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:
You must do this in-place without making a copy of the array. Minimize the total number of operations.
通过使用双指针, 遍历一次获得结果