题解 | #有重复项数字的全排列#

class Solution {
public:
    vector<vector<int> > permuteUnique(vector<int> &num) {
        vector<vector<int>> res;
        vector<int> path;
        vector<bool> used(num.size(), false);
        sort(num.begin(), num.end());
        dfs(num, res, path, used);
        return res;
    }
    void dfs(vector<int>& num, vector<vector<int>>& res, vector<int>& path, vector<bool>& used){
        if(path.size()==num.size()){
            res.push_back(path);
            return;
        }
        for(int i=0; i<num.size(); i++){
            if(i>0 && num[i-1]==num[i] && used[i-1]==true){
                continue;
            }
            if(used[i]==false){
                path.push_back(num[i]);
                used[i] = true;
                dfs(num, res, path, used);
                used[i] = false;
                path.pop_back();
            }
        }
    }
};