152. Maximum Product Subarray

Given an integer array nums, find a contiguous non-empty subarray within the array that has the largest product, and return the product.

It is guaranteed that the answer will fit in a 32-bit integer.

A subarray is a contiguous subsequence of the array.

Example 1:

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2
3

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

Example 2:

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3

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

邊走邊找看過最大乘積。

# TC:O(n), TS:O(1)

class Solution:
    def maxProduct(self, nums: List[int]) -> int:
        res = max(nums)
        curMin, curMax = 1, 1
        
        for n in nums:
            if n == 0:
                curMin, curMax = 1, 1
                continue
            temp = curMax * n
            curMax = max(n, n * curMin, n * curMax)
            curMin = min(n, n * curMin, temp)
            res = max(res, curMax)
            
        return res

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