class Solution {
    public void moveZeroes(int[] nums) {
        int l = 0;//慢指针但先走

        for (int r = 0; r < nums.length; r++) {//快指针，遍历次数
            if (nums[r] == 0) 
                continue;//l比r先到，在此处定住l，r继续移动
            int t = nums[l];
            nums[l] = nums[r];
            nums[r] = t;
            l++;
        }
    }
}