Math and counting

Number theory, combinatorics, and geometry

Under construction

Still being built. Things may change

Total results13,164 problems

Deja vu of Go Players
Easy3
Game theory, Implementation
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Turning Knobs
Easy3
Implementation, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 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
Retype
Easy3
Math, Implementation+1
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
ZOAC 4
Easy3
Greedy, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Zathras
Easy3
Simulation, Implementation+2
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Impartial Offerings
Easy3
Sorting, Greedy+2
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Contest
Easy3
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Mind Reading
Easy3
Math, Implementation+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Chopsticks
Easy3
Math, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
What makes 2022 special?
Easy3
Math, Brute force
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Garden
Easy3
Math, Implementation
No attempts yet
Time limit
0.1s
Memory limit
1024 MB
Judgeable
Book Covers
Easy3
Implementation, Math+1
No attempts yet
Time limit
0.5s
Memory limit
1024 MB
Judgeable
Guess the digit
Easy3
Brute force, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
РАВЕНСТВО
Easy3
Math, Implementation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Painting the Fence
Easy3
Intervals, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
ДИНИ
Easy3
Brute force, Array+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Algorithm Class - Asymptotic Notation 2
Easy3
Math, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Algorithm Class - Asymptotic Notation 3
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
ИЗРАЗ
Easy3
Brute force, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Game
Easy3
Array, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Two's Complement
Easy3
Bit manipulation, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Microwave Again?
Easy3
Greedy, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Mult!
Easy3
Implementation, Simulation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Algorithm Class - Fibonacci Number 2
Easy3
Math, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Algorithm Class - Matrix Path Problem 1
Easy3
Dynamic programming, Recursion+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Encryption Matrix
Easy3
Matrix, Brute force+1
No attempts yet
Time limit
0.8s
Memory limit
512 MB
Judgeable
Good Fours and Good Fives
Easy3
Math, Brute force+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Code Guessing
Easy3
Brute force, Implementation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Fences
Easy3
Geometry, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Follow the Trace!
Easy3
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Anno Domini 2022
Easy3
Implementation, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sequinary Numerals
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Social Distancing
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Ticket Completed?
Easy3
Union-find, Graph+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Ornaments
Easy3
Math, Geometry
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Cracking RSA
Easy3
Math, Number theory+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Cookie Cutters
Easy3
Geometry, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Railroad
Easy3
Math, Graph
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Challenge Nine
Easy3
Math, String+1
No attempts yet
Time limit
Not set
Memory limit
1024 MB
Judgeable
Computational ethnography
Easy3
Brute force, Math
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Is It Even?
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Invested Money
Easy3
Implementation, Math
No attempts yet
Time limit
0.1s
Memory limit
1024 MB
Judgeable
Bottle Arrangements
Easy3
Greedy, Math+1
No attempts yet
Time limit
2s
Memory limit
2048 MB
Judgeable
Infinity Area
Easy3
Simulation, Math
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Palindromic Factors
Easy3
Math, Number theory
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Period
Easy3
String, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Hungry Ari Buys a Sandwich
Easy3
Bit manipulation, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Clean Sequence (Easy)
Easy3
Math, Combinatorics
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Ensemble Gomgom
Easy3
Probability, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Gahee and the Chaos Papulatus
Easy3
Simulation, Implementation+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
solved.ac 2022 difficulty rating
Easy3
Implementation, Math
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Buying Pants
Easy3
Math, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Planetary Alignment
Easy3
Math, Number theory
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Beat the Card Product
Easy3
Brute force, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Count the Products of Card Numbers
Easy3
Math, Brute force
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Dividing the Digits of an Integer in Base k
Easy3
Implementation, Math
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Turn Integer A into K
Easy3
Greedy, Math
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Sports Day
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Ad Astra
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Baduk Stone Game
Easy3
Math, Simulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Bead Bracelet String Length
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Simplified Calendar System
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Pseudo Pseudo Random Numbers
Easy3
Dynamic programming, Combinatorics
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
How Much Coffee is Left?
Easy3
Math, Geometry
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sum of Sums of Squared Binomial Coefficients
Easy3
Math, Combinatorics
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Give-a-Gnocchi
Easy3
Number theory, Simulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Rounding Many Ways
Easy3
Number theory, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Simple Darts
Easy3
Geometry, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Balanced Strings
Easy3
Implementation, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Hash Hacking
Easy3
Math, Number theory
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
DPS
Easy3
Combinatorics, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sugar Delivery 2
Easy3
Math, Greedy
No attempts yet
Time limit
0.25s
Memory limit
1024 MB
Judgeable
Artificial Elements
Easy3
Number theory, Brute force
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Sorry About That, Chief!
Easy3
Number theory, Brute force
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Neighbor
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Orient the Edges
Easy3
Math, Combinatorics
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Painting Houses
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Second Numbers
Easy3
Math, Number theory+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
The Bus Card
Easy3
Greedy, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
The Will Rogers Phenomenon
Easy3
Brute force, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Clock
Easy3
Math, Implementation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Alignment of the Planets
Easy3
Geometry, Brute force+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Max Factor
Easy3
Number theory, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Long Multiplication
Easy3
Implementation, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Negative Number Bases
Easy3
Math, Simulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Dissimilar numbers
Easy3
Math, Brute force
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Class
Easy3
Math, Greedy
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Against Bertrand's Postulate
Easy3
Sorting, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Distinct Squares
Easy3
Math, Binary search
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Pairs
Easy3
Brute force, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Number of Divisors
Easy3
Brute force, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Catalan Master's Segment Drawing Game
Easy3
Game theory, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Fraction Finding 2
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Factorial 4
Easy3
Math, Implementation
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Math Quiz
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sum of Two Numbers
Easy3
Math, Greedy
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sum of Primes
Easy3
Dynamic programming, Number theory
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
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
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
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
RetypeGiven N levels, current level K, and sword level S, compare restarting from level 1 against walking back to S, and report the smaller total time including time already spent.	Easy3	MathImplementation+1	No attempts yet	20s	1024 MB	Judgeable
ZOAC 4Given an H by W grid, place as many people as possible so any two differ by more than N rows or more than M columns.	Easy3	GreedyMath+1	No attempts yet	1s	512 MB	Judgeable
ZathrasSimulate a yearly update of two robot populations, applying pairing, births with percentages, and 1% decommissioning, for Y years.	Easy3	SimulationImplementation+2	No attempts yet	20s	1024 MB	Judgeable
Impartial OfferingsAssign each pet a treat count so equal sizes get equal counts and larger sizes get strictly more, minimizing the total treats.	Easy3	SortingGreedy+2	No attempts yet	10s	1024 MB	Judgeable
ContestParse a contest log in time order and compute each participant's total score using the per-problem formula with wrong-answer penalties.	Easy3	SimulationImplementation+2	No attempts yet	1s	1024 MB	Judgeable
Mind ReadingSimulate arithmetic operations on a symbolic expression a*x + b, then check whether a equals 0 and b is an integer.	Easy3	MathImplementation+1	No attempts yet	2s	1024 MB	Judgeable
ChopsticksGiven N kinds of chopsticks in unlimited supply, find how many must be drawn to guarantee R pairs in the worst case.	Easy3	MathCombinatorics+2	No attempts yet	1s	512 MB	Judgeable
What makes 2022 special?Given N and base d, find the smallest number above N whose base-d digits are each of 0 to d-1 used exactly once.	Easy3	MathBrute force	No attempts yet	1s	1024 MB	Judgeable
GardenGiven two rectangles stacked with their left sides aligned, count the 1x1 tiles that surround the bed, corners included.	Easy3	MathImplementation	No attempts yet	0.1s	1024 MB	Judgeable
Book CoversGiven a textbook and two covers, each described by two sides in centimeters and millimeters, pick the fitting cover with the smallest width, or report none.	Easy3	ImplementationMath+1	No attempts yet	0.5s	1024 MB	Judgeable
Guess the digitGiven an equation with one +, - or * and numbers containing ? placeholders, find the smallest digit (distinct from given digits) that makes it true, or print mistake.	Easy3	Brute forceImplementation+2	No attempts yet	1s	1024 MB	Judgeable
РАВЕНСТВОGiven positive integers a, b, c with c < b and x guaranteed integer, compute x = (b - c) / a.	Easy3	MathImplementation+1	No attempts yet	1s	1024 MB	Judgeable
Painting the FenceGiven two painted segments [A,B] and [C,D] on a fence, find how many boards are painted at least once.	Easy3	IntervalsMath+1	No attempts yet	1s	1024 MB	Judgeable
ДИНИGiven four watermelon weights, split them between two hands so the absolute difference of the two sums is as small as possible.	Easy3	Brute forceArray+1	No attempts yet	1s	1024 MB	Judgeable
Algorithm Class - Asymptotic Notation 2Given f(n) = a1n + a0 and constants c, n0, decide whether cn <= f(n) holds for every n >= n0, printing 1 or 0.	Easy3	MathImplementation+2	No attempts yet	1s	512 MB	Judgeable
Algorithm Class - Asymptotic Notation 3Given f(n) = a1n + a0 and constants c1, c2, n0, decide whether c1n <= f(n) <= c2*n holds for every n >= n0.	Easy3	MathImplementation	No attempts yet	1s	512 MB	Judgeable
ИЗРАЗArrange three given non-negative integers and insert +, -, and * (each used once) to maximize the expression's value.	Easy3	Brute forceMath+2	No attempts yet	1s	1024 MB	Judgeable
GameGiven four boxes holding some of the numbers 1 to 4, output the numbers that must fill the empty boxes, or the first two box contents when none are empty.	Easy3	ArrayImplementation+2	No attempts yet	1s	1024 MB	Judgeable
Two's ComplementGiven N up to 10^9, count how many of the 32 bits differ between N and its 32-bit two's complement.	Easy3	Bit manipulationMath+1	No attempts yet	1s	512 MB	Judgeable
Microwave Again?Given a target cooking time as M:S, find the fewest presses of the 10 sec, 1 min, 10 min, and start buttons that set the timer to exactly that time.	Easy3	GreedyMath+1	No attempts yet	1s	512 MB	Judgeable
Mult!Scan a sequence of numbers and print each number that is a multiple of the first number of its current round, which then restarts the round.	Easy3	ImplementationSimulation+2	No attempts yet	1s	1024 MB	Judgeable
Algorithm Class - Fibonacci Number 2For a given n, count the base-case calls of recursive Fibonacci and the loop iterations of the DP version, each modulo 1e9+7.	Easy3	MathDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Algorithm Class - Matrix Path Problem 1Count how many times the base case of a recursive matrix path search runs versus the inner assignment of the dynamic programming version.	Easy3	Dynamic programmingRecursion+2	No attempts yet	1s	512 MB	Judgeable
Encryption MatrixGiven three N by N matrices, check all ordered pairs for which their product equals the third matrix, then output a bitmask score for each matrix based on whether it acts as plaintext, encryption matrix, or ciphertext.	Easy3	MatrixBrute force+1	No attempts yet	0.8s	512 MB	Judgeable
Good Fours and Good FivesCount the number of unordered ways to write N as a sum of 4s and 5s, or output 0 if no such sum exists.	Easy3	MathBrute force+1	No attempts yet	1s	1024 MB	Judgeable
Code GuessingGiven Alice's two digits and the table positions of the four sorted cards, decide whether Bob's two digits are uniquely determined and print them, else -1.	Easy3	Brute forceImplementation+1	No attempts yet	1s	1024 MB	Judgeable
FencesGiven an isosceles triangle formed by two ditches, find the apex angle at the short ditch's end and round it to the nearest degree.	Easy3	GeometryMath+1	No attempts yet	1s	512 MB	Judgeable
Follow the Trace!Given n integers, build a nonempty square matrix using each value at most as many times as it appears, and maximize the diagonal sum.	Easy3	GreedySorting+2	No attempts yet	1s	512 MB	Judgeable
Anno Domini 2022Given two years written as AD or BC, compute how many years passed between January 1 of the earlier year and January 1 of the later one, with no year 0.	Easy3	ImplementationMath+2	No attempts yet	2s	512 MB	Judgeable
Sequinary NumeralsConvert a sequinary numeral (base 3/2 digits 0 to 2, leading digit 1 or 2) to its value, printed as an integer or as a mixed number with a reduced fraction.	Easy3	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Social DistancingGiven S circular seats with N occupied, find how many more people can sit so that no two seated people are adjacent.	Easy3	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Ticket Completed?Count city pairs connected by claimed rail segments, then divide by the total number of unordered city pairs.	Easy3	Union-findGraph+1	No attempts yet	1s	1024 MB	Judgeable
OrnamentsGiven circle radius r, knot distance h, and extra percent s, compute the string length wrapped around the circle, rounded to two decimals.	Easy3	MathGeometry	No attempts yet	1s	1024 MB	Judgeable
Cracking RSAGiven an RSA public key (n, e) where n is a product of two primes below 1000, find the private exponent d.	Easy3	MathNumber theory+1	No attempts yet	3s	1024 MB	Judgeable
Cookie CuttersScale the polygon by sqrt(A divided by its area), then translate it so the minimum x and y coordinates are both zero.	Easy3	GeometryMath+1	No attempts yet	1s	1024 MB	Judgeable
RailroadGiven X level junctions and Y switches, decide whether they can form a closed track using every piece with no dead ends.	Easy3	MathGraph	No attempts yet	1s	1024 MB	Judgeable
Challenge NineInsert exactly one digit into N so the result is divisible by 9, then output the smallest such number without leading zeros.	Easy3	MathString+1	No attempts yet	Not set	1024 MB	Judgeable
Computational ethnographyCount the numbers from A to B whose digit reversal is also a perfect square, where both the number and its reversal are squares and the reversal has no leading zero.	Easy3	Brute forceMath	No attempts yet	1s	512 MB	Judgeable
Is It Even?Given N integers and K, decide whether the product of the integers is divisible by 2^K, printing 1 or 0.	Easy3	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Invested MoneyGiven today's weekday and how many days ago each deposit was made, find the fewest days until a deposit renews, where renewals never fall on weekends.	Easy3	ImplementationMath	No attempts yet	0.1s	1024 MB	Judgeable
Bottle ArrangementsConstruct a length-n string of R and W bottles so every requested (r,w) pair appears as the counts in some contiguous interval, or report IMPOSSIBLE.	Easy3	GreedyMath+1	No attempts yet	2s	2048 MB	Judgeable
Infinity AreaGiven R, A, B, sum the areas of circles whose radii alternate between multiplying by A and integer-dividing by B, until a radius reaches zero.	Easy3	SimulationMath	No attempts yet	20s	1024 MB	Judgeable
Palindromic FactorsCount the divisors of A that read the same forward and backward in decimal.	Easy3	MathNumber theory	No attempts yet	2s	1024 MB	Judgeable
PeriodGiven a repeating decimal 0.(digits) with the repeating block written three times, print its value as a fully reduced fraction, numerator then denominator.	Easy3	StringMath+1	No attempts yet	1s	1024 MB	Judgeable
Hungry Ari Buys a SandwichGiven a sandwich price S and Kugi's money M, decide whether Ari can pay alone, needs Kugi's coins, or cannot pay even with Kugi's help.	Easy3	Bit manipulationMath	No attempts yet	1s	1024 MB	Judgeable
Clean Sequence (Easy)Count the clean sequences of length 2N whose score is minimal, where N is at most 10.	Easy3	MathCombinatorics	No attempts yet	1s	1024 MB	Judgeable
Ensemble GomgomGiven N members who each pick one of K notes with equal probability, find the expected number of pairs that play the same note.	Easy3	ProbabilityMath	No attempts yet	1s	1024 MB	Judgeable
Gahee and the Chaos PapulatusGiven the clock time, zone percentages, and timed item and seal events, find the HP percentage Papulatus recovers when the pattern ends.	Easy3	SimulationImplementation+1	No attempts yet	1s	512 MB	Judgeable
solved.ac 2022 difficulty ratingGiven N timestamped difficulty opinions (levels 1 to 30), compute a weighted average where newer opinions and the 0.9 per-rank decay raise weight, rounded to an integer.	Easy3	ImplementationMath	No attempts yet	2s	1024 MB	Judgeable
Buying PantsCount the pants whose waist fits Siru's lower body circumference at a height equal to the pants' length, so the hem sits exactly at ground level.	Easy3	MathImplementation	No attempts yet	2s	1024 MB	Judgeable
Planetary AlignmentGiven the alignment periods T_1 to T_(N-2) for each triple of consecutive planets, find the period at which all N planets line up.	Easy3	MathNumber theory	No attempts yet	2s	1024 MB	Judgeable
Beat the Card ProductGiven n digits from 1 to 9, find a multiset of n digits from 1 to 9 with a larger product whose sorted concatenation is smallest, or print -1 if none exists.	Easy3	Brute forceMath+1	No attempts yet	1s	512 MB	Judgeable
Count the Products of Card NumbersGiven n, count the distinct products of n cards, each showing a digit from 1 to 9 with repetition allowed, where n is at most 7.	Easy3	MathBrute force	No attempts yet	1s	512 MB	Judgeable
Dividing the Digits of an Integer in Base kConvert n to base k, split its digits at each 0, and print the sum of the distinct nonempty pieces in base k.	Easy3	ImplementationMath	No attempts yet	1s	512 MB	Judgeable
Turn Integer A into KGiven A and K, find the minimum number of operations (add 1 or multiply by 2) needed to turn A into K.	Easy3	GreedyMath	No attempts yet	1s	512 MB	Judgeable
Sports DayGiven N teams of M members, a people still in the event, and K of them on Junhyeok's team, find the largest and smallest rank his team can have.	Easy3	MathImplementation	No attempts yet	1s	512 MB	Judgeable
Ad AstraCount workdays and weekend days among N dates on a custom calendar, plus the complete weekends between the first and last date.	Easy3	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Baduk Stone GameGiven N stones, find the fewest stones to add so the first player wins a game where turn k must remove exactly k stones.	Easy3	MathSimulation	No attempts yet	1s	1024 MB	Judgeable
Bead Bracelet String LengthFind the minimum total length of a closed loop through all N distinct numbers, where each string costs the absolute difference of its two endpoints.	Easy3	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Simplified Calendar SystemGiven a date in a 360-day calendar and its weekday, find the weekday of a later date.	Easy3	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Pseudo Pseudo Random NumbersCount the binary strings of length n that have no run of identical bits longer than k.	Easy3	Dynamic programmingCombinatorics	No attempts yet	1s	1024 MB	Judgeable
How Much Coffee is Left?Given a cone-frustum mug, the minutes already spent drinking, and the current coffee depth, find how many more minutes the rest of the coffee takes.	Easy3	MathGeometry	No attempts yet	1s	1024 MB	Judgeable
Sum of Sums of Squared Binomial CoefficientsFor each n from 3 to M, add the squares of the binomial coefficients C(n,k) over k from 0 to n, and print the total modulo 10^9+7.	Easy3	MathCombinatorics	No attempts yet	1s	512 MB	Judgeable
Give-a-GnocchiGiven n and k, output the kth composite number that is not divisible by any prime up to n.	Easy3	Number theorySimulation	No attempts yet	1s	1024 MB	Judgeable
Rounding Many WaysGiven N, list every X of the form 2^a * 5^b that divides N, since X must divide both 10^Z and N.	Easy3	Number theoryMath	No attempts yet	1s	1024 MB	Judgeable
Simple DartsGiven a circular board with w wedges and ring radii b, d, and s, sum the scores of each dart throw at (x, y) coordinates.	Easy3	GeometryImplementation	No attempts yet	1s	1024 MB	Judgeable
Balanced StringsCount the ways to fill each ? so that adjacent letters alternate between vowel and consonant, making the string balanced.	Easy3	ImplementationMath	No attempts yet	1s	1024 MB	Judgeable
Hash HackingCount the length-N sequences over M symbols whose weighted sum mod M equals H, printed modulo 1000000007.	Easy3	MathNumber theory	No attempts yet	1s	1024 MB	Judgeable
DPSCount the unordered groups of three people whose handle initials can be rearranged to spell the team name S.	Easy3	CombinatoricsMath+1	No attempts yet	1s	1024 MB	Judgeable
Sugar Delivery 2Find the fewest 3-kg and 5-kg bags that add up to exactly N kilograms, or report -1 if no combination works.	Easy3	MathGreedy	No attempts yet	0.25s	1024 MB	Judgeable
Artificial ElementsFor each atomic number up to 118, decide whether it can be written as the sum of two prime numbers.	Easy3	Number theoryBrute force	No attempts yet	1s	256 MB	Judgeable
Sorry About That, Chief!For each value from 2 to 10,000, report whether it is prime or how far it is from the nearest prime.	Easy3	Number theoryBrute force	No attempts yet	1s	1024 MB	Judgeable
NeighborGiven two fractions, reduce their positive difference and output it if the numerator is 1, otherwise output NOT NEIGHBORS.	Easy3	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Orient the EdgesCount the acyclic orientations of a complete graph on n labeled points, modulo 1000000007, for n up to 1,000,000.	Easy3	MathCombinatorics	No attempts yet	1s	1024 MB	Judgeable
Painting HousesGiven K, P, and X, find the minimum of m times X plus P times K divided by m over positive integers m, the number of painters.	Easy3	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Second NumbersGiven n, check whether its decimal digits can be split into two parts that are both primes without leading zeros.	Easy3	MathNumber theory+1	No attempts yet	2s	1024 MB	Judgeable
The Bus CardGiven a travel amount K in SEK, find the fewest card top-ups of 100, 200, or 500 SEK that cover at least K.	Easy3	GreedyMath	No attempts yet	1s	1024 MB	Judgeable
The Will Rogers PhenomenonGiven two groups of positive integers, find one number whose move to the other group raises the average of both groups, or report that none exists.	Easy3	Brute forceMath	No attempts yet	1s	1024 MB	Judgeable
ClockGiven the angle between the hour and minute hands in tenths of a degree, print the morning time that produces it as hh:mm.	Easy3	MathImplementation+1	No attempts yet	1s	1024 MB	Judgeable
Alignment of the PlanetsGiven N grid points, list every triple of points that lie exactly on one line, with IDs sorted within each triple and across the output.	Easy3	GeometryBrute force+1	No attempts yet	1s	1024 MB	Judgeable
Max FactorGiven N distinct serial numbers up to 20,000, find the one whose largest prime factor is greatest, breaking ties by input order.	Easy3	Number theoryImplementation	No attempts yet	1s	1024 MB	Judgeable
Long MultiplicationGiven two positive integers of up to 20 digits, print their long multiplication in the vertical layout, with each partial product and the final sum aligned.	Easy3	ImplementationMath	No attempts yet	1s	1024 MB	Judgeable
Negative Number BasesConvert the integer N to base B (negative bases allowed, from -10 to -2 and 2 to 10) and print its digits with no sign.	Easy3	MathSimulation	No attempts yet	1s	1024 MB	Judgeable
Dissimilar numbersGiven x and a range [l, r] of at most 1001 values, list every y in the range that differs from x and has gcd with x equal to 1 or a prime.	Easy3	MathBrute force	No attempts yet	1s	1024 MB	Judgeable
ClassGiven n boys and m girls seated two per desk, find the maximum number of students who sit alone or with a student of the other gender.	Easy3	MathGreedy	No attempts yet	1s	1024 MB	Judgeable
Against Bertrand's PostulateGiven n, find the longest run of consecutive composite numbers strictly between n and 2n, and output its endpoints l and r.	Easy3	SortingMath+2	No attempts yet	1s	1024 MB	Judgeable
Distinct SquaresGiven n unit squares, find the maximum number of distinct squares that can be built, where a square with side k uses k^2 units.	Easy3	MathBinary search	No attempts yet	1s	1024 MB	Judgeable
PairsSplit four given integers into two pairs and print the largest possible sum of the two pair products.	Easy3	Brute forceMath	No attempts yet	1s	1024 MB	Judgeable
Number of DivisorsGiven n, find the number from 1 to n that has the most divisors, and print that number with its divisor count.	Easy3	Brute forceMath	No attempts yet	1s	1024 MB	Judgeable
Catalan Master's Segment Drawing GameGiven N points on a circle, decide the winner of the non-crossing segment drawing game for both coin outcomes, P=0 and P=1.	Easy3	Game theoryMath	No attempts yet	1s	1024 MB	Judgeable
Fraction Finding 2Given X up to 10^18, find the X-th fraction when the infinite table is read in zigzag diagonal order.	Easy3	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Factorial 4Given N from 0 to 100,000, print N! exactly. The result has up to about 456,000 digits, so the program needs big-number multiplication.	Easy3	MathImplementation	No attempts yet	5s	1024 MB	Judgeable
Math QuizGiven N integers A_k, find real p and q so that the sum of omega^A_k equals p*omega + q, where omega is a root of x^2 + x + 1 = 0.	Easy3	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Sum of Two NumbersGiven n, the task is to split n into two non-negative parts x and y whose digit sums differ by at most 1.	Easy3	MathGreedy	No attempts yet	1s	1024 MB	Judgeable
Sum of PrimesCount the ways to write each query n as an unordered sum of primes, modulo 1,000,000,007, with up to 10,000 queries and n up to 100,000.	Easy3	Dynamic programmingNumber theory	No attempts yet	3s	128 MB	Judgeable