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).

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Create the characters you can write on a MacOS US English Keyboard (as another OS will read them)

Introduction This is a small challenge I came up with while trying to make some compact code for my younger brother to use. I don't think it's particularly interesting, but I believe it presents some ...
Mel's user avatar
  • 9
-2 votes
0 answers
118 views

8-bit AVR integer division: best drop-in improvement over libgcc's __udivmodhi4 [closed]

Some programs use results of integer division: quotient, remainder, or both. Not all processors provide direct support for division in the instruction set, among them 8-bit AVRs (Microchip, formerly ...
greybeard's user avatar
3 votes
9 answers
2k views

nimi ale lon toki pona! (Every word in Toki Pona!)

"nimi ale lon toki pona" is a song by YouTuber jan Misali which lists 137 common words in the constructed language Toki Pona. This challenge is not a duplicate of "How high can you ...
3-1-4-One-Five's user avatar
7 votes
2 answers
245 views

Convert maximum values to bit widths

Background The newest version of the C standard, C23, adds preprocessor macros like INT_WIDTH, ULONG_WIDTH, and ...
Tavian Barnes's user avatar
17 votes
3 answers
900 views

Magical BF: BF code that works in two ways

Challenge In this challenge, we will use a language that is very similar to Brainfuck but slightly different. This variant of BF does not have any input and output commands; instead, it simply takes ...
Bubbler's user avatar
  • 76k
0 votes
2 answers
200 views

The many ways to skin a `cat` [duplicate]

The well known cat command simply copies its stdin directly to stdout unchanged. But there are plenty of other commandline tools that exist... What other commands ...
CarmenCarmen's user avatar
-2 votes
2 answers
256 views

Forward foo, reverse bar, but avoid dead code [closed]

So simple: Provide some code that outputs foo and with the reversed source outputs bar. But before you come up with something ...
Philippos's user avatar
  • 2,501
5 votes
9 answers
1k views

Print the banned characters based on the most common characters

This is an answer-chaining post, so in this challenge every answer (except the first answer) depends on the previous answer. The goal of this challenge is to output the restricted characters. The ...
Fmbalbuena's user avatar
  • 3,847
19 votes
29 answers
3k views

Restricted Meta-Cat

Your challenge, should you choose to accept it, is to write a program in a language of your choice that, when given a string (limited to printable ASCII) as input, outputs a new program in the same ...
noodle man's user avatar
  • 6,893
4 votes
5 answers
602 views

What is the smallest possible binary output you can generate

Here is a challenge: What is the shortest possible compiled program? Writing one line programs are fun, but they often lean on language libraries that get pulled into the final bits. How lean can you ...
Roger Hill's user avatar
16 votes
6 answers
4k views

I irradiate your source code, you irradiate your output

Your task is to write a program \$p\$ which outputs a string \$s\$ with the same length as \$p\$, where \$s \neq p\$. If I remove the \$n\$th byte from your program to get program \$q\$, then either \$...
Wheat Wizard's user avatar
  • 98.5k
1 vote
0 answers
61 views

How Many Staircases [duplicate]

Problem You're a staircase engineer on a house and realize you only have n rectangles to create a staircase. So you are tasked with finding the number of ways to ...
3.14's user avatar
  • 383
30 votes
44 answers
4k views

Repeat your program to print Fibonacci numbers

Write a program fragment so that, when repeated N times it prints the Nth Fibonacci number. For example, if your program is print(x) then: ...
mousetail's user avatar
  • 12.5k
10 votes
12 answers
2k views

Encrypting Emojis

Problem You are tasked with creating a program that performs emoji encryption on a given string of emojis. In this encryption scheme, each emoji is replaced by a unique character (from ...
3.14's user avatar
  • 383
20 votes
10 answers
2k views

How Turing complete is your language?

Find the maximum possible number of disjoint sets of characters, that are Turing complete subsets of your language. Rules: You can assume your Turing complete subset is contained in/called from a ...
bsoelch's user avatar
  • 6,015
8 votes
8 answers
645 views

Magic OEIS formulae (Robbers' thread)

This is the robbers' thread. See the cops' thread here. In this cops and robbers challenge, the cops will be tasked with writing an algorithm that computes some function of their choice, while the ...
dingledooper's user avatar
  • 22.7k
12 votes
9 answers
756 views

Magic OEIS formulae (Cops' thread)

This is the cops' thread. See the robbers' thread here. In this cops and robbers challenge, the cops will be tasked with writing an algorithm that computes some function of their choice, while the ...
dingledooper's user avatar
  • 22.7k
1 vote
1 answer
200 views

Most elegant one-liner to generate sqlite INSERTs

Challenge You find yourself in a bash terminal, and want to do some simple tests on sqlite3. So you issue the following command: ...
ChrisB's user avatar
  • 119
1 vote
0 answers
158 views

making a binary string palindrome using xor operations [closed]

Problem You are given a binary string A of length N. You can perform the following type of operation on the string A: Choose two different indices \$i\$ and \$j\$ (\$1 \le i\$, \$j \le N\$) Change \$...
hemanth's user avatar
  • 11
3 votes
4 answers
1k views

Write the smallest possible code in x86-64 to implement the "<=>" operator

Languages, such as C++, have introduced a new comparison operator: <=>. This operator returns -1, 0, or 1† when comparing two items together: −1 means the ...
Alexis Wilke's user avatar
19 votes
17 answers
2k views

Approximate my atomic weight

Each element on the periodic table of the elements has an atomic weight. For example, boron (element 5) has an atomic weight of 10.81. Your challenge is to write a program which takes as input the ...
Ginger's user avatar
  • 5,490
12 votes
3 answers
479 views

><> numbers metagolf

I struggle to easily encode big numbers in ><>. If only there was a program that could find the best way for me? What is ><> ...
mousetail's user avatar
  • 12.5k
25 votes
54 answers
3k views

Range of ASCII values

Your task Given a string, output the range of ASCII values. Example Let's say we have the string Hello. We get the ASCII values: ...
The Thonnu's user avatar
39 votes
5 answers
4k views

50 digits of π in HQ0-9+-INCOMPUTABLE?

Background HQ0-9+-INCOMPUTABLE?! is a half-joke programming language introduced in Internet Problem Solving Contest 2011, Problem H. HQ9+ is an esoteric programming language specialized for certain ...
Bubbler's user avatar
  • 76k
3 votes
4 answers
872 views

A multidimensional strategy challenge

The wizard is determined to pose the most challenging challenge yet for which he believes the previous solution techniques will not work. He decides to go multidimensional. If there is a number line ...
user avatar
17 votes
11 answers
2k views

Numbers vs. Strings: Language fitness challenge

inspired by thejonymyster's idea Rules This challenge is about finding languages that are very suitable for one task but quite the opposite in the other. The two tasks share a theme, but Task 1 is ...
Bubbler's user avatar
  • 76k
8 votes
0 answers
421 views

Turing Machine that outputs pi

Turing Machine Preliminaries A Turing machine is specified by the following data A finite set of symbols S = \$\{s_1,s_2,...\}\$ A finite set of states M = \$\{m_1,m_2,...\}\$ A partially defined ...
QCD_IS_GOOD's user avatar
25 votes
11 answers
3k views

Write a program with the smallest width

Print or return the following text: Hello world! The quick brown fox jumps over a lazy dog. However, your submission will not be scored in bytes. Instead, ...
Sisyphus's user avatar
  • 14.8k
5 votes
4 answers
614 views

Strategy: The cunning cousin witch

The wizard has a cunning cousin who is a witch. She looks down on the wizard, regarding him and his puzzles as mathematically naive. On reading his latest puzzle, she scorned him for always asking ...
user avatar
5 votes
2 answers
925 views

Optimal strategy to defeat the wizard

In this game, you can look inside one box at a time chosen by you. When you do that, you can see how many coins there are in that box. The wizard has one last twist for you. At any point, you can ...
user avatar
20 votes
12 answers
3k views

Optimal strategy for wandering robots

If the agent is at the origin it always moves right when you choose it. The goal is to get one agent to 10. The cost is the sum of the square of the total number of moves (left or right) taken by each ...
user avatar
6 votes
2 answers
297 views

Case Conversion Polyglot

Your task is to write a program that performs case conversion from plain text, and other case formats, into one of the specified formats below. Inputs will be either plain lowercase text, or one of ...
Dom Hastings's user avatar
  • 23.5k
5 votes
7 answers
834 views

Typo resistant pin codes [closed]

Background I was working on a system where for convenience (not security) people could use four digit codes to identify themselves. I figured this is something that may actually be useful in many real ...
Dennis Jaheruddin's user avatar
5 votes
0 answers
246 views

Find the best character arrangement

You want to write your English essay. However, all characters on your keyboard broke other than the arrow keys and the enter key. You want to find out how to place the characters so you can write your ...
Command Master's user avatar
19 votes
11 answers
2k views

Write a near crystalline program

A pristine program is a program that does not have any errors itself but will error if you modify it by removing any contiguous substring other than the entire program. A crystalline program is sort ...
Wheat Wizard's user avatar
  • 98.5k
1 vote
1 answer
258 views

Implement the slowest possible sorting algorithm that retains a fast best case [closed]

I have recently been on a quest to create really really slow sorting algorithms that make Bogosort seem like it is the best. The task is simple: Sort an array of integers in as long average time as ...
Eknoma's user avatar
  • 27
-12 votes
5 answers
365 views

12 with no 1234567890, but polyglot

This is my 12th question, so I thought of this idea. Goal: Output 12, with any preceding or trailing whitespace permitted In as many languages as possible (where different versions or flags count as ...
Number Basher's user avatar
29 votes
21 answers
4k views

Add a hidden language to a polyglot

Inspired/mostly copied but I don't think it's a dupe. Also Inspired. In this challenge, you will create polyglots that include all languages from previous answers, and another language which you won't ...
emanresu A's user avatar
  • 37.8k
6 votes
1 answer
670 views

Irradiated Polyglots

Design a function or program that, when run normally, outputs the triangular numbers. However, when any single character is deleted, the program/function should not function in the original ...
Romanp's user avatar
  • 1,357
5 votes
1 answer
187 views

BitCycle Metagolf

Background BitCycle is a two-dimensional Turing-complete programming language involves moving bits around a playfield. Because I am too lazy to write BitCycle programs myself, you will be writing a ...
Aiden Chow's user avatar
  • 13.3k
27 votes
28 answers
4k views

What's the Missing Code? (Cops)

Cops' Challenge Robbers' challenge here. It has now been four days since the challenge was posted so all new answers should be marked as non-competing in the title. These answers can still be cracked ...
Lecdi's user avatar
  • 1,155
3 votes
0 answers
189 views

Calculate the probability of getting this hand in n tries [closed]

Imagine there is a card game where the primary objective of the game is to get 4 of one card in your hand. Game mechanics Each player starts of with 10 cards in their hand. The remaining 32 cards (...
violetorigin's user avatar
4 votes
3 answers
277 views

Find All Digitroot Cyclic Sequences With Length Greater Than One

Digital sum, DR, Digit root is the iterative process of summing digits of a number until you end up with a single digit root number: e.g. digit root of 12345 is 6 since 1 + 2 + 3 + 4 + 5 = 15 = 1+5. ...
jixperson's user avatar
  • 195
3 votes
2 answers
278 views

Implement constant-latency branchless multiplication efficiently

Modern hardware can perform multiplication very fast in a constant latency of 3~4 cycles. But some tiny chips for embedded environments sometimes lack hardware multiplication, which has to be emulated ...
xiver77's user avatar
  • 2,365
10 votes
3 answers
1k views

Build an optimizing Brainfuck compiler/interpreter

the goal Build an optimizing Brainfuck implementation. Whether it is a compiler, an interpreter, a JIT compiler, or whatever else is up to you. scoring A reference implementation (...
xiver77's user avatar
  • 2,365
6 votes
3 answers
323 views

Write a regex that would increment a 2-digit hexadecimal number

Your regex will receive a string of the form !XX! #<extra> where X is any hexadecimal digit (0-9 and A-F capital letters ...
Itay123's user avatar
  • 71
13 votes
1 answer
587 views

Longest infinite loop in 5 states

Challenge Statement The goal of this challenge is to build the 5 state Infinite Time Turing Machine that takes the longest to halt. Since Infinite Time Turing Machines can run for infinite time your ...
Wheat Wizard's user avatar
  • 98.5k
6 votes
2 answers
297 views

Generate Matching Regexes

Write a program that takes two lists of strings and generates a javascript regex that fully matches all the strings in the first list and matches none of the strings in the second list. To be specific ...
user197974's user avatar
  • 1,161
10 votes
8 answers
611 views

Biggest katlani noun dictionary in 400 bytes

Katlani is a constructed language being designed in chat. In this challenge, your goal is to print the largest dictionary of katlani nouns possible in 400 bytes or less. Task In 400 bytes or less, ...
Rydwolf Programs's user avatar
9 votes
8 answers
481 views

From code to golf (Robbers' thread)

This is a cops-and-robbers challenge, the cops' thread is here You can change the word code into golf by changing a letter at a ...
emanresu A's user avatar
  • 37.8k

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