539. Move Zeroes

題目：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.

Notice
You must do this in-place without making a copy of the array.
Minimize the total number of operations.

思路：
兩個指針
left 指向目前最後一個非0的數
right 往後找非 0 ，找到後和 left++ 交換

代碼：

public:
    /**
     * @param nums: an integer array
     * @return: nothing
     */
    void moveZeroes(vector<int> &nums) {
        // write your code here
        int left = 0;
        int right = 0;
        
        //left 指向目前最後一個非0的數
        //right 往後找非 0 ，找到後和 left++ 交換
        
        while( right < nums.size()){
            if(nums[right]){
                swap(nums[left++], nums[right]);
            }
            right++;
        }
    }
};