# 1746. Maximum Subarray Sum After One Operation

<https://leetcode.com/problems/maximum-subarray-sum-after-one-operation>

## Description

You are given an integer array `nums`. You must perform **exactly one** operation where you can **replace** one element `nums[i]` with `nums[i] * nums[i]`.&#x20;

Return *the **maximum** possible subarray sum after **exactly one** operation*. The subarray must be non-empty.

**Example 1:**

```

**Input:** nums = [2,-1,-4,-3]
**Output:** 17
**Explanation:** You can perform the operation on index 2 (0-indexed) to make nums = [2,-1,**16**,-3]. Now, the maximum subarray sum is 2 + -1 + 16 = 17.
```

**Example 2:**

```

**Input:** nums = [1,-1,1,1,-1,-1,1]
**Output:** 4
**Explanation:** You can perform the operation on index 1 (0-indexed) to make nums = [1,**1**,1,1,-1,-1,1]. Now, the maximum subarray sum is 1 + 1 + 1 + 1 = 4.
```

**Constraints:**

* `1 <= nums.length <= 105`
* `-104 <= nums[i] <= 104`

## ac

```java
```