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Next Friday the 13th

What is the shortest program that can predict the next time Friday will fall on the 13th day of the month? Must be an complete functioning program (not just a function/subroutine) Must print out date ...
898 views

Dissociated Press

http://en.wikipedia.org/wiki/Dissociated_press Dissociated Press is an algorithm that generates random text from an existing text. The algorithm starts by printing any N consecutive words (or ...
217 views

Directories required for creating a folder tree

Say that you have this folder structure on your coumputer: /a And you want to have these folders: /a/b /a/c /b/b You would ...
1k views

Random dice tipping

In a standard dice (die) the numbers are arranged so that opposite faces add to seven. Write the shortest possible program in your preferred language which outputs a random throw followed by 9 random ...
907 views

Print Triangle Wave of Numbers

Given the amplitude and period for a wave, print the wave. See sample output for more details. The total number of wave forms equals the period, and the height of each wave equals the amplitude. ...
366 views

Count even steps of 196 algorithm

In the 196-algorithm one starts from an integer and then adds its reverse to it until a palindrome is reached, like this: ...
1k views

How many switches are ON

A class has N student and the class room has N switches (all turned OFF and numbered 1 to N). Each student has an enrollment number assigned from 1 to N. Each student serially (by number) toggles the ...
451 views

Physics golf: inclined shooting

"And now for something, completely different." An angry bird is shot at an angle β to the horizontal at a speed u. The ground is steep, inclined at an angle α. Find the horizontal distance q that the ...
4k views

Carmichael Numbers

EDIT: I am changing the challenge. Write a program to print Carmichael numbers. The challenge is to print the maximum number of them in less than 5 secs. The numbers should be in increasing order. ...
3k views

Square free Numbers

Given a number N, write the shortest complete program to find the number of square-free integers below N. Sample Input 100000 Sample Output 60794 Constraints: ...
930 views

Crossword grid verification

Validate a proposed crossword grid. Entries should be full programs that simply test a proposed grid to determine if it meets a set of conditions for making crossword solvers happy. Input The input ...
887 views

Comparing powers.

Compare two numbers N1 = abc, N2 = def by constructing a function f(a,b,c,d,e,f) that: returns 1 if N1 > N2 returns -1 if N1 < N2 Note: You are not required to return any value for any other ...
279 views

Power modulo golf. [closed]

Write a function f(a,b,c) that calculates a^b (mod c) in less than 10 seconds. a, b < 10^100 c < 10000. examples: ...
861 views

Modulo code golf

Write a function f(a,b) that returns a mod b given the constraints: you can't use division in any way ...
918 views

Finding “sub-palindromes” 2: subsequences.

The same task as Finding "sub-palindromes" but instead of finding substrings you must find subsequences that are not substrings. eg1: ...
5k views

Print a Binary Tree

Inspired by a recent question on SO... Write a function to print a binary tree in the following format: 3 / \ 1 5 \ / \ 2 4 6 The output should ...
654 views

Implement BCD Arithmetic

Write the shortest function you can that takes two binary-coded decimal integers and a character indicating an arithmetic operation to perform and return the result. Input Specification You will be ...
2k views

Polynomial Long Division

Implement polynomial long division, an algorithm that divides two polynomials and gets the quotient and remainder: (12x^3 - 5x^2 + 3x - 1) / (x^2 - 5) = 12x - 5 R 63x - 26 In your programs, you will ...
977 views

Another problem from our internal golfing...this one around the holidays last year. PROBLEM Andy, Barb, Carl, Didi, Earl, and Fran are buying gifts for each other. Draw names for a gift exchange. ...
671 views

How many squares are guarded by chess queens?

Today marks the 15th anniversary of Garry Kasparov's defeat against Deep Blue. Speaking of chess... Input is a string that represents an 8x8 chess board containing only empty squares (...
4k views

Fair outcome using unfair coin [closed]

I have been thinking a lot about the following puzzle, but could not arrive at a solution. Can someone explain to me how can you get a fair (equal probability) outcome using only an unfair coin (...
3k views

Partition of a positive integer N [closed]

Find the number of partitions of a positive integer n. Hope someone uses the explicit finite formula for the partition function defined in Jan Hendrik Brunier and Ken Ono paper here. ...
1k views

Random Sentence Generator

Write the shortest program you can in any language that reads a context-free grammar from and the number of sentences to produce from stdin, and generates that many ...
506 views

Is this figure connected?

You are given a list of (x,y) grid coordinates. Your function should decide whether the figure obtained by coloring in the squares of the grid with the given ...
3k views

Roman numeral converter function

Create the shortest function to convert a string of Roman numerals to an integer. The rules for each letter can be found at the Wikipedia page. Letters above 1,000 will have parentheses placed ...
7k views

Print NxN spiral of ascending numbers [closed]

The numbers should be printed with leading zeroes in a field with length = (number of digits of N^2). Input (N): 4 Output: ...
661 views

Finish a symmetrical map

You are given one-quarter of a map that is symmetrical over the x- and y-axes as input. The program should print the complete map. The map can contain the following characters: ...
3k views

Calculate the last digits of Graham's Number

Graham's number ends in a 7. It is a massive number, in theory requiring more information to store than the size of the universe itself. However it is possible to calculate the last few digits of ...
1k views

Sum of integers in string, separated by non-numericals such as 'a' and 'Y'

Create a program which sums all integers found in a string which is set as a variable in the program (thus, the program doesn't have to handle any input). The integer numbers are separated by non-...
978 views

Calculate the number of trailing zeros in n! [duplicate]

Write a function which takes n as a parameter, and returns the number of trailing zeros in n!. Input Constraints 0 <= n <= 10^100 Output Constraints Should be return the result in less than ...
5k views

Binary representation of a number is palindrome or not?

Write a full program to find whether the binary representation of a number is palindrome or not? Sample Input 5 Sample Output YES Print ...
1k views

->The Tragedy of Macbeth<- [closed]

The Setup Here you can find the full text of The Tragedy of Macbeth. If you view the source, and save it as text, you will notice it comes out to 206,244 total characters (including the whitespace ...
4k views

Last non-zero digit of n!

Given an integer 1 ≤ N ≤ 1,000,000 as input, output the last non-zero digit of N!, where ! is the factorial (the product of all numbers from 1 to N, inclusive). This is OEIS sequence A008904. Your ...
867 views

Word Spinner Puzzle

This is a word puzzle. Your program should accept two words on the standard input. Word one is the start word. Word two is the end word. From the start word you have to reach the end word changing/...
888 views

How much snow did you get?

My apologies for the wordiness. We had fun with it at work in our internal golfing, but it required a few emails for clarification, so I hope I captured most of that the first time. PROBLEM Given a “...
4k views

Decipher a Vigenère ciphertext

The Vigenère cipher was a simple polyalphabetic cipher that basically applied one of several Caesar ciphers, according to a key. Bascially the letters in the key indicate which shifted alphabet to use....
1k views

Find prime factors [duplicate]

A whole program to find the prime factors of a given number. The number will be given on standard input.
3k views

Multiply without multiply [closed]

Write the fastest (best big-O) and smallest multiplication algorithm for positive integers, without using multiplication operators. You are only allowed addition, subtraction, logical functions (AND, ...
576 views

1k views

Tree traversal: Depth-first search

Write the shortest code that traverses a tree, depth-first. Input Any programmatical structure found in your language of choice: lists, tuples, queues etc. Output A list of "names" of the nodes in ...
4k views

Robot Finds Kitten

The challenge The shortest code by character count to help Robot find kitten in the fewest steps possible. Golfers, this is a time of crisis - Kitten gone missing and it's Robot's job to find it! ...
4k views

Self-Interpreting Interpreter

Based on a comment by George Edison to this question, write the smallest self-interpreting interpreter. You may use the language of your choosing. Empty languages do not count. Your program must be ...