字符串的排列

class Solution {
public:
    vector<string> Fun(string input){
        vector<string> tmp;

        //    tmp.insert(tmp.end(), input.begin(), input.end());
        tmp.push_back(input);
        if(idx >= input.length()-1)
            return tmp;
        int k = 0;
        while(k < 1){
            idx ++;
            vector<string> tmp_out = Fun(input);
            //tmp.insert(tmp.end(), tmp_out.begin(), tmp_out.end());
            tmp = tmp_out;
            idx --;
            string str = input;
        for(int i = idx; i < idx +1; i++){
            for(int j = i +1; j < str.length(); j++){
                if(str[i] != str[j]){
                    char center;
                    center = str[i];
                    str[i] = str[j];
                    str[j] = center;
                    //tmp.push_back(str);
                    idx++;
                    vector<string> in_tmp = Fun(str);
                    tmp.insert(tmp.end(), in_tmp.begin(), in_tmp.end());
                    idx --;
                    str[j] = str[i];
                    str[i] = center;
                }
            }
        }
            k ++;
        }
        //idx ++
        //vector<string> output = Fun(tmp);
        //tmp.insert(tmp.end(), output.begin(), output.end());
        return tmp;

    }
    vector<string> Permutation(string str) {
        if(str.length() == 0)
            return vector<string>();
        vector<string> output = Fun(str);
        sort(output.begin(), output.end(), [](string a, string b) -> bool{
            //cout << a << " " << b << endl;
            for(int i = 0; i < a.length(); i++){
                //cout << int(a[i]) << " " << int(b[i]) << endl;
                if((int(a[i]) - int(b[i])) > 0)
                    return false;
                else if((int(a[i]) - int(b[i])) < 0){
                    return true;
                }
            }
            return true;
        });
        //tmp.insert(tmp.end(), output.begin(), output.end());
        return output;
    }
private:
    int idx = 0;
};

 

来源：https://blog.csdn.net/perfects110/article/details/99691610