# Questions tagged [sorting]

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

59 questions
7k 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 ...
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### Flipping pancakes

In pancake sorting the only allowed operation is to reverse the elements of some prefix of the sequence. Or, think of a stack of pancakes: We insert a spatula somewhere in the stack and flip all the ...
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### 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. ...
857 views

### Code Golf: Mix the nuts so that none of the same kind are touching

Input: Input is a randomized array of nuts (in your language), the possible nuts follow. Your program must have a way of representing each kind of nut, such as an integer code. Program must be able ...
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### Implement a sorting algorithm with no change. [closed]

In this task, you have to write a program, that reads a string with a length of up to 1024 characters and prints it out sorted. In order to make an interesting task from a boring one, I set a few ...
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### 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 ...
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### Implement QuickSort in BrainF*** [closed]

As discussed in the Lounge room on Stack Overflow: if you can't implement the Quicksort algorithm given en.wikipedia.org/wiki/Quicksort in any language you have minimal knowledge of, you might want ...
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### 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 ...
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### 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 ...
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### Imitate an ordering

Given two lists of numbers, a source and a pattern, reorder the source to match the relative ordering of the pattern. Any two entries of the reordered source should compare the same way as the entries ...
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### Bubble sorting in progress

Create a function or program that takes two inputs: A list of integers that shall be sorted (less than 20 elements) A positive integer, N, saying how many ...
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### City names game

If you like, write a program which sorts cities according to the rules of city name game. Each name of the city should start from the last letter in the previous city name. E.g. ...
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### Xorting an array

Conceptually, this challenge is really simple. You're given a list of non-negative integers ai. If possible, find a non-negative integer ...
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### 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. ...
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### Sort a list of numbers [closed]

About Code-Bowling: In golf, you try to get the lowest score (smallest application, most elegant, etc). In Bowling, you try to get the highest score. So if you follow, the goal of a Code-Bowling ...
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### Sign that word!

What is a Word Signature? The signature of a word are all of it's letters put in order - the signatures of this, hist and ...
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### Shortest Program to Sort a List of numbers into Odd and Even Category

In the New Modern Times, when Charlie Chaplin encounters a computer, he is employed in the sorting Yard, as a validator to determine if the workers are correctly sorting the items. The Items in ...
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### 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 ...
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### 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 ...
607 views

### Burrows, Wheeler and Back

Background The Burrows–Wheeler transform (BWT) is a reversible permutation of the characters of a string that results in large runs of similar characters for certain types of strings such as plain ...
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### Interleave strings

Inspiration.* I cannot believe we have not had this challenge before: Task Given one or more printable ASCII strings, interleave them by taking one character from each string, cyclically until out ...
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### Rank a list of integers

You're given a non-empty list of positive integers, e.g. [6 2 9 7 2 6 5 3 3 4] You should rank these numbers by their value, but as is usual in leaderboards, if ...
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### 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 ...
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### Advent Challenge 5: Move the presents to the transport docks!

<< Prev Next >> Thanks to the PPCG community, Santa has managed to remanufacture all of his presents and after the assembly line, the presents are now ready to be moved into the transport docks!...
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### Sort all the pixels of an image by the number of occurrences

Input The name of a file in the raster graphics format of your choice. The chosen format must support at least 8 bits per channel and 3 channels. Output A file in the same format, with the same ...
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### Sort an array only using recursion

Your task is to write a function that sorts an array. Your function: Cannot call other functions (excluding itself, of course); Must receive an array of integers as input, and it must return the ...
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### Sort useless characters

This challenge is inspired by this very nice answer by TidB. In TidB's answer, every eight character is in the correct order: gnilwoB edoC (...
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### The Golf (re)Sort [closed]

The Golf (re)Sort Everyone is sorting arrays these days, and so do we at our day jobs. But we like to go out golfing. When we do, we sure like to take our time. It is important to have a stress free ...
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### Sort-a-number. Sorta

Inspired by the ill-fated sorting-a-numbers-digits-without-using-an-array, but I thought it made a better code golf than SO question. Given a positive integer, sort the digits in that integer. ...
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### 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 ...
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### Merge two sorted lists

Merge Sort In this challenge, you will implement the merge subroutine of merge sort. Specifically, you must create a function or program or verb or similar which takes two lists, each sorted in ...
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### DropSort it like it's hot

As described in this question: 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 ...
2k views

### Visualize Merge Sort

Merge sort is a sorting algorithm which works by splitting a given list in half, recursively sorting both smaller lists, and merging them back together to one sorted list. The base case of the ...
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### Crazy Librarian's Amazing Sorting System

It's back to school season! So for a part-time job, you're helping out at the school's library. The problem is, the head librarian has never even heard the words "Dewey Decimal," let alone implemented ...
874 views

### Hungarian alphabetical order

For those who wish a lot more challenge then the old Spanish alphabetical order, let's take a look at how the Hungarian alphabet is ordered. a, á, b, c, cs, d, dz, dzs, e, é, f, g, gy, h, i, í, j, ...
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### Sign that word 2!

Sign that word 2! Not that long ago, I posted a challenge called Sign that word!. In the challenge, you must find the signature of word, which is the letters put in order (e.g. The signature of ...
3k views

My first code golf post, apologies for any mistakes... Context In rock climbing (bouldering specifically), the V/Vermin (USA) climbing grades start at 'VB' (the easiest grade), and then go 'V0', 'V0+...
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### 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 ...
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### Book Stack Sort

When stacking books you usually want to put the largest ones at the bottom and the smallest ones at the top. However, my latent OCD makes me feel very uneasy if I've got two books where one is shorter ...
15k 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 ...
764 views

### Stable positive/negative separation [closed]

From SO. You are given an array with positive and negative integers. Write a function to change the elements order in the array such that negative integers are at the beginning, the positive integers ...
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### Convert binary search tree into ordered linked list

Write the shortest possible program that turns a binary search tree into an ordered doubly-linked list, by modifying the pointers to the left and the right children of each node. Arguments: a pointer ...
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### 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 ...
5k views

### Eating Candy in the Correct Order

When it comes to eating candy, I hold myself to higher standards than the typical layperson. There is a delicate balance between "mixing it up" and "saving the best for last." In this challenge, you ...
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### 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 ...
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### Fairly rank values

Task Given an input list of integers x1…xn, compute a list of ranks r1…rn (a permutation of {1…n}) so that xr1 ≤ xr2 ≤ … ≤ xrn. Then, for each xi, replace its rank by ...
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### Old Spanish alphabetical order

Before 1994, Spanish dictionaries used alphabetical order with a peculiarity: digraphs ll and ch were considered as if they were ...
502 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 ...