You are given an integer array nums and an integer target.
Return the number of different expressions you can build by adding either a plus or minus sign before each number so the total equals target.
Examples
Input: nums = [1,1,1,1,1], target = 3 Output: 5
Input: nums = [1], target = 1 Output: 1
Constraints
- 1 <= nums.length <= 20
- 0 <= nums[i] <= 1000
- -1000 <= target <= 1000