[leetcode]Subsets II

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],
  []
]

算法思路：

跟[leetcode]Subsets 相比，只是多了一步去重复，其余木有区别，直接暴力。

代码如下：

public class Solution { 
    List<List<Integer>> res = new ArrayList<List<Integer>>();
    public List<List<Integer>> subsetsWithDup(int[] num) {
        if(num == null || num.length == 0) return res;
        Arrays.sort(num);
        List<Integer> list = new ArrayList<Integer>();
        dfs(list,0,0,num);
        return res;
    }
    private void dfs(List<Integer> list,int k ,int count,int[] num){
        if(count <= num.length){
            res.add(new ArrayList<Integer>(list));
        }else{
            return;
        }
        for(int i = k ; i < num.length; i++){
            list.add(num[i]);
            dfs(list,i + 1,count+1,num);
            list.remove(list.size() - 1);
            while(i < num.length - 1 && num[i] == num[i + 1]) i++;
        }
    }
}