[2018-Interview] Move Zeros

Original question: https://leetcode.com/problems/move-zeroes/description/

My answer:

class Solution {
    public void moveZeroes(int[] nums) {
        if (nums == null || nums.length < 1) {
            return;
        }
        int count = 0;
        for (int i = 0; i < nums.length; i ++) {
            if (nums[i] == 0) {
                count ++;
                continue;
            }
            nums[i - count] = nums[i];
        }
        // clear the last number of #{count} elements to 0
        for (int i = nums.length - 1; i > nums.length - 1 - count; i --) {
            nums[i] = 0;
        }
    }
}

Better answer: this method actually is using variable "left" to keep 0s position, and "right" to keep non-0 position. "right" is always increasing, while "left" doesn't change if 0 is encountered.

class Solution {
public:
    void moveZeroes(vector<int>& nums) {
        int left = 0, right = 0;
        while (right < nums.size()) {
            if (nums[right]) {
                swap(nums[left++], nums[right]);
            }
            ++right;
        }
    }
};