Given an integer array nums, return an array answer where answer[i] is the product of every element of nums except nums[i].
The answer is guaranteed to fit in a 32-bit integer. Solve it without using the division operator and aim for O(n) time.
[1,2,3,4][-1,1,0,-3,3][2,3][0,0][1,0][5,1,4,2]