leetcode -39组合总数

class Solution {
public:
    vector<vector<int>> res;
    vector<int> temp; 
    vector<vector<int>> combinationSum(vector<int>& candidates, int target) {
    dfs(candidates,0,target,0);
    return res;
    }
    void dfs(vector<int> can,int sum,int tag,int start)
    {
        if(sum>tag)return;
        else if(sum==tag)
        {
        res.push_back(temp);
         return;}
        else 
        for(int i=start;i<can.size();i++)
        {
            temp.push_back(can[i]);
            dfs(can,sum+can[i],tag,i);
            temp.pop_back();
        }
    }
};