Given a collection of integers that might contain duplicates, nums, return all possible subsets.
Note:
- Elements in a subset must be in non-descending order.
- The solution set must not contain duplicate subsets.
For example,
If nums = [1,2,2]
, a solution is:
[
[2],
[1],
[1,2,2],
[2,2],
[1,2],
[]
]
- public class Solution {
- public List<List<Integer>> subsetsWithDup(int[] nums) {
- List<List<Integer>> res = new ArrayList<List<Integer>>();
- if(nums.length==0) return res;
- Arrays.sort(nums);
- helper(nums, 0, new ArrayList<Integer>(), res);
- return res;
- }
-
- public void helper(int[] nums, int level, List<Integer> item, List<List<Integer>> res) {
- res.add(new ArrayList<Integer>(item));
- for(int i=level;i<nums.length;i++){
- item.add(nums[i]);
- helper(nums,i+1,item,res);
- item.remove(item.size()-1);
-
- while(i<(nums.length-1)&&nums[i]==nums[i+1]) {
- i++;
- }
- }
- }
- }
原文链接http://blog.youkuaiyun.com/crazy__chen/article/details/46434415