C++ 代码

class Solution {
public:
    vector<vector<int>> ans;
    vector<int> path;
    vector<bool> st;
    void dfs(vector<int> & nums,int u,int start)
    {
        if(u==nums.size())
        {
            ans.push_back(path);
            return ;
         }
        for(int i=start;i<path.size();i++)
        {
            if(!st[i])
            {
                st[i]=1;
            path[i]=nums[u];
            dfs(nums,u+1,u+1<nums.size()&& nums[u+1]==nums[u]?i+1:0);
                st[i]=false;

            }
        }

    }

    vector<vector<int>> permuteUnique(vector<int>& nums) {
        int n=nums.size();
        path=vector<int>(n);
        st=vector<bool>(n);
        sort(nums.begin(),nums.end());
        dfs(nums,0,0);
        return ans;

    }
};