283. Move Zeroes

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.

Example:

Input: [0,1,0,3,12]
Output: [1,3,12,0,0]

Note:

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

要求不开额外数组内存，可以开两个变量，一个是统计0个个数，一个是当前数组不为0的位置到哪里了，每次不为零的数就往这个index移动，最后用统计出的0个个数往数组的最后补

class Solution(object):
    def moveZeroes(self, nums):
        """
        :type nums: List[int]
        :rtype: None Do not return anything, modify nums in-place instead.
        """
        zero_count = 0
        index = 0
        for i in range(len(nums)):
            if nums[i] == 0:
                zero_count += 1
            else:
                nums[index] = nums[i]
                index += 1
        for i in range(index, index + zero_count, 1):
            nums[i] = 0