Given an array
nums, write a function to move all
0's to the end of it while maintaining the relative order of the non-zero elements.
nums = [0, 1, 0, 3, 12], after calling your function,
nums should be
[1, 3, 12, 0, 0].
You must do this in-place without making a copy of the array.
Minimize the total number of operations.