Questions tagged [code-golf]

Code-golf is a competition to solve a particular problem in the fewest bytes of source code.

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3
votes
3answers
974 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: ...
19
votes
5answers
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 ...
4
votes
3answers
687 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 ...
15
votes
5answers
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 ...
11
votes
15answers
1k views

Holiday Gift Exchange

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. ...
6
votes
7answers
683 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 (...
8
votes
1answer
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 ...
8
votes
8answers
517 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 ...
16
votes
4answers
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 ...
12
votes
14answers
686 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: ...
14
votes
6answers
4k 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 ...
17
votes
33answers
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-...
6
votes
5answers
997 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 ...
18
votes
30answers
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 ...
23
votes
17answers
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 ...
10
votes
4answers
883 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/...
12
votes
7answers
899 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 “...
29
votes
17answers
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....
10
votes
18answers
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.
8
votes
17answers
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, ...
10
votes
6answers
588 views

Work out change [closed]

You are writing a program for an automatic cash register. The user needs change with the least number of coins used. Write a program which takes an amount (say $1.53) and gives change in US ...
7
votes
9answers
408 views

All Possible Matching Lists

Implement a function that takes a list that consists of 0, 1 or 2, the list is called "pattern". Your job is to return all possible lists that match the pattern. 0 matches 0 1 matches 1 2 matches 0 ...
6
votes
3answers
639 views

Word guessing game

A program should take an input on stdin, and guess what a word might be. It should run as a session. One example session is shown below. Characters are fed to it, with a * for a letter not revealed; ...
14
votes
5answers
2k views

Interpret Befunge-93

The program will be provided as the first argument, stdin should be used for all read requests by the program and stdout for all write requests. It can be assumed that the program is less than 80 ...
10
votes
18answers
752 views

Output nearby primes

Write a program which takes an input (which may or may not be prime), and lists the immediate prime following and preceding it. Example input: 1259 Example ...
29
votes
5answers
2k views

Advanced Calculator

You must write a program that evaluates a string that would be entered into an advanced calculator. The program must accept input using stdin and output the correct answer. For languages that do no ...
80
votes
189answers
17k views

Find the Factorial!

Create the shortest program or function that finds the factorial of a non-negative integer. The factorial, represented with ! is defined as such $$n!:=\begin{...
4
votes
5answers
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 ...
51
votes
7answers
5k 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! ...
27
votes
8answers
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 ...
23
votes
12answers
5k views

Assembly Language Quine

Write the shortest possible assembly-language quine. Use any ISA you want, unless it has a print-quine instruction or equivalent. Examples include x86, MIPS, ...
20
votes
19answers
4k views

Basic Calculator

You must write a program to evaluate a string that would be entered into a calculator. The program must accept input and output the correct answer. For languages that do not have standard input/...
13
votes
5answers
605 views

Perfect powers in more than one way?

Challenge Your task is to write a program or function which, given a positive integer \$N\$, finds all positive integers less than or equal to \$N\$ that can be expressed as a perfect power in more ...
18
votes
5answers
1k views

Fix a broken random function

A friend has an add-on card in their computer which generates a perfectly random number from 1 to 5 inclusive. Unfortunately, they spilt cola on it somehow, and it now generates only 2's for all ...
14
votes
16answers
644 views

Integer to string with given radix

Write the shortest function to convert an integer into a numeric representation given a radix between 2 and 62. e.g.: to_string(351837066319, 31) => "codegolf"
5
votes
6answers
419 views

Minimum of last k

Write a function that takes two arguments: a number k and a list l, and that returns another list ...
31
votes
16answers
4k views

Calculate 500 digits of pi

Write a program to calculate the first 500 digits of pi, meeting the rules below: It must be less than 500 characters in length. It cannot include "pi", "math.pi" or similar pi constants, nor may it ...
7
votes
0answers
771 views

Stable positive/negative separation [closed]

From SO. You are given an array with positive and negative integers. Write a function to change the elements order in the array such that negative integers are at the beginning, the positive integers ...
6
votes
11answers
588 views

Find the largest value of power.

Some numbers can be represented as perfect powers of other numbers. A number x can be represented as x = base^power for some integer base and power. Given an integer x you have to find the largest ...
9
votes
10answers
647 views

Find the number of x-digit numbers whose product of digits is N

Given two numbers \$N\$ and \$x\$, find the number of \$x\$-digit numbers whose product of digits is \$N\$ \$N <10^6\$ and \$x <12\$ ...
15
votes
28answers
3k views

Implement division

Implement a division algorithm in your favourite language which handles integer division. It need only handle positive numbers - but bonus points if it handles negative and mixed-sign division, too. ...
8
votes
8answers
432 views

Remainder When N divided by 2^M

Write the shortest code to find the remainder when an input number N is divided by 2^M. You cannot use /,* and % operator. ...
24
votes
19answers
2k views

Chris Pine's “Deaf Grandma”

I'm a mentor at RubyLearning and one of the exercises we give to our students is the "Deaf Grandma" exercise from Chris Pine's book "Learn to Program". Here's the description: Write a Deaf Grandma ...
13
votes
3answers
4k views

Write a JSON validator

Write a program that determines whether its input is valid JSON. Input: ASCII text: [\x00-\x7F]* Note: if ASCII is problematic, feel free to use another encoding, ...
37
votes
8answers
4k views

Self-compiling compiler [closed]

This is based on a talk on compilers I listened to a while back, but I, unfortunately, can't remember when or where. Create the shortest compiler in any language that can compile itself. Target any ...
15
votes
12answers
1k views

Implement glob Matcher

Implement a function of pattern and string to be matched, return true if the pattern matches the WHOLE string, otherwise false. Our glob pattern syntax is: ? ...
16
votes
4answers
28k views

Shortest URL regex match in JavaScript [closed]

Create the shortest regular expression that will roughly match a URL in text when run in JavaScript Example: ...
11
votes
7answers
1k views

Build a nine-level word guessing game

The basics: You'll need to provide a nine-level word guessing game in the fewest characters possible (in your language of choice). The metrics: Provide a word-list (one word per line, seperated by a ...
40
votes
12answers
7k views

Drawing a gradient in ASCII art

Task description: Write a program as short as possible to draw a radial gradient in ASCII art. The size of the output grid is predefined. The center point and the characters to be used for the ...
14
votes
8answers
778 views

Calculating areas.

The smallest code that gives the area between the curve p(x) = a0 + a1*x + a2*x2 + ..., the line y = 0, the line x = 0 and the line x = C (i.e. something like this: ) You can assume that p(x) >= 0 ...