Combination Sum

class Solution {public:    vector<vector<int>>res;    vector<vector<int> > combinationSum(vector<int> &candidates, int target) {        vector<int>path;        combination(candidates,target,path,0);        return res;    }    void combination(vector<int>&candidates,int target,vector<int>&path,int sum)    {        if(target==sum)        {            res.push_back(path);            return ;        }        for(int i=0;i<candidates.size();i++)        {            if(candidates[i]+sum<=target&&(path.size()==0||path.size()!=0&&path[path.size()-1]<=candidates[i]))            {                path.push_back(candidates[i]);                combination(candidates,target,path,sum+candidates[i]);                path.pop_back();            }        }    }};