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Questions tagged [array-manipulation]

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

10
votes
2answers
275 views

Golf my Ada arrays

Background Ada is a programming language that is not exactly known for its terseness. However, its array literal syntax can in theory allow for fairly terse array specifications. Here is a simple ...
3
votes
4answers
392 views

Intercommunication between threads [closed]

So glad I found this cool site. Wanted to try sharing a coding challenge a friend gave me, an interview question. Usually it is written in java, but you can use whatever language you want, just have ...
16
votes
22answers
902 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 ...
-2
votes
6answers
235 views

Map values to any multidimensional array [closed]

Codegolf challenge - mapping values in a multidimensional array [ [0, 0, 0], [0, 0, 0], [0, 0, 0] ] This 2D array is sick of being so false, and wants to ...
23
votes
20answers
1k views

Maximum summed subsequences with non-adjacent items

Introduction: Inspired by these two SO questions (no doubt from the same class): print the elements in the subarray of maximum sum without adjacent elements java and Maximum sum of non adjacent ...
21
votes
12answers
1k views

Slither Like a Snake

The Idea We've done matrix spirals before, and full rotations, and even diagonal rotations, but not, as far as I can find, snake rotations! What is a snake rotation? Imagine the rows of a matrix ...
19
votes
10answers
477 views

Reorder a Master List Based on a Reordered Subset

I recently had a problem to solve at work where I had two lists: a master list, and a smaller list that contains a subset of the items in the master list potentially in a different order. I needed to ...
10
votes
5answers
464 views

Consistent Overhead Byte Stuffing (COBS)

I'm surprised this hasn't been posted before! The Consistent Overhead Byte Stuffing (COBS) algorithm is used to delimit byte streams. We choose a frame marker (we'll use 0x00) and wherever 0x00 ...
28
votes
19answers
2k views

Rotate a column

Given an integer k and either a block of text, or a 2d array that the inner arrays may have unequal lengths (that resembles a block of text), rotate every character or element in the k-th column up or ...
17
votes
26answers
832 views

Calculating total slots

Given a list of jobs, which must be done in order, with each taking a slot to do, how long will it take to perform them all if after doing a job the same job cannot be done for the next two slots (...
-3
votes
1answer
209 views

Morse sudo-ku-de

Hehe, see what I did with the title? Anyways... Your job is to create a sudoku solver that accepts input in Morse code and creates output in Morse code. Here's the Morse code numbers for reference: <...
40
votes
30answers
3k views

Print a physical multiplication table

Rectangles have this nice property - an \$n \times m\$ rectangle consists of exactly \$n \times m\$ characters! A.. more interesting property is that the rectangles can be aligned nicely in a ...
30
votes
23answers
8k views

Could you please stop shuffling the deck and play already?

Challenge: Input: A list of distinct positive integers within the range \$[1, \text{list-size}]\$. Output: An integer: the amount of times the list is riffle-shuffled. For a list, this means the ...
15
votes
22answers
3k views

Deal the cards to the players

Tonight is card game night! You are the dealer and your task is to write a program to deal the cards to the players. Given an array of cards and the number of players, you need to split the array of ...
20
votes
38answers
3k views

Create chunks from an array

Your task is to write a program which given an array and a number, you need to split the array into chunks with size is number. Rules Your program will receive an array ...
20
votes
46answers
2k views

Count repetitions of an array

You will receive an array and must return the number of integers that occur more than once. [234, 2, 12, 234, 5, 10, 1000, 2, 99, 234] This will return 2, since ...
15
votes
7answers
2k views

Borderless table

In this challenge you are going to place letters from the alphabet in a Cartesian plane and output the result as a text. Your input will consist in a list of list with 3 parameters: X coordinate Y ...
43
votes
23answers
4k views

Covering a Skyline with brush strokes

Given a non-negative integer skyline height list, answer how many uninterrupted 1-unit-high horizontal brush strokes are needed to cover it. [1,3,2,1,2,1,5,3,3,4,2]...
21
votes
23answers
3k views

Pointer jumping

Suppose we have an array \$\texttt{ps}\$ of length \$n\$ with pointers pointing to some location in the array: The process of "pointer jumping" will set every pointer to the location the pointer it ...
3
votes
6answers
276 views

Nested lists as printable 2D objects [closed]

I don't know if something like this exists already (and I'm not finding the right key words) but if not, it felt like it could be an interesting coding puzzle. The challenge is, to take an ...
5
votes
2answers
253 views

Execute Triangularity Move

TL;DR for those not interested: Look at the test cases at the bottom. Have a program/function that outputs the 2D list displayed for the given input. Introduction: On November 15th, 2018 puzzle ...
12
votes
13answers
477 views

Count the contiguous submatrices

Migrated from chat Given two non-empty non-negative integer matrices A and B, answer the number of times A occurs as a contiguous, possibly overlapping, submatrix in B. Examples/Rules 0. There may ...
22
votes
13answers
2k views

Coat of Many Colours

Challenge Given a list of unique colour names as input, sort them in the order that they first appear in Joseph's Amazing Technicolour Dreamcoat. Example ...
25
votes
16answers
2k views

Non-overlapping Matrix Sum

Non-overlapping Matrix Sum Given k arrays of length n, output the maximum sum possible using one element from each array such that no two elements are from the same index. It is guaranteed that k<=...
15
votes
8answers
2k views

Rotation invariant fingerprinting

Imagine we have some polyomino and would like to uniquely identify them, however the polyominos can be rotated, so blindly hashing them won't give us the same fingerprint for a piece and a rotation ...
14
votes
25answers
1k views

Standardize the Samples (Compute the z-Score)

Given a list of floating point numbers, standardize it. Details A list \$x_1,x_2,\ldots,x_n\$ is standardized if the mean of all values is 0, and the standard deviation is 1. One way to compute this ...
7
votes
1answer
378 views

Hilbertize an image

For a computer vision app I want to do a mapping of an image, in such a way that every pixel fit hilbert curve, instead of conventional layout. So task could be as follows: Task description Given ...
34
votes
64answers
5k views

P Pr Pre Pref Prefi Prefix Prefixe Prefixes

Given some finite list, return a list of all its prefixes, including an empty list, in ascending order of their length. (Basically implementing the Haskell function ...
10
votes
11answers
519 views

Map the cheaters!

After all assignments are submitted, a dictionary is created that maps student number to the hash of their file. This dictionary, or hashmap, or mapping (whatever your language calls it) will look as ...
21
votes
17answers
2k views

Split Mark's marks

Challenge Mark is a student who receives his N marks in a concatenated way in a one single line. The challenge is to separate his marks, knowing that each mark ...
8
votes
2answers
171 views

Let's play Peg Solitaire

Peg solitaire is a popular game usually played alone. The game consists of some number of pegs and a board which is divided into a grid - usually the board is not rectangular but for this challenge we ...
7
votes
4answers
387 views

Sort a list, poorly

Don't you hate it when you're trying to roughly sort a list based on user data, but you have to poll the user for thousands of comparisons? Hate no more, because the answers to this challenge are (...
1
vote
9answers
201 views

Finding the period of a recurring element in an array [closed]

Given an array A of integers, there exists at least one positive integer p such that A[i] == A[j] for all ...
9
votes
1answer
260 views

Dyadic Transpose

As with most APL symbols, has different meanings when called with one argument (transpose) versus two arguments (dyadic transpose / reorder dimensions). This ...
24
votes
15answers
2k views

All the single eights

Given a non-empty rectangular array of integers from 0 to 9, output the amount of cells that are ...
12
votes
6answers
644 views

Determine the Widest Valley

Imagine we get a slice of some mountainous region, this would result in a shape similar to this: ...
19
votes
3answers
361 views

Count cyclically self-describing lists

Cyclically self-describing lists A list \$L\$ of positive integers is cyclically self-describing, if the following conditions hold. \$L\$ is nonempty. The first and last elements of \$L\$ are ...
19
votes
10answers
2k views

Repeat this GCD operation

Problem A3 from the 2008 Putnam competition says: Start with a finite sequence \$a_1, a_2, \dots, a_n\$ of positive integers. If possible, choose two indices \$j < k\$ such that \$a_j\$ does not ...
21
votes
15answers
4k views

My array should equal this, but it doesn't!

Given an array of integers a which contains n integers, and a single integer x; remove the fewest amount of elements from ...
13
votes
16answers
2k views

Trim that distracting background off!

Isn't it annoying when you're taking a picture, but the background detracts from the actual substance of the image? I'd say it is. I need to know how much I should crop so that I get rid of this ...
4
votes
10answers
472 views

Smoothing a pair of arrays

Input Two lists with binary values (list_a, list_b) of equal length=>3. Output Two lists with binary values ...
-4
votes
20answers
399 views

Array indexes to number and number reversed

Given an input array having minimum length 2 and maximum length 9 having any initial values output an array having length ...
18
votes
7answers
814 views

Find an array that fits a set of sums

Consider an array A of length n. The array contains only positive integers. For example ...
9
votes
24answers
946 views

Multiplicative undelta

Let us define the "multiplicative deltas" of values \$[\; a_0, \cdots a_N, \;]\$ as: $$ [\; a_1 / a_0, \cdots, a_{i+1} / a_i, \cdots, a_N / a_{N-1} \;] $$ The reverse operation - namely "...
15
votes
9answers
611 views

Stagger, stack, sum

Inspired by this Stack Overflow question. The challenge Input An array of square matrices containing non-negative integers. Output A square matrix built from the input matrices as follows. Let \$...
26
votes
23answers
2k views

Equalize the array

Challenge You are given an array \$a\$ of integers. With a move you can increase or decrease an element of the array by 1. Your task is to equalize the array, that is make all the elements of the ...
16
votes
2answers
501 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 ...
10
votes
7answers
641 views

Whose neighbours are hostile?

Introduction For the purposes of this challenge, we will define the neighbours of an element \$E\$ in a square matrix \$A\$ (such that \$E=A_{i,j}\$) as all the entries of \$A\$ that are immediately ...
14
votes
20answers
1k views

Block-sorting rows and columns in a 2D array

Given a 2D array of integers, let's sort its rows and columns in blocks. This means that you only have to sort a given row or column, but applying the transformations needed for sorting it to every ...
21
votes
14answers
2k views

Chop off the matrix to get the desired sum

Definition Given a matrix \$M\$ of non-negative integers and a non-negative integer \$k\$, we define \$F_k\$ as the "chop-off" function that removes all rows and all columns in \$M\$ that contain \$k\...