Questions tagged [code-challenge]

A code challenge is a competition for creative ways to solve a programming puzzle with an objective winning criterion not covered by other scoring tags (e.g. code-golf).

750 questions
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Output the ŋarâþ crîþ alphabet song without using (m)any letters

Your goal is to write a program that takes no input and outputs the following text: ...
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Can a neural network recognize primes?

Background Recognizing primality seems like a poor fit for (artificial) neural networks. However, the universal approximation theorem states that neural networks can approximate any continuous ...
6k views

Source code ecological footprint

You've just been hired by a German car manufacturing company. Your first task, as an engineer, is to write a program that computes the ecological footprint of ASCII strings. The ecological footprint ...
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Source permutation

A permutation of a set $S = \{s_1, s_2, \dotsc, s_n\}$ is a bijective function $\pi: S \to S$. For example, if $S = \{1,2,3,4\}$ then the function $\pi: x \mapsto 1 + (x + 1 \mod 4)$ is a ...
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Largest number in ten bytes of code

Your goal is to print (to the standard output) the largest number possible, using just ten characters of code. You may use any features of your language, except built-in exponentiation functions. ...
11k views

What are the five most powerful characters in your language?

Choose any five characters your language supports. There are 5! = 5×4×3×2×1 = 120 ways these can be arranged into a 5-character string that contains each character once; 120 ...
5k views

“As we travel the universe…”

You'll be given the name of one of the 20 biggest objects in the Solar System. Your task is to return an approximation of its radius, expressed in kilometers. This is a code-challenge where your ...
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Output the Missing Character [duplicate]

When writing a programm 1 missing character can ruin everything, wouldn't it be great if the programm told you what was missing ? Task: Create any (non Empty) programm, that takes no input and ...
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Write a Quine Suite

We've had a lot of quine challenges, but a lot of the quine formats are similar, lets create some variance in our quines. Your task is to create a selection of programs in the same language (at least ...
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Find an Illegal String

The challenge is to find a string of characters that cannot appear in any legal program in your programming language of choice. That includes comments, strings, or other "non-executable" parts. ...
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Find efficient seating arrangement in a line [closed]

We have X Girls and Y Boys in a class. If more girls sit together they will not behave. Similarly if more boys sit together they will not behave. Write a program/algorithm to get maximum same gender ...
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Generate the longest error message in C++

Write a short program, that would generate the longest possible error message, in a standard C++ compiler (gcc, cl.exe, ...
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The Strange Unsorting Machine for Nefarious Purposes

Good Evening Golfers! Your challenge is to completely unsort a series of numbers. Input Exactly 100 integers will be fed to your program. Your program may accept the input either as a file, or via ...
739 views

Words hidden in my phone number [closed]

Telephones in the United States (and perhaps some other places) have letters associated with some of the numbers. ...
402 views

The greedy regex (robbers)

This is the robbers' post. The cops' is here. Your challenge is to take a cop's post and find an input that the regex matches but the program returns a falsey value. Once you have cracked a cop's ...
429 views

ASCII Maze Compression

Challenge Design a compression algorithm specialized for compressing ASCII mazes. You will need to create both a compression algorithm and a decompression algorithm. Your score will be based on the ...
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Make a long type signature

Challenge Find an expression, at most 100 bytes long, with the longest type signature. Rules Any statically typed language with type inference is allowed The type must be non-ambiguous, but ...
13k views

Fewest (distinct) characters for Turing Completeness

Summary: For any given language, what is the smallest amount of unique characters for your language to be Turing-Complete? Challenge: For any language of your choice, find the smallest subset of ...
36k views

Write Moby Dick, approximately

Here is a 1.2Mb ASCII text file containing the text of Herman Melville's Moby-Dick; or, The Whale. Your task is to write a program or function (or class, etc. -- see below) which will be given this ...
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A “Sorting” algorithm

There is a "sorting algorithm" sometimes called Stalin sort in which in order to sort a list you simply remove elements from the list until it is sorted in increasing order. For example the list <...
15k views

Eww, those bytes are gross

Write a program or function that, when given a string, filters out as many distinct bytes as it can and returns the cleaned string. However, since your program hates them, none of these bytes can be ...
2k views

Make a slow error quine maker!

As part of his answer to Make an Error Quine!, @Falko proposed the following algorithm: How to create your own solution in 2 minutes? Open a new file in an IDE of your choice. Bang your ...
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Khinchin's constant to as many decimal places as possible in 64 bytes or less

Khinchin's constant is a curious mathematical constant that, according to Wolfram MathWold, is "notoriously difficult to calculate to high precision". Here it is to 100 digits: 2....
31k views

Without using numbers, get the highest salary you can. But don't exaggerate!

As I'm applying for some jobs whose job advert doesn't state the salary, I imagined a particularly evil interviewer that would give the candidate the possibility to decide their own salary ...by "...
288 views

Convert ASCII art numbers to integers

Inspired by this game Challenge: Given an ASCII art string representing a number, output that number. Example: ...
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Code close to the challenge: Sum of integers

This is a simple challenge: Given a sequence of integers, find the sum of all integers in it. But with a twist. Your score is the Levenshtein distance between your code and the following phrase (The ...
435 views

A nasty little memory leak

Below Python code generates memory leak. Challenge: Fix the memory leak with minimal changes to the code as measured by Levenshtein distance to the original code. You may only change the code before ...
13k views

Wait, what language is this?

Recently I had the pleasure of writing a Haskell program that could detect if the NegativeLiterals extension was engaged. I came up with the following: ...
3k views

A Programming Puzzle of Mode Golf

Your task is to print the text Good morning, Green orb!, with every character repeated in place as many times as the most frequent byte in your source (the mode). ...
1k views

The number of reachable snake orientations

This challenge is not about the game Snake. Imagine a 2d snake formed by drawing a horizontal line of length n. At integer points along its body, this snake can ...
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A Multipurpose Quine

I personally love quines, but they all seem to be so... static. So why not create a quine that can do more. Challenge The challenge here is to create a quine that without any sort of input is a ...
2k views

Superpermutations

Introduction You're a criminal tasked with stealing some secret plans from the new tech startup Dejavu. You sneak in over the back wall, but find a door that requires a pin to open it. You recognize ...
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45 degree quine [closed]

A very simple golf this time, but should be fun to do. Challenge Output your code, but rotated 45 (or -45) degrees. E.g: lorem ipsum dolor sit amet becomes <...
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Print the Lost numbers

As a big fan of the Lost TV series, I always got intrigued by the sequence of numbers that repetitively appears on the episodes. These numbers are: $4, 8, 15, 16, 23, 42$ (A104101) Using any ...
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The real treasure was the numbers we made along the way

Your task is to write a program, function or snippet (yes, snippets are allowed) that simply outputs an integer. However, you must be able to separate your submission into prefixes that also produce ...
1k views

Meta-bowling Golf

Your task is to create the shortest program (A) that outputs another program (B) with the most unique bytes, which in turn outputs the original program (A). Essentially, you are golfing one half of a ...
2k views

Take It or Leave It: A Game Show for Computers

Context: A reclusive billionaire has created a game show to attract the world's best and brightest programmers. On Mondays at the stroke of midnight, he chooses one person from a pool of applicants ...
951 views

How fast can I say your program?

I recently decided to download some dictation software, in order to help with my writing. However, it doesn't work very well when I'm coding, since I have to change from saying words to symbols and ...
8k views

Your challenge is to write a polyglot that works in different versions of your language. When run, it will always output the language version. Rules Your program should work in at least two versions ...
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Write the longest period iterating quine bounded by 500 bytes

Your job is to create the longest period iterating quine, where the length of each program in the sequence is bounded by 500 bytes. That is, if you repeat the following steps: Start with your ...
7k views

Holy Hole In A Donut, Batman!

Some characters are more holy than others. Using as few unholy letters as possible, display the statement above. Challenge Write a full program to print ...
721 views

The longest period iterating quine

As we know, a quine is a program that outputs its own source code. However, it's also possible to write a program that outputs another, different program, that outputs the first program again. For ...
280 views

Cyclic Weak Levenquine

This question asking us to make a "Cyclic Levenquine" has gone unanswered. So today we will ask a slightly simpler version. In this challenge we will define a K-Levenquine to be a program whose ...
4k views

Adding without using a + or - sign

There have been many "Do __ without __" challenges before, but I hope that this is one of the most challenging. The Challenge You are to write a program that takes two natural numbers (whole numbers ...
592 views

Plight of the Concorde

Background The traveling salesman problem (TSP) asks for the shortest circuit that visits a given collection of cities. For the purposes of this question, the cities will be points in the plane and ...
91 views

determine if the circle is boxed in [closed]

Pretty simple challenge here. Who can make the fastest algorithm (lowest time complexity) to determine whether or not the circle is "boxed in" given the following setup? Input: Your program receives ...
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Write a Quine in Plain English

Write a quine that consists of real English words separated by single spaces. A "word" is defined as a string containing only lowercase and uppercase letters (...
293 views

Challenge Write two programs that: run in two different programming languages. These may not be two versions of one language. when one program is run, it outputs the second program, and vice versa....