Java: Interleaving multiple arrays into a single array

Question

I found similar question about interleaving two arraylists into one, but its in PHP. I was asked this question in interview as well but could\'nt solve it, came back to SO t

Answer 1

I've done up a small solution going on the assumption that you are talking about using the ArrayList (see my comment on the question). I may be oversimplifying the problem based on some of the responses here, but here goes anyway.

The below example takes a and b both of type ArrayList and interleaves them by inserting b[0] after a[0], b[1] after a[1] etc. This snippet of course naively assumes that a and b are of the same size as per your Edit v1.0. It also does not create a new ArrayList as per your Edit v2.0.

//a and b are of type ArrayList
for (int i = a.size(); i > 0; i--)
{
    a.add(i, b.get(i - 1));
}

No matter what happens if you are combining the ArrayLists you're going to have twice the size.