A subarray of a 0-indexed integer array is a contiguous non-empty sequence of elements within an array.
The alternating subarray sum of a subarray that ranges from index i to j (inclusive, 0 <= i <= j < nums.length) is nums[i] - nums[i+1] + nums[i+2] - ... +/- nums[j].
Given a 0-indexed integer array nums, return the maximum alternating subarray sum of any subarray of nums.
Example 1:
Input: nums = [3,-1,1,2] Output: 5 Explanation: The subarray [3,-1,1] has the largest alternating subarray sum. The alternating subarray sum is 3 - (-1) + 1 = 5.
Example 2:
Input: nums = [2,2,2,2,2] Output: 2 Explanation: The subarrays [2], [2,2,2], and [2,2,2,2,2] have the largest alternating subarray sum. The alternating subarray sum of [2] is 2. The alternating subarray sum of [2,2,2] is 2 - 2 + 2 = 2. The alternating subarray sum of [2,2,2,2,2] is 2 - 2 + 2 - 2 + 2 = 2.
Example 3:
Input: nums = [1] Output: 1 Explanation: There is only one non-empty subarray, which is [1]. The alternating subarray sum is 1.
Constraints:
1 <= nums.length <= 105-105 <= nums[i] <= 105