Questions tagged [restricted-source]

Imposes a restriction on the source code used to solve the challenge, for example, having no numbers in the source code.

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614 votes
315 answers

Produce the number 2014 without any numbers in your source code

Note to challenge writers as per meta consensus: This question was well-received when it was posted, but challenges like this, asking answerers to Do X without using Y are likely to be poorly received....
  • 34.3k
260 votes
133 answers

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 "...
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233 votes
28 answers


You have been hired for your tech knowledge as a Secret Agent's sidekick to ensure that the good guy can get his job done and the world can be saved. This is your last mission before retiring with a ...
  • 4,077
168 votes
70 answers

How high can you count?

Challenge: Your task is to write as many programs / functions / snippets as you can, where each one outputs / prints / returns an integer. The first program must output the integer ...
145 votes
77 answers

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 ...
140 votes
88 answers

Largest Number Printable

Your goal is to write a program that prints a number. The bigger the number, the more points you'll get. But be careful! Code length is both limited and heavily weighted in the scoring function. Your ...
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133 votes
138 answers

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 ...
122 votes
95 answers

ASCII's 95 Characters...95 Movie Quotes

Update: The winner has been decided, but the challenge is not over! Finally, nearly 3 months after the question first started, someone has remained the last answerer for more than a week! ...
117 votes
19 answers

"Hello, World!" in zero lines of code

NPM's sloc is a moderately popular tool for counting source lines of code in a file. The tool will attempt to strip out both single and multiline comments and count the remaining lines in order to get ...
  • 13.5k
115 votes
75 answers

I'm a palindrome. Are you?

There have been a couple of previous attempts to ask this question, but neither conforms to modern standards on this site. Per discussion on Meta, I'm reposting it in a way that allows for fair ...
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103 votes
64 answers

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. ...
  • 12.2k
94 votes
36 answers

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 ...
  • 46.9k
92 votes
23 answers

Programming a Pristine World

Let's define a pristine program as a program that does not have any errors itself but will error if you modify it by removing any contiguous substring of \$N\$ characters, where \$1 \le N < \text{...
88 votes
20 answers

Pristine and Unique Code Bowling

Your challenge is simple: write as long of a pristine program as possible in the language of your choice using only unique bytes. (The full definition of a pristine program, copied from that link, is ...
  • 1,445
86 votes
102 answers

Hello World 0.0!

source: Dilbert, September 8, 1992 I'm hoping to add a new twist on the classic "Hello World!" program. Code a program that outputs Hello World! without: String/...
  • 3,234
84 votes
210 answers

The Letter A without A

Your task is to display the letter "A" alone, without anything else, except any form of trailing newlines if you cannot avoid them, doing so in a program and/or snippet. Code that returns (instead of ...
84 votes
132 answers

Loop without 'looping' [closed]

A question similar to this has been asked a couple of years ago, but this one is even trickier. The challenge is simple. Write a program (in your language of choice) that repeatedly executes code ...
  • 1,043
78 votes
70 answers

Hello world! with limited character repetition

In a language of your choice, write a program that exactly outputs the characters Hello world! followed by a newline. The code: should not use any character more ...
  • 2,761
77 votes
38 answers

Non-discriminating Programming

We say a string is non-discriminating if each of the string's characters appears the same number of times and at least twice. Examples "aa!1 1 !a !1" is non-...
  • 25.4k
73 votes
119 answers

Print the alphabet without using each vowel

Inspiration: in 1939, a man named Ernest Vincent Wright wrote a novel called Gadsby without using the letter 'e'. Your task is to write a set of (up to 5) programs in any language (which has a text-...
  • 1,231
73 votes
94 answers


Write a program that produces an output such that: At least three distinct characters appear. The number of occurrences of each character is a multiple of 3. For example, ...
  • 7,849
73 votes
29 answers

2016 Time Capsule String: How Versatile Is Your Language?

About a year ago on Dec 31, 2015, I had the idea that: We should make a time capsule string. Everybody gets to add one character and next new years we'll see who can make the best program out of all ...
72 votes
183 answers

Output your Score!

Challenge: The concept is simple enough: write a full program to output its own code golf score! Output should only be the byte count of your program and a trailing ...
  • 1,786
72 votes
155 answers

Print X without X (cop's thread)

This is the cop's thread of a cops-and-robbers challenge. You can view the robber's thread here A pretty common beginner style question is to print some string, but there's a catch! You need to do it ...
  • 92.2k
72 votes
81 answers

No strings (or numbers) attached

If you like this, consider participating in: The Official Dyalog APL 2016 Year Game The monthly Dyalog APL 2017 Code Golf Challenge Make 12 snippets/expressions, in the same language, that result in ...
  • 29.1k
72 votes
24 answers

Tweetable hash function challenge

In this code-challenge you will write a hash function in 140 bytes1 or less of source code. The hash function must take an ASCII string as input, and return a 24-bit unsigned integer ([0, 224-1]) as ...
  • 38.9k
66 votes
20 answers

Just repeat yourself

Write a program that outputs Do not repeat yourself! Your program code must respect the following constraints : its length must be an even number each ...
  • 8,413
66 votes
11 answers

Only Even Bytes

The scenario Lately you have been noticing some strange behavior with your favorite text editor. At first it seemed that it was ignoring random characters in your code when writing to disk. After a ...
  • 92.2k
65 votes
20 answers

Hash collision: "NO" means "YES"

This Code Golf was inspired by the recent Daily WTF article You Can't Handle the True!, which features a string comparison written as: ...
  • 6,571
64 votes
62 answers

Write lines in detention

Introduction Bad news guys - you got detention. Your English teacher doesn't understand this site and wants you to "stop doing math on your digital dohickeys, this is English class!" She ...
  • 3,436
61 votes
147 answers

Print 0 to 100 without 1-9 characters

Print 0 to 100 without using characters 1,2,3,4,5,6,7,8,9 in your code. Seperator of numbers can be comma, whitespace or newline. Shortest code wins.
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60 votes
31 answers

Output the text "Code Bowling"

Code-Bowling You've been hired by Brunswick Bowling to create a simple program to output the text Code Bowling on their monitors. This company is worth a pretty ...
59 votes
35 answers

Print the phrase "And she said, 'But that's his.'" using only the alphabet

Print the phrase And she said, 'But that's his.' using only the following characters: ...
59 votes
57 answers

Print every printable ASCII character without using it

In a programming language of your choice, write 95 programs, each of which outputs a different one of the 95 printable ASCII characters without that character occurring anywhere in the program. For ...
58 votes
19 answers

Write the whole of the holed using the unholed

The ASCII characters from decimal code 33 to 126 are: !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~ ...
57 votes
43 answers

All Your Base Are Belong To Us (Restricted)

Input must not be required, and output must read "All your base are belong to us". Restrictions No external resources. Plus a minimum of two of the ...
56 votes
161 answers

Output programming language name

Challenge: In the programming language of your choice, take no input and output your programming language's name. Fair enough, right? Restrictions: You can't use any character that is included in ...
  • 3,022
56 votes
85 answers

yes is 91 lines long

yes, from coreutils, is 91 lines long. Many of them are comments, but that is still WAY too long. Edit from September 2019: the source file grew over the past five ...
56 votes
24 answers

Significant Whitespace

We define whitespace to be any of the three characters, tab (0x09), newline (0x0A) or space (0x20). For this challenge, you're to write two programs or functions in the same programming language, ...
56 votes
36 answers

Conway's Monster

This challenge is in honor of mathematician John Conway who passed away April 11, 2020 due to COVID-19. He was famous for coming up with the Game of Life cellular automaton and many other mathematical ...
55 votes
20 answers

Exit Code Golfing

Inspired by this default for IO. The Task Write a program that, given an input integer x between 0 and 255, crashes with exit code ...
54 votes
52 answers

Print all ASCII alphanumeric characters without using them

Challenge Print the following characters: abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890 The catch is that you may not use any one of them in ...
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54 votes
7 answers

Duct tape can fix Mother's Day

Based on the Duct tape can fix anything question, that was too broad, with very similar rules. Only this time the objective is very specific: The challenge Your mission is to make a program that ...
54 votes
32 answers

Does it Lead or Follow?

In this challenge you are to write a program or function, that takes a string as input and outputs one of two possible values. We will call one of these values truthy and one falsy. They do not need ...
  • 92.2k
52 votes
2 answers

JSF**k with only 5 symbols?

This is not a challenge but a question, I figured it was on topic because of Non-challenge questions that are related to solving programming puzzles or a particular type of challenge are also on ...
  • 1,538
50 votes
66 answers

Divide a number by 3 without using *, /, +, -, % operators [closed]

Quoting this question on SO (Spoiler alert!): This question has been asked in an Oracle interview. How would you divide a number by 3 without using *, /, +, -, %, operators? The number ...
  • 3,579
50 votes
67 answers

Depalindromize this string!

Given a palindrome generated according to this challenge, depalindromize it. Test cases ...
  • 10.4k
50 votes
5 answers

Multiply with restricted operations

There's a 500 rep unofficial bounty for beating the current best answer. Goal Your goal is to multiply two numbers using only a very limited set of arithmetic operations and variable assignment. ...
  • 141k
49 votes
86 answers

Hack into a Lottery

You've recently made an account on a dodgy gambling site, where for a fee of 25 dollars, they will pay you back a random amount between 0 and 50 dollars. After getting around 5 dollars twice, you ...
  • 3,337
49 votes
24 answers

A Chiral Puzzle

A shape is chiral if no amount of rotation can make it look like it's mirror image. In this puzzle we will be writing chiral computer programs. For this puzzle we will think of a program as a ...
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