브라이언의_고민.cpp

#include <string>
#include <cctype>
#include <vector>
#include <iostream>
using namespace std;
const string ivd = "invalid";
string rule1(string str){
    string ret;
    if(str.size()<3) return "-1";
    char c = str[1];
    bool ok=0;
    for(int i=0;i<str.size();i++){
        if(islower(str[i])) ok=1;
        if(i%2==0){
            if(islower(str[i])) return "-1";
            ret+=str[i];
        }else{
            if(c!=str[i]) return "-1";
        }
    }
    if(!ok) return "-1";
    return ret;
}
string allUpper(string str){
    string ret;
    for(auto c : str){
        if(!isupper(c)) return "-1";
        ret+=c;
    }
    return ret;
}
string solution(string sentence) {
    vector<bool> used(26,0);
    string answer = "";
    int it=0;
    while(!sentence.empty()){
        string ret;
        vector<int> pos;
        if(islower(sentence[0])){
            if(used[sentence[0]-'a']) return ivd;
            used[sentence[0]-'a']=1;
            for(int i=0;i<sentence.size();i++){
                if(sentence[i]==sentence[0]) {
                    pos.push_back(i);
                }
            }
            if(pos.size()!=2) return ivd;

            string center = sentence.substr(1,pos.back()-1);
            if(center=="") return ivd;
            ret = rule1(center);
            string target;
            if(ret=="-1") {
                ret=allUpper(center);
                if(ret=="-1"){
                    return ivd;
                }
            }else{
                if(used[sentence[2]-'a']) return ivd;
                used[sentence[2]-'a']=1;
            }
            sentence = sentence.substr(pos.back()+1);
        }else{
            if(sentence.size()==1 || isupper(sentence[1])){
                ret=sentence[0];
                sentence=sentence.substr(1);
            }else{
                for(int i=0;i<sentence.size();i++){
                    if(sentence[1]==sentence[i]) pos.push_back(i); 
                }

                if(pos.size()!=2){
                    if(pos.back()==sentence.size()-1) return ivd;
                    if(islower(sentence[pos.back()+1])) return ivd;
                    string center = sentence.substr(0,pos.back()+2);
                    ret=rule1(center);
                    if(ret=="-1") return ivd;
                    if(used[sentence[1]-'a']) return ivd;
                    used[sentence[1]-'a']=1;
                    sentence=sentence.substr(pos.back()+2);
                }else{
                    ret=sentence[0];
                    sentence=sentence.substr(1);
                }   
            }
        }
        answer+=ret+" ";
    }
    answer.pop_back();
    return answer;
}