LeetCode 19 组合总和

class Solution {
public:
    vector<vector<int>> res;
    vector<int> path;
    int sum = 0;

    void dfs(int start, vector<int>& candidates, int target) {
        if (sum > target) return;


        if (sum == target) {
            res.push_back(path);
            return;
        }

        for (int i = start; i < candidates.size(); i ++) {
            path.push_back(candidates[i]);
            sum += candidates[i];
            dfs(i, candidates, target); //i不用加1表示可以取到这个数
            path.pop_back();
            sum -= candidates[i];
        }
    }

    vector<vector<int>> combinationSum(vector<int>& candidates, int target) {
        dfs(0, candidates, target);

        return res;
    }
};