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# Questions tagged [code-golf]

Code-golf is a competition to solve a particular problem in the fewest bytes of source code.

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### Count squares in my pi approximation

One way to approximate π is the following: Start by drawing a 2x2 square with a quarter-circle in it. Then, the area of the quarter-circle is π. We can approximate this area by filling it with ...
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### Smallest prime q such that concatenation (p+q)"q is a prime

Let p, q, and c := (p + q)"q (where " denotes concatenation) be positive integers such that p and c are primes and q is the smallest prime such that c is prime. Such a prime triple (p, q, (p ...
738 views

Here it is: ...
162 views

### Branchless median of 5

Write code to compute the median of 5 positive 32 bit integers. Your code must be branchless. A branch, jump or transfer is an instruction in a computer program that can cause a computer to begin ...
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### Convert base-10 to base-0.1

Base-0.1 mean e.g. 123.45 means in decimal $1\times 0.1^2+2\times 0.1^1+3\times 0.1^0+4\times 0.1^{-1}+5\times 0.1^{-2}$. Input and output should match RegEx <...
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### ASCII 2D landscape

You are given an input string, called path, consisting of u, d and s characters (i.e. ...
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### Function with memories of its past life

Task I need a function that accept string and return a function f1. That f1 function should also accept string and return a <...
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### I cant figure out how to make this python function shorter but I am convinced it is possible. Does anyone have any idea how I can achieve this? [closed]

Every time I dig too deep into this function I lose my trail of thought but I am almost certain it is possible to simplify. The code rotates points in 3 dimensions in my small project where I made a ...
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### Sylvester primes

Sylvester's sequence can be defined recursively S(n) = S(n-1)*(S(n-1) + 1) for n >= 1 starting S(0) = 1. Since S(n) and S(n) + 1 have no common divisors, it follows that S(n) has at least one more ...
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### Is it a date format of YYMMDD, MMDDYY, and/or DDMMYY?

The date format varies between countries; the arrangement of date, month and year can be categorized into these three: Year-month-date Month-date-year Date-month-year In Gregorian calendar it's year ...
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### How many ways can you make change?

The "third type of Euler Transform" takes an integer sequence that gives the number of objects of a given weight and outputs a sequences that gives the number of multisets of objects that ...
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### Snake a string through a simplex

An n-simplex is a generalization of 'triangleness' in any dimension (specifically, it is the simplest shape requiring n dimensions). Starting with 0 dimensions, the named simplexes are: point, line ...
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### Convert to Chomsky normal form

Let a context-free language be specified by its production rules and start symbol, e.g. S -> AbB | C C -> b | c B -> AA | AC A -> a | ε Here and in the ...
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### Encode a VarInt

Similar question to my previous one, but in reverse. This time I want you to encode an integer into a VarInt. Background: I'm not going to assume everyone's seen my previous question, so here is a ...
2k views

### Stuck on Sokoban

In the classic game of Sokoban the player's character solves puzzles by pushing boxes around a warehouse onto designated targets. Take, for example, this ASCIIfied game level: ...
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### Parse Minecraft's VarInt

If you look at the reverse-engineered Minecraft Java Edition server protocol, there is an interesting integer encoding method that is used quite often called VarInt. It works like this: You have an ...
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I have a friend with a peculiar habit (more, a long-running joke) of introducing everyone present at an event in this fashion: Alice, Bob. Bob, Tom. Tom, Bob. Bob... When there are more than a few ...
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### Function to Convert string to Hexadecimal [duplicate]

Assignment: Create a function that can convert a string to its encoded hexadecimal value. In your answer, also show how to run this function (to validate answers). Your function must return OR print ...
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544 views

### Curry a C function pointer [closed]

Objective Given a type signature of a C function pointer represented as a string, output the (fully) curried version of it, also as a string. I/O format It is assumed that: There is at least one ...
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### Calculate the sum of numbers in a rectangle

Aim Consider this infinite array of numbers: ...
647 views

### Miracle Miracle Octad Generator Generator

The Miracle Octad Generator (MOG) introduced by R. T. Curtis in 1976 is a central tool in the study of sporadic groups, error-correcting codes, Steiner systems, and sphere-packings. The MOG is ...
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### Ways to paint a backbone on a tree

Say I have some unlabelled tree graph: I'll define a "backbone" as a path on a graph that can't be extended - both its ends are at terminal vertices. There are three ways to overlay a ...
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### Erase the loops

A nice simple one! You are given a finite sequence. Find the earliest pair of equal elements, if any (where "earliest" refers to the position of the second element of the pair), and ...
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### Sum-of-four-squares grid

Output a grid of characters visualizing the decomposition of a number into a sum of four perfect squares. Challenge Given a nonnegative integer $0 \le n \le 2^{30}$, output a $2^k \times 2^k$ ...
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### Sums of X*Y chunks of the nonnegative integers

Consider the infinite table of the nonnegative integers with width 12: ...
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### Shift right by half a trit

Shift right by half a trit This is inspired by Shift right by half a bit, but it's a little different. Motivation I was wondering if there is a function f that maps ...
503 views

### Generalized Super-Luhn

Background Luhn's Algorithm is a simple check digit formula used to validate a variety of identification numbers. In standard Luhn, each second digit from the end is doubled, and then the digits of ...
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### Is there mutable aliasing in this list of variable references?

Rust's borrow checker enforces the requirement of "mutability XOR aliasing": a piece of data can either have multiple immutable references or a single mutable reference. This challenge ...
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### Make a GCSE student's error work

A GCSE computer science student recently made this hilarious blunder on their exam and posted it online. Now, you must make it work: ...
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### Do something you can't do in Brainfuck [closed]

Goal Do some action (like delete a file, connect to a server, …) that you can not do in standard Brainfuck. What As you know, all calculations you can do in almost any programming language you can ...
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### Cubic Concatenation

Challenge Given three non-negative integers $a, b$ and $c$, decide if the sum of their cubes is equal to the concatenation of those numbers, aka: $$a^{3}+b^{3}+c^{3} = a^\frown b ^\frown c$$ ...
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### Lexicographically earliest permutation of the initial segment of nonnegative integers subject to divisibility constraints

The challenge is simple: Reorder the first integers {0, 1, 2, ..., n} into an ordered list so that the following three conditions are met: If k is the last element in the list, then all of its prime ...
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### Is this a valid Irish word?

In Irish, most consonants are divided into broad (velarized) and slender (palatalized) variants, and the orthography marks them with neighboring vowels, which are similarly divided. This gives rise to ...
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### Counterexample to Shapiro inequality

Input: A positive integer n such that n is even and greater than 12 or n is odd and greater than 23. Output: A list of non-negative integers that violates Shapiro inequality. More precisely, Let s be ...
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### Automatic Pikmin Count

Inspired by the feature in Pikmin 4. In Pikmin 4, you can have up to eight types of pikmin in an onion and up to three types of pikmin outside the onion. Each area recommends three types of pikmin to ...
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### Rabinowitz-Wagon $\pi$ formula

In 1995, Stanley Rabinowitz and Stan Wagon found an interesting algorithm to generate the digits of $\pi$ one by one without storing the previous results. The algorithm is called the spigot ...
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### Three up to 800 & sum to 2048

(Flexibly) output 3 random integers such that: Each number is 1 to 800 inclusive Their sum is ...
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Given a finite sequence, each of its elements has a first occurrence. Your task is to output the symbol whose first occurrence is last in the sequence. If the elements represent posts and reposts of ...
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### Reduce a string up to idempotency [closed]

Objective Given a string consisting of printable ASCII characters (!0x21 ― ~0x7E), treat it as an element in the free idempotent ...
• 6,299
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### How comparison-heavy is this list? [closed]

Given a list of strings in any convenient format display the amount of comparisons between individual characters that a merge sort algorithm would perform. The merge-sort algorithm is a divide & ...
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### Double dequer sort

In this challenge Bubbler describes sorting a list by inserting its elements left to right into a double ended queue or "deque". Take a number from the front of the array, and push it into ...
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### GolfScript many-items rotation

There isn't a builtin in golfscript which lets you rotate a bigger portion of the stack than the three top-most elements. It should take one number n as argument and rotate the nth value from the top, ...
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### Substring of Fizzbuzz

Decide if a string is substring of Fizzbuzz without separation 12Fizz4BuzzFizz78FizzBuzz11Fizz1314FizzBuzz.... Notice that it doesn't necessary cover whole tokens, ...
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### Simulate Text Cursor

You are given a string [A-Za-z|]+ that contains exactly one occurrence of | denoting the current position of the cursor and a ...
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### Braille-based Base64

Make a one-to-one map from the base64 character table(0-9a-zA-Z+/) to Braille(U+2800-U+283F). These characters are fixed map for compatibility. For other characters(aka. A-Z and +) you can map any ...
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240 views

### Shortest way to cause a seg fault at 0x9c?

In honour of CrowdStrike's exception at 0x9c, what's the shortest way (character-wise) to cause a segfault by dereferencing address 0x9c? The best I can come up with is: ...
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### Compute Dickman

Input A floating point number $x$ between 1 and 8 inclusive. Output The Dickman function of $x$. The Dickman–de Bruijn function $\rho(u)$ is a continuous function that satisfies the delay ...
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### Check if two lists are permutations of each other [duplicate]

Challenge Given two lists of equal length, find if one of them is a permutation of the other. Output truthy or falsy values, or 1 or 0. Test case Examples ...
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Given a multiset of integers, order them such that the largest absolute prefix sum $$\max_i \left| \sum_{k<i} a_k \right|$$ is smallest. Output any solution if multiple exist. You can assume input ...