Questions tagged [array]
A competition to solve a particular problem through the usage and manipulation of arrays.
653
questions
23
votes
31answers
1k views
+100
Even sum subarrays
Given an array of integers, count the number of contiguous subarrays with an even sum. You may assume that the array is non-empty, and contains only non-negative integers.
This is code-golf, so the ...
14
votes
9answers
1k views
Convert Regex to Mask
From my CMC.
Given a regex and a non-empty printable ASCII text, return one bit per character in the text, indicating the positions of beginnings of non-overlapping matches, and also the positions of ...
2
votes
2answers
87 views
Tips for parsing Standard Input in JavaScript
I've been doing quite a few code golf recently and I realised that a lot of times, I have to do something involving list.
Most of the times lists are space-separated or comma-separated values in the ...
14
votes
22answers
2k views
Ways to add 1 to lists of lists
Adapted from this StackOverflow question
In this challenge you will take a list of lists of integers, e.g.
A = [[1,2],[3,4],[5],[]]
And an additional single ...
26
votes
18answers
2k views
Floating Point indexOf
Given a sorted array of unique positive integers \$A\$ \$(A_0<A_1<\cdots<A_{n-1})\$, and an integer \$t\$, where \$A_0\le t\le A_{n-1}\$. Output the value \$i\$ such that:
If \$t \in A\$, \$...
21
votes
59answers
4k views
Swap every two elements in a list
Challenge
Let's have a list L of n elements. The task is to swap every two elements in this list.
Constrains
the list ...
19
votes
13answers
1k views
Compute matrix blockiness
Consider a non-empty binary matrix M and a natural number n. For the purposes of this challenge, M is said to have blockiness n if it can be built using adjacent square blocks of size n, where each ...
14
votes
20answers
1k views
Rotate N Values in a List
Similar to this.
Input a list and rotate N numbers in it given their indices. The following example uses 1-indexing, but feel free to use either.
In other words, take a list of indices and a list of ...
16
votes
10answers
755 views
Remove submatrices
Given two integer matrices a and b, your challenge is to replace any occurences of b in <...
20
votes
9answers
2k views
Bird's Algorithm for Computing Determinants
There is a division-free algorithm for computing determinants published by R.S.Bird in 2011 that uses only matrix multiplications. Given a \$n×n\$ matrix \$X\$, the matrix \$Y=μ(X)\$ is another \$n×n\$...
22
votes
17answers
2k views
Double trace of a square matrix
Inspired by a question (now closed) at Stack Overflow.
Given a square matrix, let its double trace be defined as the sum of the entries from its main diagonal and its anti-diagonal. These are marked ...
25
votes
42answers
2k views
Swap Two Values in a List
Introduction:
Although we have a lot of challenges where swapping two items in a list is a subtask, like Single swaps of an array; Swap to Sort an Array; \$n\$ swaps into a nop; etc., we don't have ...
8
votes
2answers
578 views
Follow the border
Inspired by Is this Flow Free puzzle trivial? by @Bubbler. Lengthy chunks of this challenge are borrowed from there. This may be one step of a solution for the linked challenge, depending on chosen ...
14
votes
10answers
904 views
Revert Flow Free puzzle
Inspired by Is this Flow Free puzzle trivial? by @Bubbler. Lengthy chunks of this challenge are borrowed from there. This may be one step of a solution for the linked challenge, depending on chosen ...
41
votes
17answers
5k views
Recursive Stalin Sort
There is a "sorting" algorithm often called Stalin Sort, where instead of sorting an array, you just remove any items that are out of order. In this challenge, you'll implement part of a ...
14
votes
2answers
543 views
Is this Flow Free puzzle trivial?
Background
Flow Free is a series of puzzle games whose objective is to connect all the same-colored pairs of dots on the grid. In this challenge, we consider the original game on a rectangular grid (...
5
votes
6answers
182 views
"Fold" the array [duplicate]
An example will easily explain this to you. Suppose an array [1,2,3,4,5]
Step 1
1 2 3 4 5
----+----
Step 2
...
11
votes
15answers
2k views
Minimizing flights of stairs climbed
Challenge
Given input as a list/array of natural numbers that each represent the floor of a class a student has to go to, sort the numbers in a way such that the MAD (mean average deviation) number of ...
13
votes
11answers
3k views
Simulate my pill box
I have a small pill box of \$n\$ slots. (Think of it as a linear one like the image below, but not necessarily having 7 slots.)
Each slot has at most one pill. Every day, I take one of two actions: ...
9
votes
9answers
444 views
\$n\$ swaps into a nop
Given \$n, m\ge 1\$. There are \$n\$ balls. Do \$m\$ moves, each choose a ball (maybe also the first one), and exchange with the one currently on the first place. At the end, the order of balls should ...
21
votes
24answers
3k views
Apply gravity to this matrix
This was inspired by this question.
Given an \$m\times n\$ matrix of \$0\$'s and \$1\$'s, apply "gravity" to it. This means to drop down all the \$1\$'s as if they were affected by gravity.
...
10
votes
7answers
2k views
Game of Life, but on a 4-8-8 tiling
Background
The 4-8-8 tiling looks like this:
For the purpose of this challenge, we take the orientation of the tiling as exactly shown above. In plain English words, we take the tiling so that it can ...
7
votes
4answers
257 views
So is that maximum?
Given a map from arrays of integers of same size to single integers, determine if there is a set of indices such that the output is equal to the maximum of the elements at those indices for every ...
4
votes
0answers
120 views
How many fill buckets to blank? [duplicate]
The fill bucket is a tool available in many drawing tools which replaces a contiguous chunk of one color with a another color.
We are going to define a fill bucket which operates on lists of non-...
12
votes
2answers
253 views
Draw constraint system #18762389
Background
Page 219 of A New Kind of Science (a book by Stephen Wolfram, the creator of Mathematica) shows an interesting 2D pattern generated by constraints. The relevant section in the book starts ...
24
votes
31answers
3k views
"-rot" transform
Background
-rot transform (read as "minus-rot transform") is a sequence transformation I just invented. This transform is done by viewing the sequence as a stack in Forth or Factor (first ...
19
votes
20answers
2k views
Hunt for discount
Story
My local pizza delivery introduced new discount. You get 50% discount from every second item on your order.
But being greedy capitalists, they forgot to mention that they will rearrange items ...
23
votes
17answers
2k views
Show me the trajectory
Given a list of integers find the "trajectory" that results from indefinitely moving the instructed steps to the right (left if negative), wrapping if necessary, starting at the first ...
9
votes
7answers
738 views
Reverse cadaddadadaddddaddddddr [closed]
The Lisp language has a family of functions car, cdr, cadr, etc for accessing arrays. For ...
23
votes
26answers
1k views
Split into sublists of specified sizes
05AB1E has the £ builtin which, given a list of integers b and a string s, splits ...
18
votes
19answers
5k views
What's my PIN number?
My PIN number is 1077, but that's too difficult to remember. I know from muscle memory that it's a digit, followed by a different digit, then followed by two of the same digit, which is different to ...
21
votes
18answers
4k views
Build me a room
Related
A room, in the context of this challenge, is a multidimensional array where the elements on the "outside" are 1, to represent the walls, and all ...
6
votes
6answers
497 views
Group binary shapes together
Consider the following binary matrix:
$$\begin{matrix}
1 & 0 & 1 \\
1 & 0 & 0 \\
0 & 1 & 1
\end{matrix}$$
The (1-indexed) co-ordinates of the \$1\$s here are \$(1,1), (1,3), (2,...
22
votes
22answers
3k views
Longest Zero Sum Sub-array
Given an array of integers. Find out its longest sub-array (contiguous subsequence) whose sum is 0.
The sub-array for output may be an empty array.
Input
Input an array of integers.
Output
Output the ...
6
votes
6answers
377 views
Blinking Lighthouses – Founder's Day Upgrade
To celebrate the island's next Founder's Day, colored filters (fuchsia, chartreuse, and aquamarine*) have been installed in every lighthouse. All lighthouses begin operation with their fuchsia filter,...
5
votes
3answers
149 views
Is this an ordinal transform? [duplicate]
Related: What's my telephone number? which asks to calculate the terms of A000085, the number of possible ordinal transforms of length n.
Background
Ordinal transform is a transformation on an integer ...
23
votes
8answers
2k views
Blinking Lighthouses
Lighthouses on an island have blink codes that let ships know which lighthouse they are seeing. Input should be strings of S and L. Here is a (Python) example of codes for 4 lighthouses as a list of ...
29
votes
26answers
2k views
Recursive Z-matrix
Originally from a CMC I proposed for the last BMG event
Challenge
Given a non-negative integer \$n\$, create a 2D array of size \$2^n × 2^n\$ which is generated in the following manner:
Divide the ...
14
votes
10answers
1k views
How many bead arrangements on the abacus?
Your toy in this challenge is a special abacus of 4 rows and 8 positions per row. There's one bead on the first row, 2 beads on the 2nd row, 3 beads on the 3rd row and 4 beads on the 4th row. Beads on ...
1
vote
1answer
175 views
No of subsets of a given array such that their product is in the form of p1*p2*p3 [closed]
Given an array \$A\$ of size \$n\$.
You have to find the number of subsets such that their product is in the form of \$p_1 \times p_2 \times p_3 \dots\$
where \$p_1, p_2, p_3, \dots\$ are prime ...
29
votes
40answers
3k views
Is this a Permutation of 1..n
Input a non-empty array with \$n\$ positive integers. Test if the input array contains every integer in \$1\cdots n\$.
In case you prefer 0-indexed numbers, you may choose to input an array of non-...
1
vote
0answers
54 views
Reverse a sentence word by word [duplicate]
The setting
"Well I actually wrote the sql library they, the maintainers actually.."
"Right, but do you have any experience working with django?"
" ...no I don't use ...
30
votes
12answers
2k views
Is it a checkered tiling?
Background
A checkered tiling of a rectangular grid is a tiling using some polyominoes, where each region can be colored either black or white so that no two polyominoes sharing an edge has the same ...
14
votes
23answers
2k views
What's missing (aka the vanilla multiset difference challenge)
Write a program which takes two arrays of positive integers as input. One of them (your choice which) will have one item missing compared to the other. Your program must figure out what is missing.
...
27
votes
22answers
1k views
Consecutive Distance Rating
We'll call the consecutive distance rating of an integer sequence the sum of the distances between consecutive integers. Consider 2 9 3 6 8 1.
...
13
votes
7answers
1k views
A Cat’s Game to Claim
Intro
You like cats. Naturally, you like cat’s games in tic-tac-toe. So, you’ve come up with a little party trick.
You ask someone what square on the board they want you to make a move in. And you ask ...
18
votes
8answers
1k views
Generalised multi-dimensional chess knight's moves
Multi-dimensional chess is an extension of normal chess that is played on an 8x8x8x8... "board".
In normal 2D chess, a knight's move is a movement by a vector of \$ \begin{bmatrix} \pm 2 \\ \...
31
votes
48answers
2k views
Split a list at the second occurrence of the first element
Why should you golf in Haskell? Find out here. In that answer, Zgarb defines a task:
Let's define a function f that splits a list at the second occurrence of the ...
17
votes
14answers
991 views
Smallest slice of array containing a number of items
Take this array:
[1, 2, 6, 4, 4, 1, 0, 0, 2, 0, 4, 1, 4, 2, 4, 8, 1, 2, 4]
There are quite a few places where ...
26
votes
21answers
3k views
I'm Lazy*: Top-left align my text
* and don't have a word processor with top-left align support :D
Take several lines of input, with at least four unique characters of your choice including newline and space. The input can also be ...
