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# Questions tagged [sorting]

This challenge is intended to be solved by sorting, ordering, or otherwise organizing some set of data.

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### North Korean dictionary order

The objective Given a string of Hangul syllables, sort the characters in North Korean dictionary order. Introduction to Hangul syllables Hangul(한글) is the Korean writing system invented by Sejong ...
8k views

### Sort a list and write some English!

Your boss managed to read the secret hidden message. He didn't end up firing you, though, he just made you a secretary and forbade you from writing code. But you're a programmer. You need to write ...
5k views

### Sort odd numbers first

Rearrange a given list such that all the odd numbers appear before all the even numbers. Besides for this requirement, the output list may be in any order. The input will only contain integers, but ...
2k views

### Enumerate each series of identical numbers in-place

Given a list of strictly positive integers, go through each distinct number and replace all occurrences of it with successive indices (zero or one based) of a new series. Examples ...
25k views

### Implement the Thanos sorting algorithm

The sorting algorithm goes like this: While the list is not sorted, snap half of all items (remove them from the list). Continue until the list is sorted or only one item remains (which is sorted by ...
691 views

Someone has been hastily stacking the Christmas presents, and it's quite a mess: ...
2k views

### Sort the months of the year

Write a function or program that takes string inputs, fully-spelled, English month names in title case: January, February, ...
8k views

### Lossy Sorting (Implement Dropsort)

Dropsort, designed by David Morgan-Mar, is an example of a linear-time "sorting algorithm" that produces a list that is, in fact, sorted, but contains only some of the original elements. Any element ...
196 views

### Dropsort with a Twist

This is my first attempt at a Code Golf question. If it needs obvious edits, please feel free to make them. Below is a description of the basic Dropsort algorithm. Dropsort is run on a list of ...
2k views

### Tell me how to flop

As computer scientists, you're probably all familiar with the basic list operations of pop and push. These are simple operations that modify a list of elements. However, have you ever heard of the ...
849 views

### Let's practice the scoring rules of 421!

421 is a rather popular dice game in France and some other European countries. It is mostly played in bars and pubs to determine who's going to buy the next round of drinks. The full game is usually ...
427 views

### Pseudosort a list in 2*n comparisons

Write a program that takes a list of n space-separated integers, and outputs a permutation of that list using a maximum of 2*n comparisons. It should loop this until an empty line is input. ...
3k views

### A quine of sorts

Given a string x, output the characters in x sorted according to the order of appearance in your source code. Examples ...
347 views

### Write the shortest O(n^2) sorting algorithm [closed]

Write a sorting algorithm for a list of integers that has an average performance of O(n^2). This is code-golf, so the shortest code in bytes wins. RULES: The characters wasted for the declaration ...
2k views

### Block-sorting rows and columns in a 2D array

Given a 2D array of integers, let's sort its rows and columns in blocks. This means that you only have to sort a given row or column, but applying the transformations needed for sorting it to every ...
2k views

### Rotated Position of Integers

Challenge: Input: A sorted list of positive integers. Output: The amount of integers which are still at the exact same index, after rotating the digits in each integer its index amount of times ...
816 views

### Sort a list of numbers on the λ-calculus

Write a term on the pure untyped lambda calculus that, when applied to a church-encoded list of numbers, returns it with its numbers sorted in ascending or descending order. Church lists and numbers ...
1k views

### Sort of numbers

Within the recesses of Unicode characters, there exists a Unicode block of (currently) 63 characters named "Number Forms", which consists of characters that have numerical values such as the roman ...
4k views

### Arrow those variables!

Challenge Robin likes having his variables declaration in the shape of an arrow. Here's how he does it: Input any number of strings Order them by ascending length Output them ordered by the middle ...
2k views

### Rearrange a number into alphabetical order

Given a non-negative integer (n), create a function that returns n in alphabetical order, according to the literal spelling of ...
1k views

### The Strange Unsorting Machine for Nefarious Purposes

Good Evening Golfers! Your challenge is to completely unsort a series of numbers. Input Exactly 100 integers will be fed to your program. Your program may accept the input either as a file, or via ...
400 views

### Matrix rotation sort

Lets define a non-empty, unsorted and finite matrix with unique numbers as follow: $$N = \begin{Bmatrix} 4&5&7\\1&3&6 \end{Bmatrix}$$ Lets define 4 matrix moves as: ↑* (up): Moves a ...
2k views

### Implement Bogosort

Is solving Sudoku too hard? Even the brute force version? Here's a coding exercise that's a little easier. I hope. :-P Write the shortest function to implement bogosort. In specific, your function ...
4k views

### A “Sorting” algorithm

There is a "sorting algorithm" sometimes called Stalin sort in which in order to sort a list you simply remove elements from the list until it is sorted in increasing order. For example the list <...
2k views

### Count My Change

Your task is to sort an array containing the strings "quarter", "dime", "nickel", and "penny" any number of times in no specific order and sort them so that they are in this order: ...
4k views

### Sort an Integer List

The Challenge It's quite simple really, sort a list of numbers. Details You must sort a list of numbers in ascending order, without using any built-in sorting functions/libraries/etc (i.e. ...
287 views

### Sort a list without builtin functions

Sorting a list would make a pretty fun code-golf challenge, but all the builtins make it boring! Its no fun when you spend all of your time golfing a function and then you see that someone else has a ...
4k views

### Vertically collapse text

Say I have text like this (each word on one line, with no spaces) Programming Puzzles & Code Golf That makes no sense! It totally defies the laws of physics. ...
7k views

### Find the longest word in an array

Your challenge is to take an array of strings and output the longest string in the array. So for ["tiny", "small", "bigger", "biggest"] the output would be ...
185 views

Christmas is coming up, and this year you have been charged with organizing your family's christmas get-together. You have a list of foods you want be there, but before you assign foods to people, you ...
2k views

### Sort by Largest Digit(s)

Challenge: Given a list of integer, sort descending by their single largest digit(s). The order for numbers with the same largest digit are then sorted by second largest digit, etc. We ignore ...
15k views

### Sort numbers by binary 1's count

Goal Write a function or program sort an array of integers in descending order by the number of 1's present in their binary representation. No secondary sort condition is necessary. Example sorted ...
131 views

### StalinSort Golf [duplicate]

Someone sent me this description of a joke sorting algorithm, and I thought it would make for a fun golf. Given a list of positive integers remove all elements that aren't larger than all elements ...
2k views

### Blind Random Sort

Here's a pretty common pattern for sorting algorithms: ...
5k views

### PronunciationSort™

We all know of different fancy sorting algorithms, but none of these give us numbers in a way that's easy to pronounce. To remedy this, I propose using PronunciationSort™, the most natural way to sort ...
515 views

### Rubik-sorting a matrix (a.k.a. the torus puzzle)

The idea for this code-challenge is simple: given a matrix of integers, let's sort it by applying Rubik-style movements. This means that you can select a single row or column and rotate its elements ...
327 views

Sometimes lexicographical sorting of strings may cut it, but when browsing the filesystem, you really need better sorting criteria than just ASCII indices all the time. For this challenge, given a ...
2k views

### Indentation-based Sort

Given an ordered list of same-case letter strings (a-z XOR A-Z) where each string is preceded by 0 or more space ( ) characters, output the same list but with the strings sorted at each level of ...
478 views

### Codegolf Rainbow : Sorting Colors with Reflection

Introduction: After I posted two rainbow-related challenges: Codegolf Rainbow : Fun with Integer-Arrays 1 and Codegolf Rainbow : Draw in Black-and-White 2, the following comment was made by @ChrisM ...
2k views

### Sort by what the digit pairs describe

Given a positive integer, we can form a new number that's described by its digits taken pairwise (with a leading 0 added for numbers with odd number of digits). For eg.: 1234 can be read as one 2, ...
2k views

### Ordering a list

Summary Given a list of integers, return the index each integer would end up at when sorted. For example, if the list was [0,8,-1,5,8], you should return ...
3k views

### There are two new sheriffs in town – Identifying DJMcMego pairs!

We have some new sheriffs moderators in town, Mego and DJMcMayhem. We need a challenge to properly honour them for their new positions, so there we go. Here's something that has caught my attention ...
383 views

### Einstein's Sorter

Challenge Given a list of integers and a velocity, $v$, implement a sorting algorithm which simulates a program sorting the list from smallest to biggest at the given velocity. Einstein's Theory ...
430 views

### Help me fill my wallet!

A while ago I purchased a new wallet which is able to hold 8 cards (4 on both side). However, I seem to have way more cards than that and I need to make choices on which ones I want to carry with me. ...
4k views

### The Rien Number

The Champernowne constant is a number that is constructed by concatenating the first n numbers, with n tending to infinity. It ...
326 views

### Pair and sort from two integer lists

You are given two arbitrary integer lists, e.g. [-10, 99, -6, 43], [100, 32, 44]. You are to pick one integer from each list and ...
892 views

### Optimize sorting, using “Sub-vector reversals”

This is a fewest-operations challenge where the objective is to sort a vector into ascending order using the fewest reversals. Your algorithm can only sort the vector using "sub-vector reversals"1, ...
16k views

### Sorting a list of strings without using any built-in sort method

The goal of this Code Golf is to create a program that sorts a list of strings (in ascending order), without using any built-in sort method (such as Array.Sort() in ...