【LeetCode494】目标和（暴搜dfs或dp）

class Solution {
    int method_num = 0;
public:
    int findTargetSumWays(vector<int>& nums, int target) {
        dfs(nums, 0, target, 0);
        return method_num;
    }
    void dfs(vector<int>& nums, int k, int target, int cur_res){
        if(k == nums.size()){
            if(cur_res == target){
                method_num += 1;
            }
            return;
        }
        dfs(nums, k + 1, target, cur_res + nums[k]);
        dfs(nums, k + 1, target, cur_res - nums[k]);
    }
};