283. Move Zeroes

https://leetcode.com/problems/move-zeroes/

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.
Example:
Input: [0,1,0,3,12]
Output: [1,3,12,0,0]
Note:
  1. You must do this in-place without making a copy of the array.
  2. Minimize the total number of operations.
--
Time - O(n)
Space - O(1)
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