216. Combination Sum III

class Solution {
private:
void search(vector<vector<int>> &ret,vector<int> &cur,int start,int k,int target)
{
if(cur.size()>=k)
return;
for(int i=start;i<=9;i++)
{
if(cur.size()==k-1&&i==target)
{
cur.push_back(i);
ret.push_back(cur);
cur.pop_back();
}
else
{
cur.push_back(i);
search(ret,cur,i+1,k,target-i);
cur.pop_back();
}

}
}
public:
vector<vector<int>> combinationSum3(int k, int n) {
vector<vector<int>> ret;
vector<int>temp;
search(ret,temp,1,k,n);
return ret;
}
};