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

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12
votes
8answers
538 views

Collect and place items

The goal of this challenge is to collect selected items in a list and move them to a certain location in the list. As a visual example, take the input values (represented by black boxed integers) and ...
8
votes
4answers
183 views

Sort a list of unknown values with the least amount of comparisons

In this optimization challenge you will write a program that sorts a single array by only comparing elements through asking the user on stdout to input comparison results on stdin. The below protocol ...
22
votes
23answers
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 [1,3,0,2,4]. Note that the two 8s maintain ...
22
votes
21answers
1k views

Post-determined Array Sorting

Input: An array containing three integers: 0, 1 and 2 in any order (i.e. [2, 0, 1]) And a string of length >= 2 only containing alphabetic letters (both lower- and uppercase) and digits (i.e. a1B2c3)...
23
votes
28answers
1k 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 each digit in n. Examples: Input: 101 >> one, zero, one >> ...
13
votes
16answers
654 views

Reverse odd runs

Inspiration. Task Reverse runs of odd numbers in a given list of 2 to 215 non-negative integers. Examples 0 1 → 0 1 1 3 → 3 1 1 2 3 → 1 2 3 1 3 2 → 3 1 2 10 ...
23
votes
11answers
1k views

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 ...
6
votes
1answer
336 views

QWERTY Quine Creation

Challenge Create a quine, that instead of outputting it's source, output's it's source QWERTY-sorted. What is QWERTY sorting? QWERTY sorting is sorting code by the QWERTY keyboard. Anything higher ...
24
votes
31answers
3k views

Driftsort an array

Driftsort is a simple way to "sort" an array. It works by "sliding" or "rotating" the elements over in the array until the array is sorted, or until the array fails to be sorted. Let's walk through ...
8
votes
28answers
2k 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. list....
14
votes
6answers
297 views

Insert semi-sorted into unsorted array

Welcome to your first day at PPCG Inc. As our newest junior assistant document sorter, you are responsible for making sure all documents we sent down to you are archived in alphabetical order. It's so ...
13
votes
16answers
789 views

Sorting rectangular matrices

Given a matrix A, we can say that it is "sorted" if each row and column of A is sorted (ascending left-to-right for rows and top-to-bottom for columns). Thus, this matrix is sorted: [ 1 2 3 4 5 ] [ 2 ...
11
votes
9answers
1k views

A classic sorting code-golf question

This is a code-golf question. Input A list of non-negative integers in whatever format is the most convenient. Output The same list in sorted order in whatever format is the most convenient. ...
22
votes
9answers
1k views

Sort a nested list

You must write a program or function that sorts a nested list. Here are the rules for sorting a nested list: Let's take this list as an example: ((5, 2), 2, 7, (2, 1, (3, 4)), 9) Each element in ...
11
votes
7answers
343 views

Sort items based on dependency

Goal Sort a list of items ensuring that each item is listed after its specified dependencies. Input An array of arrays of integers, where each integer specifies the 0-based or 1-based index of ...
14
votes
3answers
373 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, ...
20
votes
6answers
1k views

Old Spanish alphabetical order

Before 1994, Spanish dictionaries used alphabetical order with a peculiarity: digraphs ll and ch were considered as if they were single letters. ch immediately followed c , and ll immediately followed ...
30
votes
8answers
3k views

Sort these James Bond ratings

Introduction My grandpa is a fan of James Bond, but he is always unsure on how to rank his favourite actors. As such, he is always making lists, which is a lot of work. He asked me to produce a ...
22
votes
3answers
503 views

Sort these bond ratings

The task The credit rating agencies assign ratings to bonds according to the credit-worthiness of the issuer, and the "Big Three" credit rating agencies use a similar (though not identical) tiered ...
0
votes
3answers
243 views

Write a radix sort

Goal As the title suggests, write a radix sort function (either MSB or LSB is fine) that accepts two parameters: an array of values of any type (you can assume that they are all of the same type / ...
29
votes
17answers
2k views

Show the Top Five Comment Scores on a SE Post

A Stack Exchange script determines which five comments on questions or answers are initially seen on the main page of sites through the number of upvotes on them; the five comments with the highest ...
9
votes
1answer
217 views

Sort scrambled two-dimensional array filled with numbers by swapping adjacent numbers [closed]

A two-dimensional array of size n×n is filled with n*n numbers, starting from number 1. Those numbers are to be sorted per row in ascending order; the first number of a row must be greater than the ...
7
votes
0answers
183 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. ...
34
votes
33answers
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 looks something like this: 0....
86
votes
15answers
3k views

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 N, such that the list consisting of bi = ai XOR N is sorted. If ...
10
votes
4answers
201 views

Title Keywords in Context

This challenge is based on a problem described in D. Parnas, On the criteria to be used in decomposing systems into modules, and elaborated upon in J. Morris, Real Programming in Functional Languages. ...
12
votes
8answers
478 views

Typesetting multidimensional labels

In a steam-punk multidimensional world, our boss wants to affix printed index labels to each drawer in our conglomerate's multidimensional file cabinet. The boss wants to typeset the entire label ...
24
votes
19answers
2k views

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 ...
23
votes
21answers
2k views

Sort this, quick!

Well... there are 59 (now 60) questions tagged sorting, but no simple quicksorts. That must be fixed. For those unfamiliar with quicksort, here is a breakdown, courtesy of Wikipedia- Pick an ...
-1
votes
2answers
110 views

Epcot World Reorder

Intoroduction If you've ever been to Epcot at Disney World, you've probably been to the world showcase: a lake surrounded by various country-themed locations. One thing that's always bothered me ...
36
votes
37answers
4k 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 ...
1
vote
0answers
88 views

Anagram Bubble Sorter [closed]

The Challenge A bubble sort takes a list of non-repeating integers and sorts them in ascending order, with only the use of one operation: switching two numbers which are next to eachother. However ...
0
votes
1answer
252 views

The Truck Problem [closed]

I am a teacher who was given a problem a few years ago. Every year since I have given it to my advanced students as a bonus assignment, but in ~10 years only 8 solved it, each with a slightly ...
18
votes
7answers
939 views

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 ...
4
votes
2answers
460 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 ...
68
votes
15answers
3k 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. Your challenge is to remedy this ...
17
votes
23answers
2k views

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 this ...
14
votes
43answers
4k views

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 hits are all hist. The Challenge Write a program program should ask for an ...
31
votes
6answers
1k views

Sort the Textbooks

Sort the Textbooks School is starting soon (if it hasn't already) and so it's time to get our textbooks in order. You need to sort your books in alphabetical order but that takes too long so you ...
13
votes
3answers
493 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 ...
8
votes
2answers
331 views

Sorting for Bozos

Introduction This challenge is about three (bad) sorting algorithms: Bogosort, and two others variants that I came up with (but have probably been thought of by others at some point in time): ...
15
votes
14answers
2k views

CodeGolf - Ignore the noise #1

Instructions Barry is a not so good backend developer in charge of a small API that should give you information about purchases made in a client's shop. However, he hasn't done a great job and your ...
8
votes
12answers
975 views

Rearranging a set of numbers into order

The Question Given a set of 9 numbers, m[], which contains only numbers 1 through 9 in a random order, with no two numbers being the same, create a program in any language which rearranges the number ...
12
votes
3answers
292 views

Books on a Shelf

I have some books and a bookshelf. I would like to put as many books on the shelf as possible but I have a rule. All dimensions of the books (height, width and depth) should form a non-increasing ...
8
votes
5answers
359 views

Decide existence of total orderings

In this task, we consider arrays of positive integers such as this: 3 18 321 17 4 4 51 1 293 17 The input comprises a pair of such arrays both of arbitrary, possibly distinct, positive length. ...
-1
votes
3answers
108 views

Detect the main order based on sub-lists [closed]

The question is simple but the answer maybe not! suppose that you have the following lists that all of them are ordered (not consecutive): x = ['one', 'two', 'four'] y = ['two', 'three', 'five'] z =...
8
votes
6answers
1k views

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 ...
12
votes
3answers
687 views

Un-Merge a List

Introduction Most of you are familiar with the merge sort algorithm for sorting a list of numbers. As part of the algorithm, one writes a helper function called merge that combines two sorted lists ...
7
votes
5answers
211 views

Almost Lexicographical List Comparison

Input Two lists A and B of nonnegative integers. Output Either 1, 0, or -1, depending on whether A is larger than, equal to, or smaller than B with respect to the twisted lexicographical ordering ...
8
votes
9answers
474 views

Ordering an array of negatives, zero and positives integers with one iteration

Take an array of integers containing negative numbers, positive numbers and zeros. Group it with one iteration and in place such that all of the negative numbers come first, followed by all of the ...