Subsets II

Source

• lintcode: Subsets II

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],
  []
]

Java

public class Solution {
    public List<List<Integer>> subsetsWithDup(int[] nums) {
        List<List<Integer>> result = new ArrayList<List<Integer>>();
        if(nums.length==0) return result;
        Arrays.sort(nums);
        dfs(nums, 0, new ArrayList<Integer>(), result);
        return result;
    }

    public void dfs(int[] nums, int index, List<Integer> path, List<List<Integer>> result){
        result.add(new ArrayList<Integer>(path));

        for(int i=index; i<nums.length; i++){
            if(i>index && nums[i]==nums[i-1]) continue;
            path.add(nums[i]);
            dfs(nums, i+1, path, result);
            path.remove(path.size()-1);
        }
    }
}