Given a collection of integers that might contain duplicates, S, return all possible subsets.
Note:
For example,
If S = [1,2,2], a solution is:
[ [2], [1], [1,2,2], [2,2], [1,2], [] ]
Solution:
1 public class Solution { 2 public List<List<Integer>> subsetsWithDup(int[] num) { 3 Arrays.sort(num); 4 List<List<Integer>> result = new ArrayList<List<Integer>>(); 5 List<Integer> al = new ArrayList<Integer>(); 6 dfs(result, al, num, 0); 7 return result; 8 } 9 10 private void dfs(List<List<Integer>> result, List<Integer> al, int[] s, 11 int start) { 12 // TODO Auto-generated method stub 13 result.add(new ArrayList<Integer>(al)); 14 for (int i = start; i < s.length; ++i) { 15 al.add(s[i]); 16 dfs(result, al, s, i+1); 17 al.remove(al.size()-1); 18 while((i+1<s.length)&&(s[i]==s[i+1])) 19 ++i; 20 } 21 } 22 }
原文：http://www.cnblogs.com/Phoebe815/p/4094064.html