[Leetcode] Combination Sum III

public class Solution {
public void dp(List<List<Integer>> list, List<Integer> listone, int tmpsum, int start, int k, int target){
if(tmpsum==target&&listone.size()==k){
List<Integer> newlist = new LinkedList<Integer>();
newlist.addAll(listone);
list.add(newlist);
return;
}
if(listone.size()==k) return;
//listone.add(start);
for(int s=start;s<=9;s++){
listone.add(s);
dp(list,listone,tmpsum+s,s+1,k,target);
listone.remove(listone.size()-1);
}
//listone.remove(listone.size()-1);
return;
}
public List<List<Integer>> combinationSum3(int k, int n) {
List<List<Integer>> list = new LinkedList<List<Integer>>();
List<Integer> listone = new LinkedList<Integer>();
for(int i=1;i<=9;i++){
listone.add(i);
dp(list,listone,i,i+1,k,n);
listone.remove(listone.size()-1);
}
return list;
}
}