[Leetcode] Combination Sum III

 1 public class Solution {
 2     public void dp(List<List<Integer>> list, List<Integer> listone, int tmpsum, int start, int k, int target){
 3         if(tmpsum==target&&listone.size()==k){
 4             List<Integer> newlist = new LinkedList<Integer>();
 5             newlist.addAll(listone);
 6             list.add(newlist);
 7             return;
 8         }
 9         if(listone.size()==k) return;
10         //listone.add(start);
11         for(int s=start;s<=9;s++){
12             listone.add(s);
13             dp(list,listone,tmpsum+s,s+1,k,target);
14             listone.remove(listone.size()-1);
15         }
16         //listone.remove(listone.size()-1);
17         return;
18     }
19     public List<List<Integer>> combinationSum3(int k, int n) {
20         List<List<Integer>> list = new LinkedList<List<Integer>>();
21         List<Integer> listone = new LinkedList<Integer>();
22         for(int i=1;i<=9;i++){
23             listone.add(i);
24             dp(list,listone,i,i+1,k,n);
25             listone.remove(listone.size()-1);
26         }
27         return list;
28     }
29 }