You are given an integer array
nums and an integer target.You want to build an expression out of
nums by adding one of the symbols + and - before each integer in nums and then concatenating all the integers.- For example, if
nums = [2, 1], you can add a+before2and a-before1and concatenate them to build the expression+2-1.
Return the number of different expressions that you can build, which evaluates to
target.Examples
Example 1
Inputnums = [1,1,1,1,1], target = 3
Output5
ExplanationThere are 5 ways to assign symbols to make the sum of nums equal to 3:
-1 + 1 + 1 + 1 + 1 = 3
+1 - 1 + 1 + 1 + 1 = 3
+1 + 1 - 1 + 1 + 1 = 3
+1 + 1 + 1 - 1 + 1 = 3
+1 + 1 + 1 + 1 - 1 = 3
Example 2
Inputnums = [1], target = 1
Output1
Constraints
1 <= nums.length <= 20
0 <= nums[i] <= 1000
0 <= sum(nums[i]) <= 1000
-1000 <= target <= 1000