152 Maximum Product Subarray (a new way to solve DP!!)

def maxProduct(self, nums):
        if len(nums) == 0:
            return []
        elif len(nums) == 1:
            return nums[0]
        else:
            result,product_max,product_min = nums[0],nums[0],nums[0]
            for i in range(1,len(nums)): 
                if nums[i] < 0: #if we encounter a negative element,then previous smallest product becomes biggest and vice versa.
                    product_max,product_min = product_min,product_max
                product_max = max(product_max*nums[i],nums[i]) #product_max*nums[i] bigger then we let subarray continue growing, 
 otherwise we form a new subarray containing only one element !(the principle is make sure we contain nums[i])
                product_min = min(product_min*nums[i],nums[i])
                result = max(result,product_max)
        return result