 MB	Judgeable
Heir's DilemmaCount six-digit numbers between L and H whose digits are nonzero and distinct and that are divisible by each of their own digits.	Easy3	Brute forceMath+1	No attempts yet	2s	512 MB	Judgeable
Professor Na's Bad HandwritingReplace every 0 and 6 digit with 9 in each score, cap at 100, then print the integer nearest the average, breaking ties upward.	Easy3	ImplementationMath+1	No attempts yet	1s	512 MB	Judgeable
A Homogeneous CountryCount class label frequencies over up to 100,000 lines and compute 1 minus the sum of squared relative frequencies.	Easy3	Hash mapMath	No attempts yet	1s	256 MB	Judgeable
Measuring the Height of a Cup NoodleGiven two parallel base diameters D1, D2 and the slanted side K of an isosceles trapezoid, compute the squared height.	Easy3	MathGeometry	No attempts yet	1s	512 MB	Judgeable
Let's Construct! - ②Given side lengths c of AB and b of AC, compute the ratio in which the internal angle bisector of angle A divides side BC.	Easy3	MathGeometry+1	No attempts yet	1s	512 MB	Judgeable
One Lap Around the PlaygroundCompute the perimeter of a track made of a rectangle between two semicircles, given the rectangle width and one semicircle radius, using pi = 3.141592.	Easy3	MathGeometry+1	No attempts yet	1s	512 MB	Judgeable
Paper FoldingGiven an N by N grid of numbers (N is a power of two), fold the paper in half repeatedly adding overlapping cells until one number remains; print it.	Easy3	ArrayMath+1	No attempts yet	1s	512 MB	Judgeable
Alpha Tic-Tac-ToeGiven a 3x3 tic-tac-toe board with X to move or O to move, find whether the side to move can force a win, a draw, or only a loss under perfect play.	Easy3	Game theoryRecursion+1	No attempts yet	1s	256 MB	Judgeable
Aligned TypesettingGiven an equal number of spaces between every pair of consecutive words, decide whether one such aligned typesetting has total length exactly L.	Easy3	StringMath+1	No attempts yet	2s	512 MB	Judgeable
Multinomial CoefficientGiven exponents n and m and a power k, compute the coefficient of x^k in (1+x+...+x^n)^m modulo 1,000,000,009.	Easy3	Dynamic programmingCombinatorics	No attempts yet	2s	256 MB	Judgeable
ICPCGiven the four goal counts from two-legged finals, apply aggregate scores and the away goals tiebreak to name the winner or output Penalty.	Easy3	ImplementationMath+1	No attempts yet	2s	512 MB	Judgeable
Chaarshanbegaan at CafebazaarGiven up to 100 dart coordinates, score each by its distance from the board center and print the total score.	Easy3	MathImplementation+1	No attempts yet	2s	512 MB	Judgeable
Social GameGiven A, B, C, find the fewest logins that yield at least C coins, counting A per login plus B per full Mon-to-Sun week.	Easy3	MathGreedy+2	No attempts yet	2s	512 MB	Judgeable
ManhattanGiven the Euclidean distance between two grid-aligned houses, find the maximum Manhattan distance achievable between them.	Easy3	GeometryMath+1	No attempts yet	1s	512 MB	Judgeable
Harshad NumbersFind the smallest number at least n that is divisible by its digit sum, for n up to 1,000,000,000.	Easy3	MathBrute force	No attempts yet	2s	512 MB	Judgeable
Half Seasoned, Half FriedGiven prices for seasoned, fried, and half-and-half chicken, find the cheapest way to get at least X seasoned and Y fried pieces.	Easy3	MathGreedy+2	No attempts yet	2s	512 MB	Judgeable
Strong PasswordGiven a string S, find the minimum number of characters to append so it has length at least 6 and contains a digit, a lowercase letter, an uppercase letter, and a special character.	Easy3	StringGreedy+2	No attempts yet	2s	512 MB	Judgeable
License Plate 1Given a format string of length at most 4 with c for letter and d for digit, count plates where no two adjacent characters are identical.	Easy3	CombinatoricsMath+2	No attempts yet	1s	512 MB	Judgeable
License Plate 2Count strings matching a pattern of letter and digit slots, where no two adjacent characters are equal, modulo 1,000,000,009.	Easy3	Dynamic programmingMath+2	No attempts yet	1s	512 MB	Judgeable
FlipperStart with the grid 1 2 / 3 4 and apply a sequence of horizontal (H) and vertical (V) flips, then print the final grid.	Easy3	SimulationImplementation+1	No attempts yet	1s	512 MB	Judgeable
Sleepy Cow Herding (Bronze)Three cows on a number line move one endpoint at a time; find the minimum and maximum moves to make their three positions consecutive.	Easy3	GreedyMath+2	No attempts yet	2s	512 MB	Judgeable
LunGiven a card number string with one digit replaced by 'x', find the smallest digit for 'x' that makes the number pass the Luhn check.	Easy3	ImplementationMath+2	No attempts yet	1s	512 MB	Judgeable
Word ClockConvert an hour and minute into the words a word clock shows, using past or to and special phrases for 0, 15, 30, and 45 minutes.	Easy3	ImplementationString+2	No attempts yet	0.5s	512 MB	Judgeable
Sum of MultiplesGiven N and a list of divisors K_i, sum every integer from 1 to N that is divisible by at least one K_i, counting each qualifying number once.	Easy3	ImplementationMath+1	No attempts yet	1s	512 MB	Judgeable
Total Number of CountsGiven N bills and bundle size M, repeatedly count items and group them into bundles of M until no bundle can form, then print the total number of counts.	Easy3	MathSimulation+2	No attempts yet	1s	512 MB	Judgeable
Constructing a Cyclic QuadrilateralGiven three decreasing segment lengths where the longest is a diameter of the circumscribed circle, find the fourth side of the cyclic quadrilateral or print -1.	Easy3	GeometryMath+2	No attempts yet	1s	512 MB	Judgeable
Passing the BuckGiven two 5x5 matrices A and B, compute each of five people's total workload by a fixed matrix formula and report the least busy person.	Easy3	MatrixImplementation+2	No attempts yet	0.1s	256 MB	Judgeable
Good Day Bad DayGiven a two-state Markov chain's transition probabilities and a starting mood, compute the probability of each mood N days later and print each scaled by 1000.	Easy3	ProbabilityDynamic programming+2	No attempts yet	1s	256 MB	Judgeable
Payment Helper for the Moon RabbitFind the minimum number of 1, 2, 5, and 7 won coins that sum to a given amount N.	Easy3	Dynamic programmingGreedy+1	No attempts yet	1s	256 MB	Judgeable
Fruit StealingCount the ways to distribute M identical stolen fruits among N labeled kinds so each kind receives at least one.	Easy3	CombinatoricsDynamic programming+1	No attempts yet	1s	256 MB	Judgeable
Integral of a PolynomialParse a degree-at-most-1 polynomial string and print its integral, writing x^2 as xx and the constant of integration as W.	Easy3	StringImplementation+2	No attempts yet	1s	256 MB	Judgeable
Sam-sam NumberDecide whether N can be written as a sum of distinct powers of 3, using each power at most once.	Easy3	MathImplementation+2	No attempts yet	1s	256 MB	Judgeable
Sam-Sam-Han Number 2Decide whether N can be written as a sum of distinct powers of 3, with at least one term, then print YES or NO.	Easy3	MathNumber theory+2	No attempts yet	1s	256 MB	Judgeable
League of Legensal (Small)Count sequences of 1-second A casts and M-second B casts that fill exactly N seconds, modulo 1,000,000,007.	Easy3	Dynamic programmingCombinatorics	No attempts yet	1s	256 MB	Judgeable
I am GrootGiven trunk length L and ratio R, branches double each level while length becomes floor(prev*R/100), stopping when a level's length is 5 or less; sum all branch lengths.	Easy3	SimulationImplementation+1	No attempts yet	1s	256 MB	Judgeable
YumiGiven Yumi's position and three fixed people on a plane, find the shortest travel distance for Yumi to visit all three people.	Easy3	Brute forceGeometry+1	No attempts yet	1s	256 MB	Judgeable
What if a car takes the side of its owner, Kim Pyojun?For each window length k from 1 to N, find the starting index of the length-k subarray with the largest standard deviation, breaking ties by the smallest index.	Easy3	ArrayPrefix sum+2	No attempts yet	1s	512 MB	Judgeable
N! mod P (2)Given N and a prime P with N < P, compute N! modulo P.	Easy3	ImplementationMath	No attempts yet	3s	1024 MB	Judgeable
Star FruitGiven summer length N, growth time T, C plots, and price P, compute the maximum money earnable by planting and replanting each plot as often as possible.	Easy3	GreedyMath+2	No attempts yet	1s	256 MB	Judgeable
Floor PlanGiven n, find non-negative integers m and k with n = m^2 - k^2, or report that no such pair exists.	Easy3	MathNumber theory+2	No attempts yet	1s	512 MB	Judgeable
Hexagonal RooksGiven a start and target cell on a side-6 hexagonal board, count the intermediate cells from which a rook reaches the target in exactly two moves.	Easy3	ImplementationBrute force+1	No attempts yet	1s	512 MB	Judgeable
Hamster BallTape can seal a ball only if its tape needed is at most the radius; each ball of radius s costs 2pis, so pick sizes with the cheapest cost per ball.	Easy3	GreedySorting+2	No attempts yet	1s	512 MB	Judgeable
GerrymanderingSum precinct votes into districts, find each district's winner, compute lost and excess wasted votes per party, then output the overall efficiency gap.	Easy3	ImplementationMath+2	No attempts yet	2s	1024 MB	Judgeable
Interesting NumberCount how many integers from 1 to N are divisible by the sum of their decimal digits.	Easy3	MathImplementation+2	No attempts yet	1s	512 MB	Judgeable
Jazz it Up!Given a squarefree n between 3 and 100000, find m with 2 <= m < n such that m*n is also squarefree.	Easy3	MathNumber theory+2	No attempts yet	1s	512 MB	Judgeable
Beer BillParse each bill line as either an item price with optional bars or a bars-only rake line, then print the total (beer at 42) rounded up to a multiple of 10 in the N,- format.	Easy3	ImplementationString+2	No attempts yet	2s	512 MB	Judgeable
ClockGiven a clock time, compute the angles each hand makes with 12 o'clock and report the smallest of the three pairwise angles.	Easy3	MathGeometry+2	No attempts yet	1s	512 MB	Judgeable
Joint AttackConvert a continued fraction given as coefficients into a single reduced fraction, with numerator and denominator under 10^18.	Easy3	MathImplementation+2	No attempts yet	1s	512 MB	Judgeable
Pongdang Pongdang 2Decide whether Hwisu raises an arm on turn T of a circular drinking game where the number of arms per turn cycles up and down between 1 and 2N.	Easy3	MathImplementation+1	No attempts yet	1s	256 MB	Judgeable
Pongdang Pongdang 1Given N players and a turn T, find how many arms must be raised on turn T as the count cycles 1,2,...,2N,2N-1,...,1 repeatedly.	Easy3	MathImplementation+1	No attempts yet	1s	256 MB	Judgeable
Climbing StairsGiven the required walk length n, the desk height r, and the office height k, find the minimum total steps walked in a day while starting and ending on the ground floor.	Easy3	MathImplementation+1	No attempts yet	1s	512 MB	Judgeable
Expeditious CubingGiven four of Claire's five solve times and a target final score (average of the middle three), find the largest fifth solve time that still meets the target, or report impossible or infinite.	Easy3	MathSorting+2	No attempts yet	2s	512 MB	Judgeable
NBA DraftClassify each player into one of four draft categories by comparing five integer statistics against expected ranges and their midpoints.	Easy3	ImplementationMath+2	No attempts yet	2s	512 MB	Judgeable
solved.acGiven up to 300,000 difficulty votes, output the 30% trimmed mean, rounding the count trimmed at each end and the final average to the nearest integer.	Easy3	SortingMath+1	No attempts yet	1s	1024 MB	Judgeable
Summer Hand FanFor each fan compute the price plus the sum C + 2C + ... + mC for the number of K-hour intervals fully completed during the walk Q, then output the cheapest fan index.	Easy3	MathImplementation+2	No attempts yet	1s	1024 MB	Judgeable
Are They All Integers?Decide whether (A[i]-A[j])/A[k] is an integer for every choice of three distinct indices in a sorted list.	Easy3	Brute forceMath+2	No attempts yet	2s	1024 MB	Judgeable
Thue-Morse StringFind the character at position k in the Thue-Morse sequence, where k can be as large as 10^18.	Easy3	Bit manipulationMath+1	No attempts yet	1s	256 MB	Judgeable