code jam 2020 round 1A Pattern Matching

//code jam 2020 round 1A Pattern Matching
#include<bits/stdc++.h>
using namespace std;

string arr[50];
string prefix, suffix;
bool have_ans;

bool check(string a, string b){
    for(int i = 0; i < min(a.size(), b.size()); ++i){
        if(a[i] != b[i])return false;
    }
    return true;
}

void update(string s){
    string pre = "", suf = "";
    for(int i = 0; i < s.size() && s[i] != '*'; ++i)pre += s[i];
    for(int i = s.size()-1; i >= 0 && s[i] != '*'; --i)suf += s[i];
    if(check(prefix, pre) && check(suffix, suf)){
        if(pre.size() > prefix.size())prefix = prefix = pre;
        if(suf.size() > suffix.size())suffix = suffix = suf;
    }else have_ans = false;
}

int main(){
    int t;
    cin >> t;
    for(int c = 1; c <= t; ++c){
        prefix = suffix = "";
        have_ans = 1;
        int n;
        cin >> n;
        for(int i = 0; i < n; ++i){
            cin >> arr[i];
            update(arr[i]);
            //cout << prefix << ' ' << suffix << ' ' << have_ans << '\n';
        }
        cout << "Case #" << c << ": ";
        if(!have_ans)cout << '*';
        else{
            cout << prefix;
            for(int i = 0; i < n; ++i){
                for(int j = 0; j < arr[i].size(); ++j){
                    if(arr[i][j] != '*')cout << arr[i][j];
                }
            }
            for(int i = suffix.size()-1; i >= 0; --i)cout << suffix[i];
        }
        cout << endl;
    }
    return 0;
}