283. 移动零

思路：

双指针（快慢指针）。

代码一：

 1 class Solution(object):
 2     def moveZeroes(self, nums):
 3         """
 4         :type nums: List[int]
 5         :rtype: None Do not return anything, modify nums in-place instead.
 6         """
 7         j = 0
 8         for i in range(len(nums)):
 9             if nums[i] != 0:
10                 nums[j] = nums[i]
11                 j += 1
12         while j < len(nums):
13             nums[j] = 0
14             j += 1

代码二：

 1 class Solution(object):
 2     def moveZeroes2(self, nums):
 3         """
 4         :type nums: List[int]
 5         :rtype: None Do not return anything, modify nums in-place instead.
 6         """
 7         j = 0
 8         for i in range(len(nums)):
 9             if nums[i] != 0:
10                 nums[i], nums[j] = nums[j], nums[i]
11                 j += 1