题解 | #没有重复项数字的所有排列#

class Solution {
public:
    void function(vector<int> &num, vector<int> &ans, vector<vector<int>> &res, vector<bool>& flag) {
        if(ans.size() == num.size()) {
            res.push_back(ans);
            return;
        }
        for(int i = 0; i < num.size(); i++) {
            if(!flag[i]) {
                flag[i] = true;
                ans.push_back(num[i]);
                function(num, ans, res, flag);
                ans.pop_back();
                flag[i] = false;
            }
        }
    }
    vector<vector<int> > permute(vector<int> &num) {
        vector<vector<int>> res;
        int size = num.size();
        if(size == 0)
            return res;
        sort(num.begin(), num.end());
        vector<int> ans;
        vector<bool> flag(num.size(), false);
        function(num, ans, res, flag);
        return res;
    }
};