39. Combination Sum

简单常规题，回朔

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