# Questions tagged [array-manipulation]

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

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Defintion A centrosymmetric matrix is a square matrix that is symmetric about its center. More rigorously, a matrix $A$ of size $n \times n$ is centrosymmetric if, for any $i,\: j \in ([1, n] \... 10answers 603 views ### Tuples by sequentially stepping through entries in list of lists Challenge: Given a list of nonempty lists of integers, return a list of tuples of the following form: First list tuples starting with each element of the first list followed by the first element of ... 13answers 1k views ### First Last Last First Challenge The task is simple. Given an array and a first and last value: Return the first of the last after the first, and the last of the first before the last. Or simply: Given an array, var1, ... 11answers 722 views ### Find the minimum cost matching between arrays of integers Consider two sorted arrays of integers$X$and$Y$of size$m$and$n$respectively with$m < n$. For example$ X = (1,4)$,$Y = (2,10,11)$. We say that a matching is some way of ... 3answers 301 views ### Optimize my Nullifiers I am a big fan of the game Creeper World, and especially the sequel. You don't need to know how this game works to answer the question, I just wanted to mention where my question originated from. In ... 1answer 316 views ### FIFO cache anomalies This is the followup challenge from this one, if you're confused please check that one out first. First, let$m(s, k)$be the number of cache misses a sequence$s\\$ of resource accesses would have ...
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Introduction Jonny wants to play Frogger. However, he's not very good. In fact, he will only try to move forward, and only after the platforms have moved. Find out if Jonny's frog manages to reach ...
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### Replace me by the sum of my cyclic successors!

I have a simple challenge for you this time. Given an array of positive integers A (or the equivalent in your language), replace each entry Ai with the sum of the next Ai elements of A, cycling back ...
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### Finding Fastest Frog's Frolicks [duplicate]

A frog sits on a lily pad wishing it were on the other side of the river. There are some lily pads of varying sizes between the frog and the other side of the river. Larger lily pads allow the frog ...
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### Number of FIFO cache misses

This challenge is really simple (and a precursor to a more difficult one!). Given an array of resource accesses (simply denoted by nonnegative integers) and a parameter ...
369 views

### String Array to JSON String

Introduction I've seen throughout the code-golf challenges several simple tasks involving JSON, such as interpreting JSON strings with RegExs, and almost every other manipulation I could think of. ...
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### 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 ...
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### Get the sequence steps

Challenge Given a sequence of numbers, create a function which returns the sequence steps. Assume a sequence will be N >= 3 Sequence will repeat it steps at ...
958 views

### Equal numbers in sub-array

Given an array of numbers with length >=3 and length % 3 == 0 [1, 2, 3, 4, ...] You ...
676 views

### Classify a region by its slope

Definitions The kth ring of a square matrix of size N, where 1 ≤ k ≤ ceiling(N/2) is the list formed by the elements of the kth and (N-k+1)th rows and columns, but without the first and last k-1 ...
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### Cartesian product of a list with itself n times

When given a a list of values and a positive integer n, your code should output the cartesian product of the list with itself n ...
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### Validate Sudoku (N by N) [duplicate]

Challenge : Create a random (pseudo random) Sudoku board with dimension n x n Input : Given : ...
834 views

### Sum of replicated matrices

Given a list of numbers [ a1 a2 ... an ], compute the sum of all the matrices Aᵢ where Aᵢ is defined as follows (m is the maximum of all aᵢ): ...
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### 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 ...
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### Grouping Array Data

Given an integer matrix a and a nonnegative integer i, output a mapping b that maps the ...
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### Find arsonist's lullaby

Imagine an arsonist walking around the town and picking its victims according to a very specific pattern (Or, alternatively, Imagine a bee flying around the garden and picking its flowers to pollenize ...
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This challenge is related to some of the MATL language's features, as part of the May 2018 Language of the Month event. Introduction In MATL, many two-input functions work element-wise with ...
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### Weighted average - the pressup trend problem

Let's say that this array is how many press-ups I've achieved each day in the last 28 days: ...
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### Find out my number neighbors

The input consists of i rows with neighbors information. Each ith row contains 4 values, representing the neighbor of i to the North, East, South and West directions, respectively. So each value ...
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### Implement Tyrant Sort [closed]

TL;DR Record (left-right)/length for each pair of consecutive elements. If they're 0 or negative, don't record it. Once this is done, take these actions. Don't update quotients: Increment right and ...
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### Detect heat waves

Background The Royal Netherlands Meteorological Institute defines a heat wave* as a series of at least 5 consecutive days of ≥25°C weather (“summery weather”), such that at least 3 of ...
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### How to swap elements in a vector using an anonymous function in Octave?

Swapping two elements in a vector/matrix is very simple in Octave: x='abcde'; x([4,1])=x([1,4]) x = dbcae Unfortunately, I have yet to find a way to do this ...
720 views

### The Top Ten Elements You Won't BELIEVE Are In This Array

AKA: Generate Clickbait From an Array. Given an array of integers, generate some cringe-worthy clickbait based on its arrangement and length: If it's 20 elements or less, you can make a Top X List. ...
963 views

### Will you be my Weaver?

I've been recently playing through 'The Weaver' and I think it presents an interesting challenge for code-golf. Premise: The Weaver is a game wherein you are given a number of ribbons coming from 2 ...
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### Circle intersection area

Description : Given x and y positions of two circles along with their radii, output the ...
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### The Lonely Islands

Input: A 2D array containing two distinct (optional) values. I'll use 0 and 1 when explaining the rules. The input format is of course flexible. Challenge: Zeros are water, and ones are islands. In ...
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### Sort spelled-out serial numbers

Given a list of two or more spelled-out serial numbers of equal length greater than two, e.g. ...
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### Block Rearrangement

So your task is to take a 3x3 block where -'s mean blank spaces, and *'s mean filled spaces, for example: ...
156 views

### Make Arrays/Lists start at one [closed]

Introduction For as long as programmers have been programming and as long as English teachers have been teaching, there's a controversy over the datasets called Arrays and Lists (or hashes). Arrays ...
948 views

### Reverse Range Successors

Given a positive integer n, do the following (and output every stage): start with a list containing n copies of ...
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### Running gene crossover algorithm

Your task is to accept as input two gene sequences, and a sequence of "cross over points", and return the gene sequence that results from the indicated cross overs. What I mean by this is, say you ...
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### Implement Lazy Drop Sort

This challenge already describes dropsort. However, I'm kinda lazy and I really only need my array to be a bit more sorted than before, it doesn't need to be sorted all the way. In Drop Sort, we drop ...
1k views

Self-limiting lists Consider a nonempty list L containing nonnegative integers. A run in L is a contiguous sublist of equal elements, which cannot be made longer. For example, the runs of [0,0,1,1,3,...
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### Fastest to find the joint

The input is an array (or space-separated string, as you wish), zero-indexed, consisting of one strictly increasing array and one strictly decreasing array (in this order, not other vice versa), each ...
425 views

### Help John watch movies!

Introduction So John finally has his holidays! And what better could he do than watching some movies. He indeed has a lot of movies to watch, but he is unable to decide which one to watch first. He ...
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### Rebuild a rectangular array from a corner

I once had a beautiful rectangular array. It was very symmetrical, but unfortunately it has fallen apart and now I only have the top left corner. Your task will be to rebuild the original array. Your ...
642 views

### Sort by shuffling blocks

Block shuffle sort The block shuffle sort is a (rather artificial) method of sorting a list. It works as follows, illustrated by an example. ...
388 views

### Visit and exit an array

Challenge: Input: An integer n (> 0) An integer-array a of size ...
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### How to print the below format in the fewest bytes?

This challenge is inspired by this, now deleted question. Take a positive integer N as input, and output a matrix with the numbers 1 .. N2 that follows the pattern below: Fill in the first row with ...
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### Quickly regrouping lists

Grouping takes a list and splits it into new lists of equal adjacent elements. For example [1,1,2,1,1] -> [[1,1],[2],[1,1]] If you then take the length of ...
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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 ...
550 views

### 1D Hopping Array Maze

Inspired by We do tower hopping and related to 2D Maze Minus 1D Introduction Your task is to find the shortest path to get out of an array maze following specified rules. Challenge A 1D array a ...
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### We do tower hopping

Task Given an array of non-negative integers a, determine the minimum number of rightward jumps required to jump "outside" the array, starting at position 0, or ...
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### The weight of a Zero

Given an ordered list of numbers (possibly with leading zeros), arrange the numbers vertically, then let all zeros drop all the way to the bottom and all overhangs drop to the bottom-most open slot. ...
738 views