gcj 2020 r1a

#include <bits/stdc++.h>
using namespace std ;

#define int long long

inline bool ok(string &a , string &b){
    //cout << b.substr(0,(int)a.size()) << " " << a << endl ;
    return b.substr(0,(int)a.size()) == a ;
}

void solve(int t){
    int n ;
    cin >> n ;
    string s[n] ;
    for(int i = 0 ; i < n ; i++){
        cin >> s[i] ;
    }
    map<int,set<string>> mp;
    vector<string> last ;
    for(int i = 0 ; i < n ; i++){
        int cnt = 0 ;
        string temp = "";
        for(int j = 0 ; j < s[i].size() ; j++){
            if(s[i][j] == '*'){
                mp[cnt++].insert(temp) ;
                temp = "";
            } else {
                temp += s[i][j] ;
            }
        }
        if(s[i].back() != '*') {
            reverse(temp.begin(),temp.end()) ;
            last.push_back(temp) ;
        }
    }
    string check = "" ;
    bool found = true ;
    for(auto j : mp[0]){
        if(j.size() > check.size()) {
            check = j ;
        }
        if(!ok(j,check)) found = false ;
    }
    for(auto j : mp[0]) if(!ok(j,check)) found = false ;
    string check2 = "";
    for(auto j : last){
        if(j.size() > check2.size()) {
            check2 = j ;
        }
    }
    for(auto j : last) if(!ok(j,check2)) found = false ;
    reverse(check2.begin(),check2.end()) ;
    string ans = "";
    if(found){
        for(auto i : mp){
            if(i.first)
            for(auto j : i.second){
                ans += j ;
            }
        }
        ans = check + ans + check2 ;
    } else {
        ans = "*";
    }
    cout << "Case #"<< t << ": " << ans << '\n' ;
}

int32_t main(){
    ios :: sync_with_stdio(0) ;
    cin.tie(0) ;
    int t ;
    cin >> t ;
    for(int i = 1 ; i <= t ; i++){
        solve(i) ;
    }
    return 0 ;
}