【双指针】283. 移动零

题目
两种方法时间复杂度相同都是O(n)，方法2操作更少一些。

Python

class Solution:
    def moveZeroes(self, nums: List[int]) -> None:
        """
        Do not return anything, modify nums in-place instead.
        """
        left = right = 0
        n = len(nums)
        while right < n:
            if nums[right] != 0:
                nums[left] = nums[right]
                left += 1
            right += 1
        
        while left < n:
            nums[left] = 0
            left += 1

Java

1.解法1: 有优化空间

class Solution {
    public void moveZeroes(int[] nums) {
        int slow = 0, fast = 0;
        while (fast < nums.length) {
            if (nums[fast] != 0) {
                if (slow == fast) {
                    ++slow;
                    ++fast;
                } else {
                    nums[slow++] = nums[fast++];
                }
            } else {
                ++fast;
            }
        }
        while (slow < nums.length) {
            nums[slow++] = 0;
        }
    }
}

解法2：最佳写法

class Solution {
    public void moveZeroes(int[] nums) {
        int slow = 0, fast = 0;
        while (fast < nums.length) {
            if (nums[fast] != 0) {
                if (nums[slow] != 0) {
                    ++slow;
                    ++fast;
                } else {
                    nums[slow++] = nums[fast];
                    nums[fast++] = 0;
                }
            } else {
                ++fast;
            }
        }
    }
}