leetcode之Product of Array Except Self

product of array except self，这道题本身看上去不难，只是加了条件是要求O(n)，这就要求只能遍历一次，不能每次都乘一遍。我的做法是遍历一次，把非零的都乘起来，将0 的单独处理。代码如下：

class Solution(object):
    def productExceptSelf(self, nums):
        """
        :type nums: List[int]
        :rtype: List[int]
        """
        pro = 1
        a = []
        for i in nums:
        	if i != 0:
        		pro = pro * i
        	else:
        		a.append(0)
        b = []
        if len(a) > 1:
        	for i in nums:
        		b.append(0)
        elif len(a) == 1:
        	for i in nums:
        		if i == 0:
        			b.append(pro)
        		else:
        			b.append(0)
        else:
        	for i in nums:
        		b.append(pro / i)
        return b