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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Writing Phrases with Code

This is my first contest, so please tell me what I can do to improve. The object of this contest is to write program lines in your language of choice that are both valid code and self-descriptive in ...
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0answers
92 views

Frogger Champion

The Game Most of us know about Frogger, the 80's era arcade game where the objective is to hop a frog safely across a busy highway and a hazard-filled pond to arrive safely at home. A challenge was ...
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2answers
384 views

Rolling digital number lock [duplicate]

There's a simple digital number lock. After each button press the lock checks if the previous four presses constitute the correct code. I.e. typing 44445 tests two codes: 4444 and 4445. You must brute ...
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7answers
1k views

The Bowlers-Golfers Fraction War

Introduction Let's start by arranging all fractions from 0 to 1 in order of lowest denominator, then lowest numerator: 1/2, 1/3, 2/3, 1/4, 3/4, 1/5, 2/5, 3/5, 4/5, 1/6, 5/6, 1/7... Note that ...
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3answers
417 views

Sort some apples!

Problem Imagine 7 buckets lined up in a row. Each bucket can contain at most 2 apples. There are 13 apples labeled 1 through 13. They are distributed among the 7 buckets. For example, {5,4}, {8,10}, ...
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5answers
2k views

Radioactive Quines

A radioactive quine is a quine-like program that has an even number of characters and, when run, outputs itself with exactly half of its characters removed. The output itself may be a radioactive ...
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0answers
214 views

Detect Duplicate Questions

Detect Duplicate Questions Once upon a time, there was a golfing site. It had a problem: people would post similar or identical questions again and again. You have been chosen selected forced ...
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3answers
698 views
+50

Restricted memory optimization

The edit (or Levenshtein) distance between two strings is the minimal number of single character insertions, deletions and substitutions needed to transform one string into the other. If the two ...
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2answers
117 views

SPCL (Society for the Prevention of Cruelty to Loopholes) [closed]

I am a founder member of the above society. Maybe that's why people keep telling me I'm special. I want to raise the profile of loopholes. I am looking for a program which exhibits as many ...
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10answers
1k views

How to slow down a drunkard on his way home

Consider a square n by n grid graph that looks like this. It is important to notice that this graph is 11 by 11. At any given point a man stands at an intersection and he only ever moves ...
10
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0answers
253 views

How long is your (language) snake?

Following on from the third order quine challenge, your task is to write an Ouroboros program that uses as many languages as possible. That is, in language A, write a program pA which outputs program ...
6
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4answers
1k views

Can you beat the optimizer?

This is an optimization/algorithms challenge. Given two sets of points X and Y, which are to be thought of as points on a circle of circumference T, the challenge is to find the rotation which ...
33
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23answers
5k views

Rosetta Stone Challenge: What's Average Anyways?

The goal of a Rosetta Stone Challenge is to write solutions in as many languages as possible. Show off your programming multilingualism! The Challenge When people use the term "average," they ...
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0answers
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Find if all brace pairs in an array of strings are correctly formatted [duplicate]

I created a fun challenge. I call this the BRACES Challenge. The rules are simple. Given an array of strings, find out if all brace pairs in each string are formatted correctly. braces: []{}() ...
44
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17answers
5k views

mastermind horse battery staple

Objective Given a list of three-word passphrases, crack them all. Each time you guess, you will be given a clue in the style of Mastermind, depicting how many characters match the password, and how ...
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3answers
789 views

Another Euler Brick in the Wall

A Euler Brick is a cuboid where the length of all the edges are integers and all of the diagonals of the faces are integers as well. All sides must also be different. Your program has to find as ...
21
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1answer
1k views

Domino Circuits

Scoreboard Here are the raw scores (i.e. domino counts) for VisualMelon's submission. I'll turn these into the normalised scores described below, when more answers come in. The existing solution can ...
16
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1answer
569 views

Horror Movie Search Party

Plot: Jimmy is missing; we have to find him. We should split up. Plot twist: Jimmy is already dead. But, our cast doesn't know that, so they need to search the whole area anyway. There is an N ...
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1answer
205 views

fit 22 (perhaps 23) of a specific 3d pentacube into a 5x5 cube

The original problem is stated here over at math.SE The task is writing a program that fits 22 copies (or perhaps 23) of the following pentacube into a 5x5x5 cube (back and front view). The ...
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6answers
1k views

ASCII Art Calendar

Let's make an ASCII art clock and calendar that tells us the current month, day of the month, day of the week, hour, minute, and whether it's night or day (but not the year or second). At any ...
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5answers
948 views

Find the craftiest prime

Intro Consider the process of taking some positive integer n in some base b and replacing each digit with its representation in the base of the digit to the right. If the digit to the right is a 0, ...
30
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14answers
7k views

Programming Dichotomies (Literally)

Consider a question written in plain English whose answer involves two reasonably accurate (but potentially clever) words or phrases that can be separated by the word 'and': Q: What are the two ...
12
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1answer
415 views

Fusing Fireworks

Overview Given a list of fireworks a-z and times 3-78, arrange them with fuses to make them all light up at the correct time. A line of input is given as space separated letters and numbers: a 3 b ...
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15answers
5k views

Implement the Game of Life on anything but a regular grid

Conway's Game of Life is (almost) always played on a regular square grid, but it doesn't need to be. Write a program that implements the standard cell neighboring rules from Conway's Game of Life on ...
37
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12answers
6k views

What's the shortest contiguous subset of ASCII you need to output the rest?

The printable ASCII characters (hex codes 20 to 7E) in order are: !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~ (Note that space is in ...
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1answer
197 views

Minimal cover of bases for quadratic residue testing of squareness

Challenge Find the smallest cover of bases (e.g., moduli) whose sets of quadratic residue can be tested via table-lookup to definitively determine whether or not a given non-negative integer n is a ...
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6answers
317 views

sort and restore a set of bytes in optimal form

Challenge For any given input Y of length >= 1024 bytes: sort in ascending or descending order -- your choice generate output Q, where Q = [sorted data] + [restore information] restore Y using Q as ...
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3answers
528 views

Find the shortest bracket numbers

Bracket numbers provide a simple way to express large integers using only left bracket, space, and right bracket ([ ]). A bracket number is defined as a string of one or more pairs of matching ...
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2answers
269 views

Find prime which is generating longest primes sequence using p(n+1)=(p(n)^2+1)/2

Consider following recurrence relation: p[n + 1] = (p[n]^2 + 1) / 2 If p[1], p[2], ..., p[k] are primes and p[k+1] is not, then k is length of sequence starting with p[1]. For example, if p[1] = 3, ...
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10answers
4k views

Find the largest prime whose length, sum and product is prime

The number 113 is the first prime whose length 3 is prime, digital sum 5 = 1 + 1 + 3 is prime, and digital product 3 = 1 * 1 * 3 is prime. A prime that has these 3 properties will be called supremely ...
22
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3answers
959 views

Where are the runs in this infinite string? (CCCCCC Found!)

Starting with the string ABC, consider the result of repeatedly appending the last half of itself to itself (using the larger half if the length is odd). We get the progression: ABC ABCBC ABCBCCBC ...
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13answers
1k views

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: ...
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2answers
399 views

Conway's Game of Life with smallest *set* of source characters [duplicate]

The goal of this challenge is to write a program that will simulate a single round of Conway's Game of Life on an existing grid. Input format: Input will be read from stdin. The input will consist ...
14
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2answers
513 views

Maximum number of PEP8 violations in a single line

Your task is to write a file which contains a line with many pep8 violations. The rules: We use pep8 version 1.5.7 and the default settings. Calling pep8 with other command line options or ...
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1answer
305 views

Make a Number Expression

Few years ago, an esoteric programming language named 아희(Aheui) was created. Well, actually you don't need to know about this language or Korean characters. Aheui uses stacks and a queue, but this ...
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2answers
1k views

Optimize paper folding to mitigate inkblots

Dark black ink has splattered all over your white sheet of printer paper! The obvious solution is to fold the paper so black and white parts meet and both become grey as the ink diffuses. Then unfold ...
3
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1answer
1k views

Optimal Minesweeper on the Largest Board

Overview: Your challenge is to write a program that will play minesweeper optimally, giving the best move in any position. Moreover, you must do this on the largest board possible. Game details: ...
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1answer
350 views

Babylon.js - loop through a scene and apply a simple fragment shader to all of the objects

You have a library - a fully loaded 2014 Babylon.js. You have a fragment shader - let's call it sample.fragment.fx. You have a scene - loaded ahead of time, possibly from a .babylon JSON file. Your ...
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3answers
449 views

mathpack numeric literals

preface In a very heated situation you have to go even further with golfing. (e.g. in a challenge where your answer is 100 characters long and it is just embarrassing that you couldn't make it 99) ...
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4answers
594 views

Rotate 2D Array [duplicate]

Given an input of a 2 dimensional array of integers, rotate the array 90 degrees clockwise. It should work for rectangular arrays of all sizes and proportions. The rotated array should be printed at ...
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1answer
423 views

Racketeer Taxi Driver

The Scenario You are a taxi driver in your city. You picked up a passenger from the airport and he told you the place he'd like to go. To earn more money, you need to drive as much as you can. ...
29
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6answers
3k views

To Vectory! – The Vector Racing Grand Prix

Vector racing is an addictive game that can be played with a pen and a sheet of square-ruled paper. You draw an arbitrary racetrack on the paper, define a start and end and then you steer your ...
3
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2answers
383 views

Deplane! Deplane! (Or: RGBRGBRGB => RRRGGGBBB?)

Imagine bytes in memory for an RGB image--R and G and B represented by bytes in sequence. If an image is NxM then the memory layout will be M repetitions for vertical scanlines of 3*N bytes in ...
18
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2answers
1k views

Mastermind strategy

I could only find code-golf challenges for Mastermind, so here's a code-challenge version that I would have liked to take on myself. An optimal strategy for the normal Mastermind game, MM(4,6), was ...
11
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2answers
504 views

Travelling Salesman

Your are given, as a list or vector or whatever, a bunch of 3-tuples or whatever, where the first two things are strings, and the third thing is a number. The strings are cities, and the number is ...
56
votes
41answers
9k views

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. ...
20
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3answers
911 views

Build a pair of spies that will throw stones into a river

Recently at the newly released Puzzling.SE, there was a problem about spies throwing stones into a river that was actually quite challenging: Two spies must pass each other two secret numbers (one ...
10
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0answers
613 views

Efficient error-free* encoding

The mission As is well known, the genetic material of all known creatures on Earth is encoded in DNA; using the four nucleotides adenine, thymine, cytosine, and guanine. (Commonly represented by ...
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3answers
2k views

Fastest player for Dots and Boxes

The challenge is to write a solver for the classic pencil and paper game Dots and Boxes . Your code should take two integers m and n as input which specifies the size of the board. Starting ...
18
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5answers
1k views

Leet to English Translation

Leet to English Translation Your challenge is to write a program to translate (English) leetspeak/lolspeak/txtspk into normal English. Your program should read from standard input and output to ...