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28
votes
17answers
2k views

Compute the multinomial coefficient

Time for another easy challenge in which all can participate! The multinomial theorem states: The expression in parentheses is the multinomial coefficient, defined as: Allowing the terms ki to ...
15
votes
9answers
2k views

Build a polyglot for Hello World

Produce a text file that prints "Hello World!" in as many programming languages as possible when compiled/interpreted, while also being as short as possible. The score for your submission is ...
393
votes
156answers
251k views

Write a program that makes 2 + 2 = 5 [closed]

Write a program that seemingly adds the numbers 2 and 2 and outputs 5. This is an underhanded contest. Your program cannot output any errors. Watch out for memory holes! Input is optional. ...
240
votes
56answers
50k views

Survival Game - Create Your Wolf

The Board The Board is a two dimensional array of cells. Cells are populated by Animals. Every day, all Animals on the Board simultaneously make one move. If two or more Animals move to the same cell, ...
122
votes
187answers
31k views

Sing Happy Birthday to your favourite programming language

Your favourite programming language has just had a birthday. Be nice and sing it the Happy Birthday song. Of course you should accomplish this by writing a program in that language. The program takes ...
44
votes
39answers
16k views

Draw A Sierpinski Triangle

The Sierpinsky Triangle is a fractal created by taking a triangle, decreasing the height and width by 1/2, creating 3 copies of the resulting triangle, and place them such each triangle touches the ...
96
votes
39answers
12k views

The Versatile Integer Printer

Write a piece of code that is executable in at least three different languages. The code must output the integer 1 in language number one, ...
99
votes
9answers
6k views

Write an interpreter for 99

99 (pronounced "ninety-nine") is a brand new Esoteric programming language (not to be confused with 99, note the italics). Your task in this challenge is to write an interpreter for 99 that is as ...
49
votes
88answers
8k views

Alphabet triangle

You are to print this exact text: ...
90
votes
23answers
11k views

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 ...
56
votes
79answers
11k views

Play the “bzzt” game

Winner: Aditsu's CJam answer! A whopping 25 bytes! Nice! You may continue to submit your answer, however you can no longer win. Original post kept for posterity: The "Bzzt" game is a game ...
43
votes
21answers
5k views

One Ring to rule them all. One String to contain them all

Objectives: Output a String which contains every positive integer strictly below 1000. The obvious answer would be to concatenate every one of them, and that would create a String of 2890 characters (...
74
votes
190answers
13k views

Count up forever

Write a program that counts up forever, starting from one. Rules: Your program must log to STDOUT or an acceptable alternative, if ...
64
votes
115answers
9k views

Make a ;# interpreter

I recently created a new language called ;# (pronounced "Semicolon Hash") which only has two commands: ; add one to ...
44
votes
43answers
8k 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 ...
37
votes
8answers
4k views

Shortest terminating program whose output size exceeds Graham's number

Write the shortest possible program (length measured in bytes) satisfying the following requirements: no input output is to stdout execution eventually terminates total number of output bytes exceeds ...
66
votes
111answers
7k views

Print/Output the L-phabet

Inspired by George Gibson's Print a Tabula Recta. You are to print/output this exact text: ...
53
votes
73answers
7k views

Test a number for narcissism

A Narcissistic Number is a number which is the sum of its own digits, each raised to the power of the number of digits. For example, take 153 (3 digits): 13 + 53 + 33 = 1 + 125 + 27 = 153 1634: ...
40
votes
65answers
6k views

Greatest Common Divisor

Your task is to compute the greatest common divisor (GCD) of two given integers in as few bytes of code as possible. You may write a program or function, taking input and returning output via any of ...
41
votes
69answers
7k views

Is it a leap year?

This challenge is quite simple. You will take an input which will be a year from 1801 to 2400, and output if it is a leap year or not. Your input will have no newlines or trailing spaces: ...
23
votes
51answers
6k views

Is string X a subsequence of string Y?

Given strings X and Y, determine whether X is a subsequence of Y. The empty string is regarded as a subsequence of every string. (E.g., '' and ...
36
votes
47answers
6k views

Catalan Numbers

The Catalan numbers (OEIS) are a sequence of natural numbers often appearing in combinatorics. The nth Catalan number is the number of Dyck words (balanced strings of parenthesis or brackets such as ...
22
votes
7answers
2k views

Tips for golfing in Julia

What general tips do you have for golfing in Julia? I'm looking for ideas that can be applied to code golf problems in general that are at least somewhat specific to Julia (e.g. "remove comments" is ...
16
votes
7answers
763 views

Tips for golfing in Prolog

What general tips do you have for golfing in Prolog? I am looking for ideas that can be applied to code golf problems in general that are at least somewhat specific to Prolog (e.g. one letter ...
25
votes
8answers
1k views

All your bijective base are belong to us

Background A bijective base b numeration, where b is a positive integer, is a bijective positional notation that makes use of b symbols with associated values of 1 to b. Unlike its non-bijective ...
16
votes
31answers
2k views

Spell out the Revu'a

Actually not inspired neither by Atbash Self Palindromes nor by Generalized Gematria Calculator. Given a string s of length n, output the Revu'a sequence, which is the first character of s, the first ...
9
votes
5answers
2k views

Words from periodic table of elements [closed]

Back when I was a freshman in highschool taking chemistry, I'd look at the periodic table of elements and spell dirty words out with the number of the elements (HeCK would be 2619, 2-6-19). I was ...
27
votes
23answers
2k views

Case Permutation

Who needs to compare things case insensitively when you're able to generate every permutation of uppercase and lowercase? No one! That's the answer. No one does. Your task is to achieve this feat; ...
14
votes
49answers
7k views

Sum of positive integers. [closed]

Problem: Given a set of integers, find the sum of all positive integers in it. Input: t – number of test cases [t < 1000] On each of next t lines, an integer N [-1000 ≤ N ≤ 1000] Output The ...
1078
votes
6answers
240k views

Build a working game of Tetris in Conway's Game of Life

Here is a theoretical question - one that doesn't afford an easy answer in any case, not even the trivial one. In Conway's Game of Life, there exist constructs such as the metapixel which allow the ...
228
votes
180answers
35k views

Evolution of “Hello World!”

This contest is officially over, the winner is jimmy23013. Congratulations! The challenge is to make a program that prints Hello World! to stdout. The catch is ...
143
votes
244answers
27k views

Unscramble the Source Code

Note: This challenge is now closed to new cop submissions. This is to ensure that no one can post submissions that only remain uncracked because there aren't enough robbers interested in the challenge ...
107
votes
102answers
13k views

Make an error quine!

Your challenge: write a "program", for a language of your choice, that causes the compiler/interpreter/runtime to produce error output when compiling/running your program which is identical to your ...
66
votes
14answers
5k views

Write a polyglot that prints the language's name

Your task is to write a program that executes in as many languages as possible, with as few characters as you can. To avoid trivial solutions, the program must print the name of the language it was ...
50
votes
10answers
9k views

Build a random number generator that passes the Diehard tests

While there are many code golf questions on here involving randomness, I haven't seen one yet that actually asks for building an algorithmic pseudorandom number generator. There's this one that asks ...
32
votes
12answers
2k views

Tips for golfing in vim

I've recently realized how vim works great for golfing, especially for kolmogorov-complexity. Also, according to meta vim is a perfectly acceptable 'programming language' at least, for the scope of ...
28
votes
17answers
10k views

Transform number into 7-segment display pattern

Given two arbitrary numbers A,B. Print number B as a Digital LED Pattern where A is the scale. input: 1 2320451640799518 ouput: ...
26
votes
7answers
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 ...
66
votes
36answers
11k views

Enlarge ASCII art

In this challenge, you must take multiline ASCII art as input, such as: ...
29
votes
37answers
5k views

Implement hyperexponentiation/tetration without the use of '^'

The Challenge Implement tetration (aka Power Tower or Hyperexponentiation) with the least amount of characters. The Conditions Don't use the 'power' operator or its equivalents (such as ...
28
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 ...
56
votes
35answers
7k views

Print the N-bonacci sequence

This isn't very widely known, but what we call the Fibonacci sequence, AKA 1, 1, 2, 3, 5, 8, 13, 21, 34... is actually called the Duonacci sequence. This is ...
45
votes
18answers
5k views

Sᴍᴀʟʟ Cᴀᴘꜱ Cᴏɴᴠᴇʀᴛᴇʀ

Portable Spec. Iɴꜱᴘɪʀᴇᴅ ʙʏ @ConorO'Brien's ᴜꜱᴇʀɴᴀᴍᴇ. Aʟꜱᴏ ᴛʜᴀɴᴋꜱ ᴛᴏ @Dᴏᴏʀᴋɴᴏʙ ꜰᴏʀ ꜱʜᴏᴡɪɴɢ ᴍᴇ ᴛʜᴇ ᴇxɪꜱᴛᴇɴᴄᴇ ᴏꜰ ǫ ᴀɴᴅ x. Sᴍᴀʟʟ ...
35
votes
48answers
3k views

Boustrophedonise

Related but very different. A boustrophedon is a text where every other line of writing is flipped or reversed, with reversed letters. In this challenge, we will just reverse every other line, but ...
35
votes
78answers
7k views

Notcalc (Calculate the wrong answer)

Goal: Given two natural numbers (integers from 0 to infinity), output a number that is not the sum of those numbers, but is a natural number. Example solutions (TI-Basic): ...
30
votes
41answers
9k views

Will Jimmy fall off his platform?

Backstory Meet my friend Jimmy: /o\ Jimmy is a little character who likes to stand on platforms. Here's Jimmy safely standing on a platform: ...
23
votes
10answers
2k views

Tips for golfing in Lua

What general tips do you have for golfing in Lua? I'm looking for ideas that can be applied to code golf problems in general that are at least somewhat specific to Lua (e.g. "remove comments" is not ...
22
votes
11answers
4k views

Generate a Kolakoski sequence [duplicate]

Definition1 A Kolakoski sequence is a self-describing infinite sequence {kn} of alternating blocks of 1's and 2's, given by the following rules: k0 = 1 kn = the length of the (n+1)'th ...
21
votes
54answers
6k views

Display number of occurrences for every character in an input string

The code should take a string as input from keyboard: The definition of insanity is quoting the same phrase again and again and not expect despair. The output ...
63
votes
47answers
6k views

N-dimensional N^N array filled with N

In: Enough memory and a positive integer N Out: N-dimensional N^N array filled with N, where N^N means N terms of N-by-N-by-N-by... Examples: 1: [1] ...

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