Questions tagged [array-manipulation]

A competition to solve a particular problem through the usage and manipulation of arrays.

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26
votes
33answers
5k views

Separate a list into even-indexed and odd-indexed parts

Inspired by this question: Make a function (or a full program) that receives a list of numbers and outputs the list rearranged, so that even-indexed numbers appear first, and odd-indexed numbers ...
23
votes
25answers
3k views

Numbers Increase While Letters Decrease

Inspired by this Stack Overflow question: Sorting a list: numbers in ascending, letters in descending. Your task is to solve the following problem and, as this is code-golf, you should do so in as few ...
22
votes
27answers
966 views

Sort a difference list

The difference list of a list of integers is the list differences of consecutive members. For example the difference list of 1, 3, 2 ,4 is ...
21
votes
9answers
2k views

How much is my dice matrix worth?

Input A non-empty binary matrix consisting of 3x3 sub-matrices put side by side. Task Your task is to identify valid dice patterns (as described below) among the 3x3 sub-matrices. Each valid ...
20
votes
15answers
2k views

Function clipboard: paste

This challenge is related to some of the MATL language's features, as part of the May 2018 Language of the Month event. Associated challenge: Function clipboard: copy. Introduction MATL's function ...
19
votes
11answers
943 views

Calculate the bounded cumulative sum of a vector

The cumulative sum of a vector is calculated by simply taking the sum of all previous elements. For instance: ...
18
votes
18answers
1k views

Reverse Maths Cycles

Inspired by this In the linked challenge, we are asked to apply addition to the elements of the original and the reverse of the input array. In this challenge, we are going to make it slightly more ...
18
votes
10answers
1k views

Minimally sort a list into a matrix

Given an unsorted list of unique strictly positive integers, minimally sort it into a 2D matrix. The input list is guaranteed to be of composite length, which means the output matrix is not ...
17
votes
23answers
1k views

Enumerate Derangements

Given some positive integer \$n\$ generate all derangements of \$n\$ objects. Details A derangement is a permutation with no fixed point. (This means in every derangement number \$i\$ cannot be in ...
14
votes
14answers
2k views

Generate all square sub-matrices of a given size

You will be given a square matrix of integers M and another positive integer n, strictly smaller than the size of M. Your task is to generate all square sub-matrices of M of size n. For the purposes ...
13
votes
11answers
984 views

Turn this array into a matrix

Take a non-nested array as input. Turn it into a matrix by using the following method: Let's say my array is [1, 2, 3, 4, 5] First, I repeat that array 5 times: (...
12
votes
6answers
542 views

Topple the sandpile

(There are related questions about infinite sandpiles, and finding identity elements of sandpiles.) Given a matrix of non-negative integers, return a matrix of the same dimensions, but toppled: If ...
11
votes
6answers
917 views

Group Integers by Originality

Introduction: I collect twisty puzzles. Most twisty puzzles are produced and sold by Chinese companies. Most well-known companies ask permission from puzzle designers to produce their designs and ...
10
votes
1answer
158 views

Advent Challenge 8: Storage Cart Transport Planning!

<< Prev Thanks to the PPCG community, Santa now has balanced his storage carts. Now, he needs to move them into the transport docks so that they can be sent to the loading bays. Unfortunately, ...
9
votes
29answers
3k views

The Nine Pattern

Introduction I stumbled across this (useless) pattern the other day while I was watching TV. I named it "the 9 pattern" because the first number to use it was 9. The gist of it is, you enter a number ...
9
votes
4answers
1k views

Calculate a probability exactly

This task is about writing code to compute a probability exactly. The output should be a precise probability written as a fraction in its most reduced form. That is it should never output ...
9
votes
5answers
286 views

Almost Lexicographical List Comparison

Input Two lists A and B of nonnegative integers. Output Either 1, ...
8
votes
25answers
709 views

Find unique elements based on a given key

Input Take a list of values xi each paired with a key yi. [(x1, y1), (x2, y2), ...] Output Return a list L containing only values from the set {xi}. The ...
8
votes
12answers
1k 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 ...
7
votes
4answers
350 views

Count, Replace, Add Up! [duplicate]

Definition Define the nth term of the CRAU sequence as follows. Begin with the singleton array A = [n]. Do the following n times: For each integer k in A, replace the entry k with k natural numbers,...
7
votes
25answers
920 views

Same length sub arrays

Background: Here's a little simple challenge. You want to be able to find out whether the arrays inside an array have the same length. Input: Your input should consist of exactly one array (this is ...
6
votes
3answers
602 views

Compute the Join and Meet of Partitions

Background In this challenge, a partition of a set S means a collection of nonempty subsets of S, which are mutually disjoint ...
1
vote
1answer
208 views

Dyalog's International Problem Solving Competition (Phase I) – Code Golf Edition [closed]

Every year, Dyalog Ltd. holds a student competition. The challenge there is to write good APL code. However, this is a multiple-holes (common theme is manipulation of data of any type and structure, ...

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