Math and counting

Number theory, combinatorics, and geometry

Under construction

Still being built. Things may change

Total results13,152 problems

Sumac Sequences
Easy2
Simulation, Math
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Unfriend
Easy2
Tree, Brute force+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
What is n, Daddy?
Easy2
Math, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
ISBN 1-3-Sum
Easy2
Math, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Good Times
Easy2
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Body Mass Index
Easy2
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Deal or No Deal Calculator
Easy2
Implementation, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Federal Voting Age
Easy2
Implementation, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Cell Sell
Easy2
Implementation, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Mouse Move
Easy2
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Squares
Easy2
Math, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Terms of Office
Easy2
Math, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Constrained Permutations
Easy2
Brute force, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fraction Action
Easy2
Math, Number theory+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Mod Inverse
Easy2
Number theory, Brute force
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Calendar
Easy2
Implementation, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cross-Number Puzzle
Easy2
Brute force, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Numbers
Easy2
Math, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Building Blocks
Easy2
Math, Brute force
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Entropy
Easy2
Hash map, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Expression
Easy2
String, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Right Triangle Check
Easy2
Math, Geometry+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Gauss
Easy2
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
StuPId
Easy2
Math, Implementation+1
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Sexagenary Cycle (干支)
Easy2
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cuboids
Easy2
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Divisibility
Easy2
Math, Number theory+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Teleprime
Easy2
Number theory, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Concert
Easy2
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ways to Make Rectangles
Easy2
Math, Brute force+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Polynomial
Easy2
Math, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Kamil
Easy2
Math, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Julka
Easy2
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Units Digit of a Power of Two
Easy2
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Caesar Cipher
Easy2
String, Array+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Non-Divisors
Easy2
Number theory, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sums and Differences
Easy2
Math, Combinatorics
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Step on the Foot
Easy2
Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Kwadrat
Easy2
Geometry, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Dividing the Chocolate Bar
Easy2
Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Overlapping Rectangle Area
Easy2
Geometry
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Little Snowman
Easy2
Math, Brute force
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bouncing Ball
Easy2
Math
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Making Grid Paper
Easy2
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Paints
Easy2
Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tournament
Easy2
Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Missing Digits
Easy2
Brute force, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Closing the Circuit
Easy2
Implementation, Sorting+1
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Mondays
Easy2
Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Rock Paper Scissors
Easy2
Probability, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bookmakers
Easy2
Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Power Strips
Easy2
Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Changing a Light Bulb
Easy2
Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Old Bill
Easy2
Brute force, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Clock
Easy2
Math, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Mathematical Curiosity
Easy2
Brute force, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Addition in Different Bases
Easy2
Implementation, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Air speed of a fully laden swallow
Easy2
Implementation, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sir Bedavere's Bogus Division
Easy2
Brute force, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Taunt Exposure Estimation
Easy2
Implementation, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Consecutive Digits in a Rational Number
Easy2
Simulation, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Check Digits
Easy2
Implementation, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Reducing Improper Fractions
Easy2
Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Geometric Inflation
Easy2
Simulation, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Arithmetic and Geometric Sums
Easy2
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Monitor DPI
Easy2
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fast Food Prizes
Easy2
Greedy, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Zombie Invasion
Easy2
Simulation, Math
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Von Neumann
Easy2
Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The n Days of Christmas
Easy2
Math, Implementation
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Long is a train, a train is fast, fast is a plane
Easy2
Implementation, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Perfect Number Check
Easy2
Number theory, Implementation
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Kids love candy
Easy2
Math, Greedy
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Combination Lock
Easy2
Brute force, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Vicinity
Easy2
Brute force, Geometry
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Stone Game 5
Easy2
Game theory, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Anti-Arithmetic Permutation
Easy2
Brute force, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fibonacci remainder
Easy2
Math, Simulation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Qurban 2011
Easy2
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bee
Easy2
Implementation, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Extending Goldbach's Conjecture
Easy2
Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The King
Easy2
Greedy, Math
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Rectangle intersection
Easy2
Geometry, Intervals
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Euclid
Easy2
Number theory
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Zeros in a Factorial
Easy2
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Euclidean Algorithm
Easy2
Simulation, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Centroid of Point Masses
Easy2
Math, Implementation
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Polar Explorer
Easy2
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Microwave Buttons
Easy2
Greedy, Math
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Focal Length of a Lens
Easy2
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Aligned Calendar
Easy2
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Tax Rate Changed
Easy2
Brute force, Math
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Dice Game
Easy2
Probability, Brute force
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Runway Planning
Easy2
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Ice Bucket Challenge
Easy2
Math
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Headshot
Easy2
Probability, String
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Radix 32 Conversion
Easy2
Math, String
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Growling Gears
Easy2
Math
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Triples
Easy2
Brute force, Math
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Joy of Flight
Easy2
Implementation, Simulation+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Sumac SequencesStarting from two integers, repeatedly replace the pair with (second, first minus second) until the difference turns negative and report how many terms appear.	Easy2	SimulationMath	No attempts yet	2s	512 MB	Judgeable
UnfriendCount the subsets of nodes in a rooted tree that can be removed, where removing a node forces removal of all its descendants.	Easy2	TreeBrute force+1	No attempts yet	2s	512 MB	Judgeable
What is n, Daddy?Count the ordered pairs (a, b) with 1 <= b <= a <= 5 and possibly a single hand, summing to n.	Easy2	MathBrute force+2	No attempts yet	2s	512 MB	Judgeable
ISBN 1-3-SumGiven the last three digits of an ISBN starting with 9780921418, compute the 1-3-sum and print it.	Easy2	MathImplementation+1	No attempts yet	1s	128 MB	Judgeable
Good TimesGiven the time in Ottawa as hour*100+minute, print the local time in seven Canadian cities using fixed offsets, wrapping across midnight.	Easy2	MathImplementation	No attempts yet	1s	128 MB	Judgeable
Body Mass IndexRead a weight and a height, compute weight divided by height squared, and print the BMI category.	Easy2	MathImplementation	No attempts yet	1s	128 MB	Judgeable
Deal or No Deal CalculatorRead eliminated case numbers and a Banker's offer, compute the average of the remaining amounts, and print deal if the offer is higher, otherwise no deal.	Easy2	ImplementationArray+1	No attempts yet	1s	128 MB	Judgeable
Federal Voting AgeFor each birth date, decide whether the person is at least 18 years old on February 27, 2007.	Easy2	ImplementationMath	No attempts yet	1s	128 MB	Judgeable
The Cell SellGiven daytime, evening, and weekend minutes, compute the monthly cost under two phone plans and print the cheaper one.	Easy2	ImplementationMath+1	No attempts yet	1s	128 MB	Judgeable
Mouse MoveThe cursor starts at (0,0) on a screen of width c and height r; each relative move is clamped to the screen edges, and the position after every move must be printed.	Easy2	SimulationImplementation+2	No attempts yet	1s	128 MB	Judgeable
SquaresGiven a number of tiles, find the largest integer side length whose square does not exceed that number.	Easy2	MathImplementation+1	No attempts yet	1s	128 MB	Judgeable
Terms of OfficePrint every year from X to Y in which all four offices change, which happens on multiples of lcm(4,2,3,5) = 60, formatted as a fixed sentence.	Easy2	MathImplementation+2	No attempts yet	1s	128 MB	Judgeable
Constrained PermutationsCount permutations of 1..n (n at most 9) that satisfy given ordering constraints x before y.	Easy2	Brute forceCombinatorics+2	No attempts yet	1s	128 MB	Judgeable
Fraction ActionReduce a numerator and denominator to simplest form, then print it as a whole number, a proper fraction, or a mixed number.	Easy2	MathNumber theory+1	No attempts yet	1s	128 MB	Judgeable
Mod InverseGiven x and m, find n with 0 < n < m such that x*n mod m equals 1, or report that none exists.	Easy2	Number theoryBrute force	No attempts yet	1s	128 MB	Judgeable
CalendarGiven the weekday of the 1st and the number of days, print a month calendar in a fixed weekly layout with right-aligned columns.	Easy2	ImplementationSimulation+1	No attempts yet	1s	128 MB	Judgeable
Cross-Number PuzzlePrint all perfect numbers from 1000 to 9999, then all three-digit numbers equal to the sum of their digits' cubes.	Easy2	Brute forceMath+1	No attempts yet	1s	128 MB	Judgeable
NumbersGiven three distinct digits and one of their six permutations, find that number's 1-based rank when all six permutations are sorted ascending.	Easy2	MathSorting+2	No attempts yet	1s	1024 MB	Judgeable
Building BlocksGiven a target height N and three block heights, pick the kind whose multiples get closest to N, breaking ties by smaller block then shorter tower.	Easy2	MathBrute force	No attempts yet	1s	1024 MB	Judgeable
EntropyRead one line of text, count how often each character appears, and print the Shannon entropy rounded to three decimals.	Easy2	Hash mapMath+2	No attempts yet	1s	128 MB	Judgeable
ExpressionGiven N, build a fully parenthesized NAND (Sheffer stroke) expression for the carry-out bit by iterating a fixed string concatenation rule.	Easy2	StringImplementation+2	No attempts yet	1s	128 MB	Judgeable
Right Triangle CheckFor each of n triples of side lengths, decide whether the triangle is right by checking if the largest side squared equals the sum of the other two squared.	Easy2	MathGeometry+2	No attempts yet	1s	128 MB	Judgeable
GaussFor each test case, compute the sum of all integers from n to m inclusive and print the test case number followed by the sum.	Easy2	MathImplementation	No attempts yet	1s	128 MB	Judgeable
StuPIdGiven an ID with one unknown digit, use the checksum rule to find the missing digit and print the corrected ID.	Easy2	MathImplementation+1	No attempts yet	3s	128 MB	Judgeable
Sexagenary Cycle (干支)Given a year, print its sexagenary cycle name as a branch letter A-L followed by a stem digit 0-9.	Easy2	MathImplementation	No attempts yet	1s	128 MB	Judgeable
CuboidsFor each cuboid row with one of the four values zeroed out, compute and print the missing length, width, height, or volume.	Easy2	MathImplementation	No attempts yet	1s	128 MB	Judgeable
DivisibilityGiven a base-62 string, decide whether the number it represents is divisible by 61.	Easy2	MathNumber theory+1	No attempts yet	1s	128 MB	Judgeable
TeleprimeGiven a six-digit number and a digit to prepend, print Yes if both the original and the resulting seven-digit number are prime.	Easy2	Number theoryMath+2	No attempts yet	1s	128 MB	Judgeable
ConcertRead 10 RGB triples per data set, average each channel, and print the average rounded to the nearest integer.	Easy2	MathImplementation	No attempts yet	1s	128 MB	Judgeable
Ways to Make RectanglesCount the number of unordered pairs (a, b) with a <= b and a*b <= n.	Easy2	MathBrute force+1	No attempts yet	1s	256 MB	Judgeable
PolynomialGiven a polynomial's coefficients and an integer x, print the last three digits of \|W(x)\|, padded with leading zeros.	Easy2	MathImplementation+1	No attempts yet	1s	128 MB	Judgeable
KamilGiven a word Kamil spoke, count the words he could have meant, since each position may map to one of several letters.	Easy2	MathCombinatorics+1	No attempts yet	1s	128 MB	Judgeable
JulkaGiven the total apples and how many more Klaudia has, compute each girl's count.	Easy2	MathImplementation	No attempts yet	1s	128 MB	Judgeable
Units Digit of a Power of TwoThe task is to print the units digit of 2 to the power n for a huge n.	Easy2	MathImplementation	No attempts yet	1s	128 MB	Judgeable
Caesar CipherDecode a Caesar-shifted uppercase message by matching its most frequent letter to the given original letter.	Easy2	StringArray+1	No attempts yet	1s	512 MB	Judgeable
Non-DivisorsGiven n, print the smallest and the largest integers from 1 to n that do not divide n.	Easy2	Number theoryMath	No attempts yet	1s	128 MB	Judgeable
Sums and DifferencesCount ordered pairs from distinct positions where the difference exceeds the sum, which holds exactly when the second element is negative.	Easy2	MathCombinatorics	No attempts yet	1s	128 MB	Judgeable
Step on the FootKozik and Adrian alternately shorten the gap by their foot lengths, and the first player facing a gap shorter than his foot wins.	Easy2	Math	No attempts yet	1s	128 MB	Judgeable
KwadratDecide whether four given points are the vertices of a non-degenerate square with sides parallel to the axes.	Easy2	GeometryImplementation	No attempts yet	1s	128 MB	Judgeable
Dividing the Chocolate BarTwo brothers split an a by b chocolate bar with one straight cut so the two pieces differ in area as little as possible.	Easy2	Math	No attempts yet	1s	128 MB	Judgeable
Overlapping Rectangle AreaGiven two axis-aligned rectangles, compute the area of their overlapping region.	Easy2	Geometry	No attempts yet	1s	128 MB	Judgeable
Little SnowmanChoose whether the fixed ball k is the bottom, middle, or top of a three-ball snowman with halved volumes to maximize total volume within x liters.	Easy2	MathBrute force	No attempts yet	1s	128 MB	Judgeable
Bouncing BallGiven drop height x and target w, find the smallest number of doublings that make x reach at least w.	Easy2	Math	No attempts yet	1s	512 MB	Judgeable
Making Grid PaperPick the sheet that yields the most grid cells under the margin and spacing rules, breaking ties by area, and output its area.	Easy2	MathImplementation	No attempts yet	1s	128 MB	Judgeable
PaintsCompute the extra red, yellow, and blue paint to buy after splitting each mixed room amount evenly between its two base colors.	Easy2	Math	No attempts yet	1s	128 MB	Judgeable
TournamentFor each test case with n contestants and group size k, count how many contestants can reach the final survivors under some grouping.	Easy2	Math	No attempts yet	1s	128 MB	Judgeable
Missing DigitsEach cipher hides one digit as x in A or B, and you try digits 0 to 9 to find the smallest that makes A divisible by B.	Easy2	Brute forceMath	No attempts yet	1s	128 MB	Judgeable
Closing the CircuitShift every given upper pair forward by one position modulo n and print the sorted lower pairs after TAK.	Easy2	ImplementationSorting+1	No attempts yet	3s	128 MB	Judgeable
MondaysGiven year length N, week length M, and starting weekday L, count the days from 1 to N that fall on the first weekday.	Easy2	Math	No attempts yet	1s	128 MB	Judgeable
Rock Paper ScissorsCompare the two players' winning chances from their move probabilities and print who is more likely to win each match.	Easy2	ProbabilityMath+1	No attempts yet	1s	128 MB	Judgeable
BookmakersDecide whether stakes on both match outcomes can guarantee a profit given decimal odds X and Y.	Easy2	Math	No attempts yet	1s	128 MB	Judgeable
Power StripsGiven N cords and strips that add K outlets each, compute how many free outlets remain after connecting everything.	Easy2	Math	No attempts yet	1s	128 MB	Judgeable
Changing a Light BulbCompute the sum 1 + 4 + ... + 4^(A-1) modulo 500000009 for the given level count A.	Easy2	Math	No attempts yet	1s	128 MB	Judgeable
Old BillGiven N and middle digits XYZ, fill in the first and last digits of the five-digit total so N divides it, choosing the largest valid total.	Easy2	Brute forceMath	No attempts yet	1s	128 MB	Judgeable
ClockFind the time with the median clock-hand angle among five given times, breaking angle ties by earlier time.	Easy2	MathSorting+1	No attempts yet	1s	128 MB	Judgeable
Mathematical CuriosityCount pairs 0<a<b<n where a squared plus b squared plus m is divisible by a times b.	Easy2	Brute forceMath	No attempts yet	1s	128 MB	Judgeable
Addition in Different BasesAdd two numbers of up to 1000 digits in bases 1 to 35, including unary base 1, and print each equation with its sum in the same base.	Easy2	ImplementationString+1	No attempts yet	1s	128 MB	Judgeable
Air speed of a fully laden swallowYou group messy swallow flight records by subspecies and compute two average speeds for each group.	Easy2	ImplementationString+1	No attempts yet	1s	128 MB	Judgeable
Sir Bedavere's Bogus DivisionPrint every three-digit fraction with numerator in L to R that keeps its value after erasing the shared digit.	Easy2	Brute forceMath	No attempts yet	1s	128 MB	Judgeable
Taunt Exposure EstimationRead CSV time measurements and estimate total exposure with the trapezoid rule, then print the range and integral with fixed rounding.	Easy2	ImplementationMath	No attempts yet	1s	128 MB	Judgeable
Consecutive Digits in a Rational NumberReport the base-7 digits in positions f through l after the point for the fraction n over d.	Easy2	SimulationMath	No attempts yet	1s	128 MB	Judgeable
Check DigitsRead numbers until a # line and print each with its mod-11 weighted check digit or Rejected.	Easy2	ImplementationMath	No attempts yet	1s	128 MB	Judgeable
Reducing Improper FractionsRewrite each given fraction as a mixed number, omitting the zero integer or fractional part.	Easy2	Math	No attempts yet	1s	128 MB	Judgeable
Geometric InflationSimulate the monthly price recurrence with half-up cent rounding and print the Nth month cost with comma grouping.	Easy2	SimulationMath+1	No attempts yet	1s	128 MB	Judgeable
Arithmetic and Geometric SumsGiven N and the first three terms of an arithmetic or geometric series, detect the type and output the sum of the first N terms for each data set.	Easy2	MathImplementation	No attempts yet	1s	128 MB	Judgeable
Monitor DPICompute horizontal and vertical DPI from diagonal size and resolution with the 16:9 ratio for each line until 0 0 0.	Easy2	MathImplementation	No attempts yet	1s	128 MB	Judgeable
Fast Food PrizesAdd up, over disjoint prize sets, the prize value times the smallest sticker count among its required kinds.	Easy2	GreedyMath+1	No attempts yet	2s	128 MB	Judgeable
Zombie InvasionProcess villages east to west, moving half of each village west and leaving at most one behind, with everything gathering on the west coast.	Easy2	SimulationMath	No attempts yet	2s	128 MB	Judgeable
Von NeumannTwo trains approach each other while a fly shuttles between them, and the program prints how far the fly travels before they collide.	Easy2	Math	No attempts yet	1s	128 MB	Judgeable
The n Days of ChristmasFor each n until 0, compute the total gifts when day k of n brings k gifts down to 1.	Easy2	MathImplementation	No attempts yet	2s	128 MB	Judgeable
Long is a train, a train is fast, fast is a planeCompute the travel time gap between a slower train and a faster plane over M km and print each gap as rounded H:MM:SS.	Easy2	ImplementationMath	No attempts yet	1s	128 MB	Judgeable
Perfect Number CheckDecide whether each given integer equals the sum of its proper divisors and print the equation or a negative verdict.	Easy2	Number theoryImplementation	No attempts yet	2s	128 MB	Judgeable
Kids love candyEach test case gives candy piles and K, and asks for the most children who can each receive at least K pieces of a single kind.	Easy2	MathGreedy	No attempts yet	1s	128 MB	Judgeable
Combination LockCount distinct triples of dial positions within circular distance 2 of either of two given combinations.	Easy2	Brute forceMath	No attempts yet	1s	128 MB	Judgeable
VicinityFor each query, count how many of the n points lie within distance d_v of the chosen base point, excluding the base point itself.	Easy2	Brute forceGeometry	No attempts yet	1s	128 MB	Judgeable
Stone Game 5Two players alternately take 1 or 3 stones from a pile of N, and the program prints SK or CY for optimal play.	Easy2	Game theoryMath	No attempts yet	1s	128 MB	Judgeable
Anti-Arithmetic PermutationFor each permutation of 0 to n-1, decide whether any three terms in order form an arithmetic progression.	Easy2	Brute forceMath	No attempts yet	1s	128 MB	Judgeable
Fibonacci remainderFor each test case, compute the P-th Fibonacci number of the sequence starting 1, 1 modulo Q and print it as Case #x: M.	Easy2	MathSimulation	No attempts yet	1s	128 MB	Judgeable
Qurban 2011Given buffalo part orders and sheep orders, round buffalo parts up by seven and pack the animals into trips of three buffaloes or six sheep.	Easy2	MathImplementation	No attempts yet	1s	128 MB	Judgeable
BeeThe program counts logged jobs under each of seven bee work codes and prints each count with its share of the total.	Easy2	ImplementationArray+1	No attempts yet	1s	128 MB	Judgeable
Extending Goldbach's ConjectureThe program reads each m and prints whether m consecutive odd integers sum to m cubed and the first one when they do.	Easy2	Math	No attempts yet	1s	128 MB	Judgeable
The KingPick any subset of up to 100 values from minus 3 to 3 so the sum of the chosen values raised to the given power 1 to 3 is as large as possible.	Easy2	GreedyMath	No attempts yet	2s	128 MB	Judgeable
Rectangle intersectionCompute the area shared by all n axis-aligned rectangles, or 0 when they do not all overlap.	Easy2	GeometryIntervals	No attempts yet	2s	512 MB	Judgeable
EuclidRead two positive integers up to 32767 and print their greatest common divisor.	Easy2	Number theory	No attempts yet	2s	512 MB	Judgeable
Zeros in a FactorialCount how many zero digits appear in the decimal representation of n factorial for a given n below 100.	Easy2	MathImplementation	No attempts yet	1s	128 MB	Judgeable
The Euclidean AlgorithmCount how many subtraction steps the original Euclidean algorithm needs to find the gcd of two integers up to 32767.	Easy2	SimulationMath	No attempts yet	1s	128 MB	Judgeable
Centroid of Point MassesCompute the mass-weighted average x and y over each point set and print each centroid rounded to two decimals.	Easy2	MathImplementation	No attempts yet	3s	128 MB	Judgeable
Polar ExplorerGiven planet radius, fuel, and the angle to the crash site, decide if the round trip on the shorter arc fits and report leftover fuel or reachable miles.	Easy2	MathImplementation	No attempts yet	1s	128 MB	Judgeable
Microwave ButtonsPress the 5-minute, 1-minute, and 10-second buttons to total exactly T seconds with the fewest presses, or print -1 when impossible.	Easy2	GreedyMath	No attempts yet	1s	64 MB	Judgeable
Focal Length of a LensGiven object and image distances for each test case, compute the lens focal length and print it rounded to one decimal place.	Easy2	MathImplementation	No attempts yet	1s	256 MB	Judgeable
Aligned CalendarConvert each Gregorian date into the 13-month calendar with 28-day months and report the leftover days as holidays.	Easy2	MathImplementation	No attempts yet	1s	256 MB	Judgeable
Tax Rate ChangedFind the pair of pre-tax prices that summed to s after x% tax and gives the largest total after y% tax.	Easy2	Brute forceMath	No attempts yet	1s	256 MB	Judgeable
Dice GameEach player rolls two dice with consecutive face ranges and the larger total wins, so compute both win probabilities from the four ranges.	Easy2	ProbabilityBrute force	No attempts yet	1s	256 MB	Judgeable
Runway PlanningGiven each heading in degrees, compute the two-digit runway number by rounding and folding to the range 1 to 18.	Easy2	MathImplementation	No attempts yet	1s	256 MB	Judgeable
Ice Bucket ChallengeFind the fewest ice-pouring participants needed to reach a donation goal when each pourer donates 10 and recruits K friends while skippers donate 100.	Easy2	Math	No attempts yet	1s	256 MB	Judgeable
HeadshotAfter a click on a circular cylinder, compare firing at once against spinning first and print which choice is safer.	Easy2	ProbabilityString	No attempts yet	1s	64 MB	Judgeable
Radix 32 ConversionConvert each base-32 string of up to 8 digits to its decimal value and to binary by expanding every digit to 5 bits.	Easy2	MathString	No attempts yet	1s	64 MB	Judgeable
Growling GearsFor each gear compute the vertex value of -aR^2 + bR + c and output the gear with the largest maximum.	Easy2	Math	No attempts yet	1s	256 MB	Judgeable
TriplesCount triples x<=y<=z<=m with x^j+y^j=z^j for each exponent j from 2 to n and print the total.	Easy2	Brute forceMath	No attempts yet	5s	256 MB	Judgeable
Joy of FlightAdd up the wind drift over k seconds and, if the remaining distance fits the speed limit, print the evenly paced flight positions.	Easy2	ImplementationSimulation+1	No attempts yet	2s	256 MB	Judgeable