leetcode283：移动零元素（move-zeroes）

### 问题描述：

Given an integer array nums, move all 0's to the end of it while maintaining the relative order of the non-zero elements.
Note that you must do this in-place without making a copy of the array.

Example 1:
Input: nums = [0,1,0,3,12]
Output: [1,3,12,0,0]

Example 2:
Input: nums = [0]
Output: [0]

Constraints:
1 <= nums.length <= 104
-231 <= nums[i] <= 231 - 1

Follow up: Could you minimize the total number of operations done?

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