leetcode-152-乘积最大子序列

题目描述：

方法一：动态规划

class Solution:
    def maxProduct(self, nums: List[int]) -> int:
        ret,up,down=nums[0],nums[0],nums[0] 
        for n in nums[1:]: 
            if n>=0: 
                up,down=max(up*n,n),min(down*n,n) 
            else: 
                up,down=max(down*n,n),min(up*n,n) 
            ret=max(ret,up) 
        return ret