LeetCode/152_Maximum_Product_Subarray.py at main · AnmolPatel20/LeetCode · GitHub

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"""
Given an integer array nums, find a subarray that has the largest product, and return the product.

The test cases are generated so that the answer will fit in a 32-bit integer.

Note that the product of an array with a single element is the value of that element.


Example 1:

Input: nums = [2,3,-2,4]
Output: 6
Explanation: [2,3] has the largest product 6.
Example 2:

Input: nums = [-2,0,-1]
Output: 0
Explanation: The result cannot be 2, because [-2,-1] is not a subarray.


Constraints:

1 <= nums.length <= 2 * 104
-10 <= nums[i] <= 10
The product of any subarray of nums is guaranteed to fit in a 32-bit integer.

"""

class Solution:
    def maxProduct(self, nums: List[int]) -> int:
        n = len(nums)
        leftProduct = 1
        rightProduct = 1
        ans = nums[0]

        for i in range(n):
            leftProduct = 1 if leftProduct == 0 else leftProduct
            rightProduct = 1 if rightProduct == 0 else rightProduct

            leftProduct *= nums[i] #prefix product
            rightProduct *= nums[n-1-i] #suffix product

            ans = max(ans , leftProduct , rightProduct)

        return ans