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28
votes
30answers
3k views

Smallest number such that concatenation is a square

Challenge Write a program or function that takes a number \$n\$ and returns the smallest \$k\$ such that concatenation \$n'k\$ is a square. This sequence is described by A071176 on the OEIS. I/O ...
5
votes
9answers
324 views

Elastic collisions between blocks

The 3Blue1Brown Youtube channel released a video a year ago called "Why do colliding blocks compute pi?" which describes a model where a block A of mass \$a\$ ...
-11
votes
21answers
391 views

Sequence and Series

Use any programming language to display numbers divisible by 1000000 that are greater than 1 and less than 10000000. Each number should be displayed in new line. Your program should display exactly: <...
9
votes
8answers
834 views

The longest period iterating quine

As we know, a quine is a program that outputs its own source code. However, it's also possible to write a program that outputs another, different program, that outputs the first program again. For ...
114
votes
56answers
26k views

GO OUT AND VOTE

Today is November 8th, 2016, Election Day in the United States of America. If you are a U.S. citizen eligible to vote, then go out and vote if you haven't already before answering this challenge. Do ...
16
votes
7answers
2k views

Narcissistic Quine

Write a program/method that: Becomes a quine when the input matches the source code; Doesn't halt otherwise. This is code-golf, so shortest solution wins. Avoid any standard loopholes.
6
votes
2answers
202 views

Minigolf Solitaire

Inspired by a question on the puzzling stack exchange. Rules Given 5 stacks of 5 cards numbered 1 to 7, output the moves needed to empty all stacks. A move is defined as the index of a column to ...
19
votes
41answers
4k views

Make me a s'more!

Make me a s'more! I tell you the width, the amount of graham cracker, the amount of chocolate, and the amount of marshmallow. An example: Input: Width: 10 Graham: ...
-3
votes
3answers
152 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\$. ...
36
votes
9answers
3k views

Simple Circular Words

A "simple circular" word is a word whose chords do not intersect. The chords of a word may be seen by laying out the alphabet in a circle, and then connecting the word's consecutive letters. ...
86
votes
277answers
22k views

Print a 10 by 10 grid of asterisks

Background This is a standard textbook example to demonstrate for loops. This is one of the first programs I learned when I started learning programming ~10 years ago. Task You are to print this ...
16
votes
69answers
7k views

Swapping “Good” and “Bad”

Challenge Description: Write a program that asks the user for input. The user will enter Good or Bad. You do not have to ...
22
votes
84answers
6k views

Make me a square!

Task Given one non-whitespace printable character, make a 3x3 square representation of that input. For example, if the input is #, then the output is: ...
18
votes
21answers
5k views

Largest monetary amount impossible to make with two types of coin

Suppose we have two different types of coin which are worth relatively prime positive integer amounts. In this case, it is possible to make change for all but finitely many quantities. Your job is to ...
152
votes
275answers
42k views

1, 2, Fizz, 4, Buzz

Introduction In our recent effort to collect catalogues of shortest solutions for standard programming exercises, here is PPCG's first ever vanilla FizzBuzz challenge. If you wish to see other ...
34
votes
53answers
5k views

ROT-13 transform standard input

The challenge: To read an input of arbitrary length and produce the ROT13 of the input. All characters besides A-Z should be copied to the output verbatim, and case should be preserved if possible. ...
17
votes
14answers
1k views

Bucket and Minimize

The challenge - given a numeric list L and an integer N as inputs, write a function that: finds the bucket sizes for L such that it is split into N whole buckets of equal or near-equal size, and ...
26
votes
54answers
3k views

Orthodiagonal steps

It's a common problem to navigate in a 2D matrix. We've seen it many times and will see again. So let's help future us and develop the shortest solutions to generate all eight possible steps in a 2D ...
17
votes
8answers
2k views

Write the longest period iterating quine bounded by 500 bytes

Your job is to create the longest period iterating quine, where the length of each program in the sequence is bounded by 500 bytes. That is, if you repeat the following steps: Start with your ...
59
votes
19answers
5k views

Tips for golfing in R

I'm looking for tips for golfing in the R statistical language. R is perhaps an unconventional choice for Golf. However, it does certain things very compactly (sequences, randomness, vectors, and ...
17
votes
8answers
644 views

Counts Of Orderings Containing At Most K Of The Kth Class

This challenge is about the number of orderings which contain at most \$n\$ classes and at most \$k\$ of the \$k^{\text{th}}\$ class. One way to represent such an ordering is as a sequence of ...
15
votes
18answers
2k views

Super permutations

Super permutations Input: A string The program should loop through all lengths of the input (decrementing one each time), generate all combinations with replacement of the string, then make ...
31
votes
35answers
5k views

Shift right by half a bit

The challenge is to implement a program or function (subsequently referred to as "program") that takes a nonnegative integer \$n\$ as input and returns \$n\over\sqrt{2}\$ (the input divided by the ...
20
votes
13answers
2k views

Check if all non-zero elements in a matrix are connected

Input: A matrix containing integers in the range [0 - 9]. Challenge: Determine if all non-zero elements are connected to each other vertically and/or horizontally. Output: A truthy value if all ...
22
votes
3answers
1k views

Map of Islands (and a river)

Introduction For many centuries, there has been a certain river that has never been mapped. The Guild of Cartographers want to produce a map of the river, however, they have never managed to succeed -...
18
votes
3answers
890 views

Draw 'Til You Drop

In Dungeons & Dragons 5th edition (as well as most other editions), there exists a magic item called the Deck of Many Things. It is an incredibly powerful item, as the cards all have very strong ...
24
votes
16answers
2k views

Draw ASCII boxes in boxes

Problem given input a,b,c where a,b,c are positive even integers and a > b > c ...
19
votes
5answers
576 views
+200

Singly lossy integers: Concatenated sequences missing a single element

I define the method of combining a sequence to mean that every number in the sequence is concatenated as a string, then that result is made an integer. ...
20
votes
20answers
3k views

Draw a big ASCII X

Problem Inspired by a previous challenge doing something similar Given positive integer input n output a shape that follows this pattern: input ...
33
votes
8answers
2k views

Newtons Method by Recursive Quines

Your task is to calculate the square root of 2 using Newton's Method - with a slight twist. Your program is to calculate an iteration using Newton's Method, and output the source code for the ...
59
votes
39answers
4k views

Write the shortest self-identifying program (a quine variant)

Write a program that will generate a "true" output iff the input matches the source code of the program, and which generates a "false" output iff the input does not match the source code of the ...
27
votes
10answers
6k views

Write a program that sees the New Year in itself

Write the smallest program that maps strings injectively to outputs and maps itself to 2020. To be clear, your program \$p\$ must have the following properties: every possible input string \$s\$ has ...
204
votes
340answers
46k views

Golf you a quine for great good!

Using your language of choice, golf a quine. A quine is a non-empty computer program which takes no input and produces a copy of its own source code as its only output. No cheating -- that means ...
30
votes
46answers
5k views

Russian Roulette

Write a program which plays Russian Roulette! If the program is started, there should be a 5 in 6 chance of it ending normally after printing "I survived!" there should be a 1 in 6 chance of the ...
31
votes
23answers
3k views

Make it rain characters

Inspired by this chat mini-challenge. Given a string as input (ASCII printable characters only), output the string with the letters "raining" down. Each letter must be a random number of lines ...
15
votes
13answers
1k views

Quoting Big Brother

Task: Have your program randomly choose one of the following two quotes at runtime and print that one quote, exactly as shown. 1: ...
4
votes
3answers
364 views

Minified Intcode Computer

As the trip through the solar system on your way to rescue Santa gets a little droll, so perhaps some optimizations to your Intcode Computer are in order. Namely, making it as small as possible ...
23
votes
46answers
5k views

Internal Truth Machine

It's a normal truth machine but instead of taking input, it uses the first character of the program. Thus, internal. The 0 and 1 are plain characters, i.e. ASCII code 0x30 and 0x31 respectively. ...
12
votes
7answers
479 views

Make a random drum loop

Do randomly generated drum loops sound good? A drum loop is a \$5\times 32\$ matrix \$A\$ of \$1\$s and \$0\$s such that \$A_{1,1}=A_{1,17}=A_{2,9}=A_{2,25}=1\$, for each \$i\$, the \$i\$th row has ...
-8
votes
0answers
58 views

How to run the 2019 IOI test cases against my solution? [closed]

The question and solutions are available here: https://ioinformatics.org/page/ioi-2019/51 There's a folder containing "MakeFile" for tests, I do not know what to do with it. Can someone please help ...
5
votes
4answers
829 views

Quit Whining; Start Quining

Goal: Write a function or program that, given an integer n, will output a program in the same language that is a quine with a period of ...
27
votes
38answers
3k views

The plus-minus sequence

The plus-minus sequence The plus-minus sequence is one that starts with two seeds, a(0) and b(0). Each iteration of this ...
200
votes
296answers
46k views

Is this number a prime?

Believe it or not, we do not yet have a code golf challenge for a simple primality test. While it may not be the most interesting challenge, particularly for "usual" languages, it can be nontrivial in ...
-5
votes
0answers
91 views

Tetris Game in C challenge (Strictly in C) [closed]

The challenge is to show your game written in the Mother of all programming languages, i.e. C. Criteria: A reasonable scoring system must be in place, which rewards multi-line clears more than single-...
16
votes
18answers
2k views

Simplification of numbers

How, you can’t remember the 6 or 7-digit phone number that appeared on the TV screen for a second?! Using the special technique described below, you will turn into a walking phonebook! Obviously, the ...
68
votes
145answers
7k views

Output the sign

Given a number N, output the sign of N: If N is positive, output 1 If N is negative, output -1 If N is 0, output 0 N will be an integer within the representable range of integers in your chosen ...
35
votes
32answers
5k views

Make it explode!

Take a matrix of positive integers as input, and make it explode! The way you explode a matrix is by simply adding zeros around every element, including the outside borders. Input/output formats are ...
40
votes
85answers
4k views

Product over a range

Your task is simple: given two integers a and b, output ∏[a,b]; that is, the product of the ...
429
votes
771answers
132k views

“Hello, World!”

So... uh... this is a bit embarrassing. But we don't have a plain "Hello, World!" challenge yet (despite having 35 variants tagged with hello-world, and counting). While this is not the most ...
27
votes
39answers
2k views

Subtract the next numbers

Description Subtract the next P numbers from a N number. The next number of N is N + 1. Look at the examples to get what I mean. Examples: ...

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