#1856

Maximum Subarray Min-Product

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array · stack · monotonic stack · prefix sum

Description

The min-product of an array is equal to the minimum value in the array multiplied by the array's sum.

- For example, the array [3,2,5] (minimum value is 2) has a min-product of 2 * (3+2+5) = 2 * 10 = 20.

Given an array of integers nums, return the maximum min-product of any non-empty subarray of nums. Since the answer may be large, return it modulo 10⁹ + 7.

Note that the min-product should be maximized before performing the modulo operation. Testcases are generated such that the maximum min-product without modulo will fit in a 64-bit signed integer.

A subarray is a contiguous part of an array.

Example 1:

Input: nums = [1,2,3,2]

Output: 14

Explanation: The maximum min-product is achieved with the subarray [2,3,2] (minimum value is 2).

2 * (2+3+2) = 2 * 7 = 14.

Example 2:

Input: nums = [2,3,3,1,2]

Output: 18

Explanation: The maximum min-product is achieved with the subarray [3,3] (minimum value is 3).

3 * (3+3) = 3 * 6 = 18.

Example 3:

Input: nums = [3,1,5,6,4,2]

Output: 60

Explanation: The maximum min-product is achieved with the subarray [5,6,4] (minimum value is 4).

4 * (5+6+4) = 4 * 15 = 60.

Solution