# All Questions

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### Forecast the weather

Write the shortest program to forecast the weather for the next 7 days The input (from stdin) is the weekday and the season The output (to stdout) is seven lines weekday and the temperature in ...
• 15.1k
3k views

### Implement Bogosort

Is solving Sudoku too hard? Even the brute force version? Here's a coding exercise that's a little easier. I hope. :-P Write the shortest function to implement bogosort. In specific, your function ...
• 4,917
5k views

### Implement a Brute Force Sudoku Solver

Implement the shortest Sudoku solver using guessing. Since I have received a few request I have added this as an alternative question for those wishing to implement a brute force sudoku solver. ...
• 717
2k views

### Build an engine for a maze game

This is a follow up of Print a maze question. If you like this question, please add more maze generation algorithms ;). For this task you'll have to implement a game engine for one player who must ...
• 6,066
2k views

### IPv4 Integer Conversion Function

Write the shortest function to convert an IP address into it's integer representation and output it as an integer. To change an IPv4 address to it's integer representation, the following calculation ...
• 301
35k views

### Tips for golfing in Ruby

What general tips can you give for golfing in Ruby? I'm looking for ideas that can be applied to code golf problems in general that are specific to Ruby. (For example, "Remove comments" would not be ...
• 1,257
3k views

### Implement a Non-Guessing Sudoku Solver

Implement the shortest Sudoku solver. Sudoku Puzzle: ...
• 717
7k views

### Calculate ISBN-13 check digit

Write a function which, given the first 12 digits of an ISBN-13 code, will calculate the entire ISBN via calculating and appending an appropriate check digit. Your function's input is a string ...
• 6,442
6k views

### Binary tree encoding [closed]

Let's suppose you have a complete binary tree (i.e. each internal node has exactly two non empty descendants). Each node contains a nonzero integer. You are given the task of encoding and decoding the ...
• 6,066
580 views

### Binary search ("bisect") tool

Implement the binary search algorithm as used to identify the source code revision that breaks a computer software program. Your tool should take two arguments specifying the earliest and latest ...
• 5,577
3k views

### Crossword numbering

Produce a program to correctly number a crossword grid. Input The input will be the name of a file representing the crossword grid. The input filename may be passed as an argument, on the standard ...
44k views

### Obfuscated Hello World

Create the shortest possible obfuscated program that displays the text "Hello World". In order to be considered an obfuscated program, it must meet at least two of the following requirements: Does ...
• 6,442
908 views

### Project Euler Problem 12: optimize memory usage

I am referring to Project Euler #12. Write the solution in any language you want, but consume the least amount of memory while executing. Running time is not measure in this case. The sequence of ...
• 283
809 views

### Quine that takes as input the name of a language and outputs the same thing implemented in the input language

From Quine central: Write a quine that takes as input the name of a language and outputs the same thing implemented in the input language. The source article has something you can work from, but as ...
• 12.5k
6k views

### Shortest Floor Function

Your task is to implement a floor function in as few bytes as possible. A floor function is a function that takes a real number and returns the largest integer less than or equal to the input. Your ...
16k views

### Write an interpreter for the untyped lambda calculus

The challenge is to write an interpreter for the untyped lambda calculus in as few characters as possible. We define the untyped lambda calculus as follows: Syntax There are the following three ...
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13k views

• 5,577
2k views

### Nokia mystery puzzle [closed]

A friend sent me this puzzle. I'm pretty sure solving it will require some programming. Can anyone crack it? The original is here in case of encoding issues in the past below. ...
• 12.5k
5k views

### Decryption by pattern analysis

You are given an encrypted string, encrypted using a very simple substitution cipher. Problem You do not know what the cipher is but you do know the ciphertext is English and that the most frequent ...
• 3,318
9k views

### Print 1 to 1000 in C++ without semi-colons

Following this popular question, present your solution which prints the numbers 1 to 1000 (all of them, not the string "1 to 1000" verbatim or something funny) in C++ without using any semi-colons. ...
• 12.5k
5k views

### Print a random maze

Write a program that generates and prints a random maze using the algorithm of your choice. The maze should be different for multiple runs of the program. Height and width are given as command line ...
• 6,066
11k views

### Reverse stdin and place on stdout

Requirements: Take an input on stdin including new lines / carriage returns of unlimited length (only bounded by system memory; that is, there is no inherent limit in the program.) Output the reverse ...
• 3,318
10k views

### Reverse Polish notation

You must evaluate a string written in Reverse Polish notation and output the result. The program must accept an input and return the output. For programming languages that do not have functions to ...
880 views

### Compute modular inverse

Given two positive numbers $x$ and $n$ with $x<2^n$, write the shortest possible function to compute $x^{-1} \mod 2^n$. In other words, find $y$ such that $xy=1 \mod 2^n$. Your ...
• 20.8k
1k views

### Slot Machine Hacker

Problem: Slot Machine Hacker from Facebook Hacker Cup 2011 Round 1B Goal: Shortest code in your favourite language using stdin/stdout. You cannot assume ...
• 12.5k
1k views

### Freely available books for code golfing? [closed]

Can you recommend any freely available books about code golfing in general and especially in Java and C++?
7k views

### Tips for golfing in PowerShell

What general tips do you have for golfing in Windows PowerShell? I'm looking for ideas that can be applied to code golf problems in general that are at least somewhat specific to PowerShell (e.g. "...
• 12.9k
24k views

### Drawing a cube in ASCII art

Task description: Draw a cube in ASCII art in roughly a cabinet projection. Monospaced fonts often have characters that are about twice as high as they are wide. ...
• 12.9k
3k views

### Print largest integer you can with the fewest characters [closed]

Find a way to output a large integer with few characters. Solutions will be scored based on the magnitude of the number and shortness of code. EDIT: Let's impose a time limit of a minute on sensible ...
• 12.5k
3k views

### Finding "sub-palindromes".

The shortest code that finds all unique "sub-palindromes" of a string, that is: any substring with length > 1 that is a palindrome. eg.1 ...
• 5,452
20k views

### Tips for code-golfing in C#

What general tips do you have for golfing in C#? I'm looking for ideas that can be applied to code golf problems in general that are at least somewhat specific to C# (e.g. "remove comments" is not an ...
• 1,863
4k views

### 196 algorithm code golf

Write a short program for 196-algorithm. The algorithm starts from an integer, then adds its reverse to it until a palindrome is reached. e.g. ...
• 5,452
1k views

### Shortest path in a graph

Write a program to take a graph (from either standard input or a file, your choice) and find a shortest path in the graph. Graphs are specified using the following format: ...
• 20.8k
431 views

### Compress programs

Write a program/script that decompresses and passes any compressed data appended at the end of the binary/file as standard input to a program specified as arguments. ...
• 6,066
732 views

### Write a compressing util for gzip files

The task of this challenge is as following: Write a program that reads a file of reasonable size (let's say <16 MB) from stdin or anywhere else (however you like, but must not be hardcoded), and ...
• 10.1k
19k views

### Tips for golfing in C++

What general tips do you have for golfing in C++? I'm looking for ideas that can be applied to code golf problems in general that are at least somewhat specific to C++ (e.g. "remove comments" is not ...
• 12.5k
33k views

### Morse code translator

Write the shortest program to transform the standard input into Morse code. Characters not in the table should be printed as they are.
• 6,066
5k views

### Poisson random number generator [closed]

What is the shortest function (implemented in C) that will return a random draw from a Poisson distribution (given the mean or λ parameter)? ...
3k views

### Test if a given number is a Vampire Number [duplicate]

EDIT: In the interest of increasing the complexity, i've added more to the challenge. In mathematics, a vampire number (or true vampire number) is a composite natural number v, with an even ...
• 2,208
935 views

### Tree traversal. [closed]

Write the shortest code that traverses a tree, breadth-first. Input any way you like Output a list of "names" of the nodes in correct order.
• 5,452
5k views

### Sum of primes between given range

Write the shortest code for finding the sum of primes between $a$ and $b$ (inclusive). Input $a$ and $b$ can be taken from command line or stdin (space seperated) Assume \\$1 \le a \le b \le ...
• 2,208
266 views

### Sharing Inherited Land [closed]

You and your brother have inherited a rectanglar block of land. This block of land's corners are read in from stdio as TLX,TLY,TRX,TRY,BLX,BLY,BRX,BRY (all decimal ...
• 1,007
17k views

### Obfuscated FizzBuzz Golf [closed]

Create the shortest possible obfuscated FizzBuzz implementation. To be considered obfuscated, it should satisfy at least one of the following: Does not contain any of the words "Fizz", "Buzz", or "...
• 1,199
42k views

### Fibonacci function or sequence

The Fibonacci sequence is a sequence of numbers, where every number in the sequence is the sum of the two numbers preceding it. The first two numbers in the sequence are both 1. Here are the first ...
• 4,917
25k views

### Interpret brainfuck

Write the shortest program in your favourite language to interpret a brainfuck program. The program is read from a file. Input and output are standard input and standard output. Cell size: 8bit ...
• 6,066
4k views

### Reimplementing square root [duplicate]

Define a function, s, which takes a number and returns the square root. No use of library functions, such as Java's Math.sqrt() or PHP's built in sqrt(), allowed.
• 1,145
63k views

### Golf you a quine for great good!

Using your language of choice, golf a quine. A quine is a non-empty computer program which takes no input and produces a copy of its own source code as its only output. No cheating -- that means ...
• 2,697
139k views

### Tips for golfing in Python

What general tips do you have for golfing in Python? I'm looking for ideas which can be applied to code-golf problems and which are also at least somewhat specific to Python (e.g. "remove comments" is ...
• 12.5k
765 views

### Fast Topswops calculation [closed]

From AZSPCS: Suppose you have a deck containing n cards. Each card contains a number from 1 to n, and each number appears on exactly one card. You look at the number on the top card -- let's says it'...
• 6,066