#+PROPERTY: STUDY_DECK_02 * TODO 0494. Target Sum :medium: :PROPERTIES: :NEETCODE: [[file:../../roadmap.org::*0494. Target Sum][0494. Target Sum]] :END: 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 concatenate all the integers. - For example, if ~nums = [2, 1]~, you can add a ~'+'~ before ~2~ and a ~'-'~ before ~1~ and concatenate them to build the expression ~"+2-1"~. Return the number of different *expressions* that you can build, which evaluates to ~target~. *Example 1:* #+begin_src Input: nums = [1,1,1,1,1], target = 3 Output: 5 Explanation: There are 5 ways to assign symbols to make the sum of nums be target 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 #+end_src *Example 2:* #+begin_src Input: nums = [1], target = 1 Output: 1 #+end_src *Constraints:* - ~1 <= nums.length <= 20~ - ~0 <= nums[i] <= 1000~ - ~0 <= sum(nums[i]) <= 1000~ - ~-1000 <= target <= 1000~ ** TODO Approach Write your approach here. ** TODO Python #+begin_src python class Solution: def findTargetSumWays(self, nums: List[int], target: int) -> int: #+end_src ** TODO C++ #+begin_src cpp class Solution { public: int findTargetSumWays(vector& nums, int target) { } }; #+end_src