3. Given an array starting from 1 to 2^n, [1,2,3,4], transform the array such that when you split the array in half, the left side goes on top of the right, repeat this until the left side has a length of 1. [1,2,3,4] => [1,2][3,4] => [1][3][2][4] => [1,3,2,4].