LeetCode Subsets II

Given a collection of integers that might contain duplicates, S, 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 S = [1,2,2], a solution is:

[
  [2],
  [1],
  [1,2,2],
  [2,2],
  [1,2],
  []
]

包含重复元素的集合，求子集。同Subsets，只是添加进List时判断是否已经存在

public class Solution {
    public ArrayList<ArrayList<Integer>> subsetsWithDup(int[] num) {
        Arrays.sort(num);
        ArrayList<ArrayList<Integer>> result=new ArrayList<ArrayList<Integer>>();
        ArrayList<Integer> tmp=new ArrayList<Integer>();
        result.add(tmp);
        for(int i=0;i<num.length;i++)
        {
        	int len=result.size();
        	for(int j=0;j<len;j++)
        	{
        		tmp.clear();
        		tmp=(ArrayList<Integer>) result.get(j).clone();
        		tmp.add(num[i]);
        		if(!result.contains(tmp))  //判断是否已经存在
        			result.add((ArrayList<Integer>) tmp.clone());
        	}
        }
        return result;
    }
}