494. Target Sum

class Solution {
public:
    int findTargetSumWays(vector<int>& nums, int S) {
        findTarget(nums,0,0,S);
        return res;
    }
    void findTarget(vector<int>& nums,int index,int sum,int S){
        if(index == nums.size()){
            if(sum == S)
                res++;
            return;
        }
        findTarget(nums,index+1,sum + nums[index],S);
        findTarget(nums,index+1,sum - nums[index],S);
    }
    int res = 0;
};