Question

It is a bit hard to describe what a i want so i start with and example:

Index   ArrayPos
1       0,0
2       1,0
3       0,1
4       1,1
5       2,0
6       2,1
7       2,2
8       0,2
9       1,2
10      1,2
11      3,0
12      3,1

and so on. Basically i want to fill the array not row by row or column by column but always the closest free place to 0,0 .

Would be great if duration of the algo would always be the same no matter wether if i want to get the array position for index 3 or 4237882348.

I tried some stuff with modulo but never got it.

Answer 1

If you don’t care about the order of x, y and y, x, then this should work for you:

let x = ceiling(sqrt(Index)) - 1
let y = ceiling((Index - x^2)/2) - 1
if Index is odd, swap x and y

With this, though 4,4 comes before 5,0, so it depends on the order you want when getting into the larger numbers you don’t have in your example…