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$N$ vessels initially contain $3$ stones each. What is the probability of having at least $3$ stones in the first vessel after moving a uniformly random selection from the first vessel to the secon...
In this challenge you will take an Irish word and a personal pronoun and create the possessive pronoun construction combining the two. For example sé, madra becomes a mhadra. Translated to English...
Given a string of Roman numerals, decide whether it forms a valid Roman number. If not, output the substring that proves this, from the list of 50 strings described below. Relevant fact This chal...
Your mission for today, should you choose to accept it, is to write a simple 12-hour clock calculator. Your input will always be in the form of arg op arg, where op is either + or -, and arg is eit...
You work in a kitchen which has a peculiar rule. When you mix something into a pot you must always add at least one new ingredient. So you can add pasta, oil, salt then pesto, but not pasta, pesto...
Goal Print the modular multiplicative inverse with a modulus of 65536 (or a higher exponent of 2) for odd numbers 1-97. Example output Print these values (or an extension of them): 1 43691 52...
This is a language specific challenge, for HTML only. Your answer is the content of a self contained HTML file, that when opened in a web browser gives a plain black page. Requirements The HTM...
Given a list of non-negative integers the function $f$ replaces every integer with the number of identical integers preceding it (not necessarily contiguously). So f [1,1,2,2,1,3,3] = [1,2,1,2,3,1...
The Universal Crossword has a set of guidelines for crossword puzzle submissions. In this challenge we are going to be concerned with their rules for hidden word themes. A hidden word clue consis...
You work at a beach. In the afternoon, the sun gets quite hot and beachgoers want to be shaded. So you put out umbrellas. When you put out umbrellas you want to shade the entire beach, with as few ...
Find the shortest representation of an integer in generalised Roman numerals. Since there is more than one way to generalise, only the following definition applies to this challenge. Definition T...
Given a single character, which is a valid Roman numeral, output its value. Values There are 7 valid single character Roman numerals, with the following values: Character Value I...
Given 3 positive integers, indicate whether they are Borromean coprimes. Definition 3 positive integers are called Borromean coprimes if both of the following are true: Their greatest common d...
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 $q$ outpu...
Input is a number, you have to decide if it is part of the mandelbrot set or not, after at least 16 iterations. This is done by applying this formula: $z_n = z_{n-1}^2 + c$ repeatedly. $c$ is the ...
Suggest a word from a word list, given a string. Motivation Imagine typing a word one letter at a time, and seeing a suggested word after each letter is typed. At first the suggested word is simp...
Recently I asked for tips on improving some code-golf of mine. The code was supposed to output every third value of the Fibonacci sequence starting with 2: 2,8,34,144,610,2584,10946,46368,196418,...
Simple challenge: Read a byte, swap bit 7 with 0, 6 with 1, 5 with 2 and 4 with 3 and then output the byte. For example the byte 0b1001'1100 would turn into 0b0011'1001. Rules: Shortest code wi...
import requests import json import numpy as np import base64 import cv2 Replace this with the actual image path you want to test image_path = 'H_L_.jpg' Read and preprocess the image image ...
At my job we have to sometimes lay out materials. Materials come in large long rolls and are cut into smaller pieces when being laid out. When we order the rolls we draw up a layout document which...
Given a number $n \geq 3$ as input output the smallest number $k$ such that the modular residues of $k$ by the first $n$ primes is exactly $\{-1,0,1\}$. That is there is a prime in the first $n$ p...
The probability of rolling every number from 1 to 6 with $N$ six-sided dice. Input A positive integer $N$. Your code must work for inputs up to and including 10, but may crash, error, or give ...
You roll $N$ six-sided dice simultaneously. Your score is the highest number rolled. If you play this game many times, what is the expected value (mean) of your score? Input A positive integer ...
Given two binary strings $A$ and $B$ such that $A$ is an anagram of $B$, output a third binary string $S$ such that both $A$ and $B$ can be created by iterated removals of the substring $10101$ fro...
Task You are going to take three strings as input $A$, $B$ and $X$. And your goal is to determine if there exists a third string $S$ such that both $A$ and $B$ can be formed by iteratively removin...
In this challenge you will take a number $n$ and a string $X$ of length $\geq n$, and produce a regular expression which matches all strings that are withing $n$ character substitutions of $X$. Sp...
You are a low-level censor working for the Ministry of Media Accuracy. Part of your job is to make sure that certain words don't appear in publications. Every morning you get a fresh stack of next...
Task Given a list of numbers $X$ produce a second list of numbers $Y$ such that $Y_i$ is the length of the longest common prefix of $X$ and $X$ with the first $i$ elements removed. For example if...
An polyomino is a non-empty connected subset of the square tiling consisting of squares joined along their edges. We will not require that polyominos be simply connected, that is they can have hole...
Given a hinged tetromino, give it a unique, consistent label independent of location, rotation, and reflection. Tetrominoes A tetromino is a connected subset of the square tiling, composed of 4 s...
An $n$-polyomino is a connected subset of the square tiling consisting of $n$ squares. We will not require that polyominos be simply connected, that is they can have holes. We will say a $n$-polyo...
The problem Someone has created an encoding format for square bit matrices, however they have found it isn't perfect! One encoding may not decode to exactly one matrix, or it may not even be possi...
Convert a matrix or grid of digits to its antitranspose. For a square matrix , this is its reflection in its antidiagonal. More generally, for a rectangular matrix, this is its reflection in its sk...
Given a string, convert all of its letters using ROT13, and all of its digits using ROT5. This is sometimes referred to as ROT13.5. Input A sequence of printable ASCII characters (character cod...
Given a sequence of lower case letters, sort them into order of height. Heights The heights of letters are dependent on font, so for this challenge the height order to be used is as defined below...
Connect opposite corners of a rectangle of characters without putting 4 characters in a row. Input Two numbers, W and H, representing the width and height of the rectangle Each number will be ...
Given a radius R, output a text representation of a circle. Input A positive integer R (strictly greater than zero) You do not need to handle values of R greater than 32 Output A square ...
Given a word that can be rotated by 180 degrees (a half turn) about at least one of its 3 axes and continue to be composed of English alphabet letters, output one of its rotated forms. The 3 rotat...
Given a string of printable ASCII characters, convert them all to lowercase, except not just the letters. ASCII characters that are letters have a bit in their binary representation that is 0 for ...
Given a sequence of letters, omit those with the highest or lowest pop count. Terminology The pop count or population count of a binary string is the number of 1s in it. For this challenge, the ...
Given a sequence of letters, output only the vowels. Input A sequence of letters This may be a string or any ordered data structure of characters (provided it is consistent between inputs) Th...
Given an integer $N$ in balanced quinary, output the first $N$ characters of your source code if $N$ is positive, or the last $-N$ characters of your source code if $N$ is negative. Terminology ...
Given a chess board with some knights on it, say how many squares are neither attacked by a knight nor containing a knight. Input An 8 by 8 grid where each square is either a knight or empty T...
Given a positive integer as input, indicate which base from 2 to 16 gives the most holes in the representation of the input in that base. The digits used are 0123456789ABCDEF. Note that these incl...
This is a fixed output challenge. Output a textual representation of a chessboard hosting 8 queens, none of which are attacking each other. There are 92 ways of arranging them, 12 if rotations and...
This is a fixed output challenge. It is similar to a standard Kolmogorov complexity challenge, except you get to choose your own fixed output. Given no input, output 55 fruits. You may choose any 5...
A chequer board (also spelt "checker board" in some places) is an 8 by 8 grid of squares alternating between 2 colours. Check whether a provided pattern could be a region of a chequer board. The c...
