LeetCode: 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.

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

class Solution {
public:
    void moveZeroes(vector<int>& nums) {
        int cnt = 0;
        int idx = 0, len = nums.size();
        for (int i = 0; i < len; i++) {
            if (nums[i] == 0) {
                cnt++;
            } else {
                swap(nums[idx], nums[i]);
                idx++;
            }
        }

        while (cnt) {
            nums[len - cnt--] = 0;
        }
    }
};