本次選擇的題目是

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.

For example, given nums = [0, 1, 0, 3, 12], after calling your
function, nums should be [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.

Solution：
利用雙指標的方法，一個指標忽視0，一個指標不斷往前，忽視0的指標利用不斷往前的指標將0替換到按順序的非0數。

class Solution {
public:
    void moveZeroes(vector<int>& nums) {
        int j = 0;
        // move all the nonzero elements advance
        for (int i = 0; i < nums.size(); i++) {
            if (nums[i] != 0) {
                nums[j++] = nums[i];
            }
        }
        for
 
 (;j < nums.size(); j++) {
            nums[j] = 0;
        }
    }
};