[Leetcode] Combination Sum II

 1 import java.util.*;
 2 
 3 public class Solution {
 4     private void dp(Vector<Integer> num, Vector<Integer> count,int index, int target, int tmpsum, 
 5     List<Integer> tmplist,List<List<Integer> > lists){
 6         if(tmpsum==target){
 7             List<Integer> l = new LinkedList<Integer>();
 8             l.addAll(tmplist);
 9             lists.add(l);
10             return;
11         }
12         if(index==num.size()||tmpsum>target) return;
13         int tmpcount=count.get(index);
14         int number=num.get(index);
15         for(int i=0;i<tmpcount;i++){
16             tmplist.add(number);
17             dp(num,count,index+1,target,tmpsum+(i+1)*number,tmplist,lists);
18         }
19         //because there is only one tmplist, when all the cases which contain number 
20         //has been tried, we try the one which ignore it.
21         for(int i=0;i<tmpcount;i++){
22             tmplist.remove(tmplist.size()-1);
23         }
24         dp(num,count,index+1,target,tmpsum,tmplist,lists);
25     }
26     public List<List<Integer>> combinationSum2(int[] candidates, int target) {
27         Arrays.sort(candidates);
28         /////the code below is to statistic the unique numbers and the number 
29         /////of each of them
30         Vector<Integer> num =new Vector<Integer>();
31         Vector<Integer> count =new Vector<Integer>();
32         int pre=candidates[0];
33         int tmpcount=1;
34         for(int i=1;i<candidates.length;i++){
35             if(candidates[i]==pre){
36                 tmpcount++;
37             }else{
38                 num.add(pre);
39                 count.add(tmpcount);
40                 pre=candidates[i];
41                 tmpcount=1;
42             }
43         }
44         num.add(pre);
45         count.add(tmpcount);
46         //to call the method above
47         List<Integer> tmplist =new LinkedList<Integer>();
48         List<List<Integer> > lists =new LinkedList<List<Integer> >();
49         dp(num,count,0,target,0,tmplist,lists);
50         return lists;
51     }
52 }