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).

Filter by
Sorted by
Tagged with
8
votes
2answers
329 views

Find the largest recurring prime

Inspired by Find the largest fragile prime A recurring prime (or whatever you choose to call it) is a prime that, when removing leading digits, always remain prime regardless of how many digits are ...
2
votes
2answers
293 views
+50

Hash bomb filtrate

Pipe a short stream to the following Java program run with accompanying command line options, such that it prints true. ...
31
votes
15answers
6k views

Fastest yes in the west

There has been a question about yes in the past, but this one is slightly different. You see, despite yes having a rather long size, it is incredibly fast. Running ...
2
votes
0answers
94 views

Predictor Generator [closed]

Write a program that when given a string \$S\$, it generates a program of the same language as itself. The generated program, when given a continuous substring of \$S\$, should predict the next ...
4
votes
5answers
272 views

Find the most important character

Find the most important character The challenge is to write a program that outputs the most occurrent character in the input string, excluding these bracketing characters ...
1
vote
0answers
49 views

Shortest Sorting algorithm [duplicate]

So, you need to create the shortest sorting algorithm with a resonably fast run time. It could be any sorting algorithm. Test code: ...
3
votes
1answer
209 views

Estimate the mean minimum Hamming distance

Task Inputs \$b \leq 100\$ and \$n \geq 2\$. Consider \$n\$ binary strings, each of length \$b\$ sampled uniformly and independently. We would like to compute the expected minimum Hamming distance ...
-5
votes
5answers
284 views

Approximating the amount of prime numbers below `x`

Background We define the prime-counting function, \$\pi(x)\$, as the number of prime numbers less than or equal to \$x\$. You can read about it here. For example, \$\pi(2) = 1\$ and \$\pi(6) = 3\$. ...
2
votes
0answers
69 views

Selfish Programs [duplicate]

The Challenge Write two programs P and Q such that: P and ...
14
votes
1answer
377 views

Is everything in order?

Challenge: Input: a string, consisting of only printable ASCII characters Output: a truthy/falsey value whether its characters are in alphabetical order (based on their UTF-8 unicode values), from ...
4
votes
2answers
168 views

Inter-language 2-cycle quine [duplicate]

Challenge Create 2 programs A and B The output of program A is exactly program B The output of program B is exactly program A Neither program should depend on inputs to yield the correct output A ...
9
votes
1answer
384 views

Caddyshack or: How to compress already-golfed code

In golf, a knowledgable caddie helps an already good golfer to be even better. In this challenge, you build a "caddie" to help you code golf. In particular, your caddie will compress golfed code in ...
8
votes
4answers
807 views

Polyglot self-interpreter time

Your task is to make a program which interprets the language it is run in, but also works in many languages. Let's say you make a Brainfuck-Underload self-interpreglot, as it will be called. Run in ...
6
votes
1answer
566 views

Average number of strings with Levenshtein distance up to 3

The Levenshtein distance between two strings is the minimum number of single character insertions, deletions, or substitutions to convert one string into the other one. Given a binary string \$S\$ of ...
20
votes
4answers
418 views

Hexagonify™ a String Block

Sandbox What is Hexagonification™? Hexagonification™ is a transformation that creates a hexagon with 3 copies of a rectangle block, each skewed to the right by 30 degrees and then ...
29
votes
5answers
2k views

Longest Prime Sums

Sandbox There are special sets S of primes such that \$\sum\limits_{p\in S}\frac1{p-1}=1\$. In this challenge, your goal is to find the largest possible set of primes that satisfies this condition. ...
-1
votes
1answer
180 views

Polyglot Iterative Quine

Introduction A polyglot is a program that is valid in multiple languages at once. An iterative quine is a program that outputs another program that outputs another program that outputs the source of ...
21
votes
19answers
2k views

Smallest Fibonacci Multiples

Sandbox Background (not necessary for the challenge) A standard number theory result using the pigeonhole principle is the fact that given any natural number k, there is a Fibonacci number that is a ...
24
votes
13answers
4k views

Largest smallest gap

Write a function or program which takes as input a set of distinct, non-negative integers \$\{x_1, \ldots, x_n\}\$ and outputs the smallest gap between any two values in the set, i.e. \$\min_{i\neq j}|...
8
votes
0answers
277 views

Morpion solitaire

Morpion solitaire This is a game that I remember having learnt from my grandparents in my childhood. Initially I didn't know the name. G B has found it to be Join Five (or less ambiguously - Morpion ...
16
votes
3answers
2k views

How divisible are you?

You are to create a program which, when given a positive integer \$n\$, outputs a second program. This second program, when run, must take a second positive integer \$x\$ and output one of two ...
14
votes
1answer
395 views

How short can you get?

You are to write a program that, when given an integer between 1 and 5 (or 0 and 4 if you wish to use 0-indexing), outputs one of Code, ...
3
votes
1answer
127 views

Gaussian integer division reminder [closed]

Gaussian integer is a complex number in the form \$x+yi\$, where \$x,y\$ are integer and \$i^2=-1\$. The task is to perform such operation for Gaussian integers \$a,b\$, that \$a=q \cdot b+r\$ and \$|...
11
votes
3answers
526 views

A guess the word game

A guess the word game The agreed dictionary. All words are 6 letters long with all letters distinct Rules: This is a game of two players and the task will be to implement Player 2. Player 1 ...
-5
votes
7answers
270 views

Busy beaver of sorts [duplicate]

I'm surprised this hasn't been done yet, but here we go. Create a program which prints some number of 1s (ideally as large as possible) before halting. The rules are simple: Your program is bounded ...
22
votes
42answers
6k views

Hell0 W0rld! scored by ASCII values

Write a program that outputs Hell0 W0rld!. It must match this output exactly, including capitalization, zeroes instead of o's, exactly one space, etc. Trailing ...
10
votes
7answers
443 views

A Change in Perspective

In this challenge you will write a piece of text which when viewed from two different angles will create two different programs. Your string as viewed from above must take a string containing only ...
14
votes
0answers
449 views

Gerrymander North Carolina

The challenge How well can you gerrymander North Carolina into 13 voting districts? In this challenge, you use the following files to draw different maps for Republicans and Democrats. File 1: ...
17
votes
2answers
600 views

Number of distinct tilings of an n X n square with free n-polyominoes

The newest "nice" OEIS sequence, A328020, was just published a few minutes ago. Number of distinct tilings of an n X n square with free n-polyominoes. This sequence counts tilings up to symmetries ...
10
votes
2answers
828 views

Find the largest root of a polynomial with a neural network

The challenge Find the smallest feedforward neural network such that, given any 3-dimensional input vector \$(a,b,c)\$ with integer entries in \$[-10,10]\$, the network outputs the largest (i.e., "...
15
votes
1answer
754 views

Sort with a neural network

The previous neural net golfing challenges (this and that) inspired me to pose a new challenge: The challenge Find the smallest feedforward neural network such that, given any 4-dimensional input ...
21
votes
2answers
845 views

Create a uniquely solvable crossword … without clues

Can you imagine solving the New York Times crossword puzzle without any clues? Maybe not with all of the creativity and new words and phrases appearing in modern crosswords, but with a fixed word ...
-1
votes
4answers
339 views

Compress my Malbolge!

Background Malbolge is truly intriguing language. But programs written in it are also extraordinairly huge (and in some cases, unpostable on PPCG). Your challenge (shall you accept it) is, to ...
-3
votes
2answers
216 views

Write a “hello world” program that can be compiled/interpreted as two different languages simultaneously [duplicate]

Rules: Your program must print "hello world" when executed Your program must be interpretable or compilable into 2 or more languages Your program must require no input or arguments Languages with ...
-9
votes
1answer
167 views

Bot Problem.How to solve this problem in c? [closed]

Programming problem: In BotLand, Robots can understand all words of any combination of letters and letters with leading or trailing (not both) numeric value. Given a word W (string of alphanumeric). ...
1
vote
9answers
774 views

Lazy brainfuck programmer [closed]

Background Joe is working on his new Brainfuck answer on Codegolf. The algorithm he's using to solve the challenge is a bit complicated, so Joe came up with idea of simplifying his Brainfuck notation ...
13
votes
2answers
661 views

Create the least compressible picture

"A picture is worth a thousand words"—so the old saying goes. The average word is about four characters long, so a picture conveys 4kB of information. But how much entropy, rather than information, ...
34
votes
15answers
7k views

Generate Brainfuck for the numbers 1–255

Write a program that, for the numbers 1 through 255, prints out BF code that will produce the given number in some byte of the array, plus a newline. For example, the first four lines of the output ...
2
votes
3answers
155 views

Golf range minimum queries of a list [closed]

(Inspired by the first problem solved in Stanford’s advanced data structures course.) Despite the academicese-heavy name, the problem we're going to solve is almost unbearably simple. We have a list ...
14
votes
3answers
453 views

Bridge the Gaps

Given a black and white image with a white background and a set of black dots, paint a set of white pixels red, such that there is a path between each pair of black pixels. Details A path is a set ...
37
votes
27answers
4k views

Cops: The Hidden OEIS Substring

This is a Cops and Robbers challenge. This is the cop's thread. The robber's thread is here. As a cop, you must pick any sequence from the OEIS, and write a program p that prints the first integer ...
4
votes
0answers
102 views

Make a slow monotonic injection [duplicate]

In 256 bytes or fewer write a function, \$f\$, from the positive integers to the positive integers that is: Monotonic: larger inputs always map to larger outputs. (\$a < b \implies f(a) < f(b)\$...
12
votes
2answers
569 views

Counting generalized polyominoes

This challenge will have you count pseudo-polyforms on the snub square tiling. I think that this sequence does not yet exist on the OEIS, so this challenge exists to compute as many terms as possible ...
3
votes
2answers
765 views

Point-free madness

This challenge is about Haskell point-free style polynomial functions. Although you don't need to know Haskell language to do this challenge, Haskellers might have an advantage here. Point-free ...
5
votes
7answers
401 views

Print the previous answer in reverse - with a catch (pt. 2)

Your challenge is very simple: output the previous answer, in reverse. However, as with this similarly-titled question, there's a catch: in this case, you cannot use characters from the answer before ...
1
vote
3answers
320 views

Print the previous answer in reverse - with a catch [duplicate]

Your challenge is very simple: output the previous answer, in reverse. However, as with this similarly-titled question, there's a catch: in this case, you can only use characters from the answer ...
32
votes
8answers
6k views

Cut the gold chain

A traveler needs to stay for n days in a hotel outside town. He is out of cash and his credit card is expired. But he has a gold chain with n links. The rule in this hotel is that residents should ...
11
votes
21answers
1k views

An OEIS polyglot

This is an answer-chaining challenge relating to the OEIS. Oh, the justification for this is because a company needs one program to print out their OEIS sequences real bad and they have every ...
5
votes
2answers
263 views

Generate Aheui Number

Make a Number Expression is related : actually, it is also about Aheui. But it just made number expression, but this made real Aheui code. Aheui is esolang written in only Korean character. Because ...
10
votes
1answer
299 views

Self-displaying image [closed]

Background There are self-extracting .ZIP files. Typically they have the extension .EXE (and by executing the file they will be ...

1 2 3 4 5 17