方法

    1. class Solution {
    2. public:
    3.     vector<vector<int>>results;
    4.     vector<int>result;
    5.     vector<vector<int>> subsetsWithDup(vector<int>& nums) {
    6.         sort(nums.begin(),nums.end());
    7.         results.emplace_back();
    8.         dfs(nums,0);
    9.         return results;
    10.     }
    11.     void dfs(vector<int>& nums,int id){
    12.         if(id>nums.size()){
    13.             return;
    14.         }
    15.         for(int i=id;i<nums.size();i++){
    16.             if(i>id&&nums[i]==nums[i-1]){
    17.                 continue;
    18.             }
    19.             result.emplace_back(nums[i]);
    20.             results.emplace_back(result);
    21.             dfs(nums,i+1);
    22.             result.pop_back();
    23.         }
    24.     }
    25. };