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Questions tagged [array-manipulation]

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

15
votes
21answers
1k views

Fill up to duplicate ranges

Let \$L\$ be a list of positive integers with no particular ordering, and which can contain duplicates. Write a program or function which outputs a list of positive integers \$M\$ (whose ordering is ...
19
votes
11answers
2k views

A knight's graph on an N-by-N board

In chess, a knight can only move to the positions marked with X relative to its current position, marked with ♞: A Knight's Graph is a graph that represents all legal moves of the knight chess piece ...
-7
votes
0answers
92 views

Php arrays code challenge [closed]

Given an array, write a function that will traverse the array and generate the array in a format given in the example below. For example, given the array: ...
8
votes
15answers
665 views

Scoring 6,5,4 (AKA Ship, Captain, and Crew)

Inspired and looted from this dice challenge by Arnauld Input You are given a 5x1 or 1x5 (your choice) dice matrix which consist of binary 3x3 sub-matrices. Goal Given a valid dice matrix, you are ...
22
votes
22answers
3k views

Most Common Multiple

Not to be confused with Least Common Multiple. Given a list of positive integers with more than one element, return the most common product of two elements in the array. For example, the MCM of the ...
11
votes
5answers
306 views

Minimal Centrosymmetrization

Topically related. Objective: Given a matrix of positive integers \$M\$, output the smallest centrosymmetric matrix which contains \$M\$ (this matrix may contain non-positive integers as well). A ...
6
votes
1answer
77 views

Make the super number hyper-pyramid [duplicate]

Challenge Given a positive integer \$n\$, output the \$n\$-dimensional pyramidal list. Example \$n = 1\$: Objects arranged in a 1D pyramid (line) with side length 1 is just by itself. So, the ...
9
votes
2answers
148 views

Optimal Caching

You will be given a sequence of memory requests and a cache size. You must return the least possible number of cache misses under any cache replacement strategy. An optimal strategy is Belady's ...
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 ...
37
votes
28answers
3k views

Remove surrounding zeroes of a 2d array

This is a 2-dimensional version of this question. Given a non-empty 2-dimensional array/matrix containing only non-negative integers: $$ \begin{bmatrix} {\color{Red}0} & {\color{Red}0} & {\...
41
votes
73answers
7k views

Implementing a stack

I can't believe we don't have this already.. It's one of the most important data-structures in programming, yet still simple enough to implement it in a code-golf: Challenge Your task is to ...
5
votes
4answers
345 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 ...
13
votes
3answers
403 views

Multi-level free parking space finder

Kids-related intro Whenever I take my kids to an amusement park, the kids get more nervous the closer we are to the park, with the nerve peak when we are in the parking lot and find no place to park. ...
37
votes
28answers
4k views

Is the matrix centrosymmetric… and so is the code?

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] \...
9
votes
10answers
582 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 ...
11
votes
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, ...
12
votes
11answers
711 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 ...
12
votes
3answers
269 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 ...
13
votes
1answer
286 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 ...
17
votes
3answers
435 views

Dead Frog Walking

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 ...
21
votes
28answers
2k views

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 ...
1
vote
0answers
72 views

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 ...
34
votes
20answers
3k views

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 ...
1
vote
5answers
297 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. ...
8
votes
25answers
647 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 ...
16
votes
20answers
1k views

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 ...
14
votes
23answers
776 views

Equal numbers in sub-array

Given an array of numbers with length >=3 and length % 3 == 0 [1, 2, 3, 4, ...] You ...
16
votes
8answers
539 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 ...
10
votes
22answers
1k views

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 ...
0
votes
0answers
107 views

Validate Sudoku (N by N) [duplicate]

Challenge : Create a random (pseudo random) Sudoku board with dimension n x n Input : Given : ...
11
votes
12answers
818 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): ...
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 ...
12
votes
13answers
673 views

Grouping Array Data

Given an integer matrix a and a nonnegative integer i, output a mapping b that maps the ...
24
votes
12answers
2k views

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 ...
24
votes
15answers
1k views

Modular broadcasting

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 ...
10
votes
26answers
2k views

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: ...
11
votes
2answers
278 views

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 ...
8
votes
1answer
389 views

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 ...
43
votes
41answers
5k views

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 ...
15
votes
3answers
963 views

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 ...
10
votes
4answers
657 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. ...
14
votes
6answers
930 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 ...
13
votes
12answers
714 views

Circle intersection area

Description : Given x and y positions of two circles along with their radii, output the ...
11
votes
2answers
357 views

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 ...
17
votes
23answers
2k views

Sort spelled-out serial numbers

Given a list of two or more spelled-out serial numbers of equal length greater than two, e.g. ...
14
votes
9answers
1k views

Block Rearrangement

So your task is to take a 3x3 block where -'s mean blank spaces, and *'s mean filled spaces, for example: ...
-7
votes
7answers
135 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 ...
21
votes
20answers
893 views

Reverse Range Successors

Given a positive integer n, do the following (and output every stage): start with a list containing n copies of ...
16
votes
13answers
874 views

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 ...
26
votes
36answers
4k views

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 ...