PAT 1077

簡單題，用C++寫了... 

需要注意的是，cin了之後不會把 吃掉，需要再getchar一次才能夠吃掉 ，然後接着geline才正確

感覺沒什麼美感... 

#include <vector>
#include <iostream>
#include <string>
#include <algorithm>
#include <limits>
#include <cstdio>

using namespace std;

int main(){
    int N;
    cin >> N;
    getchar();

    vector<string> lines;
    int shortest = 0x7fffffff;
    for (int i = 0; i < N; i++){
        string str;
        getline(cin, str);

        if (str.size() < shortest)
            shortest = str.size();

        lines.push_back(str);
    }

    int common_len = 0;
    for (int i = 0; i < shortest; i++){
        char ch = lines[0][lines[0].size() - i - 1];

        int cnt = 1;
        for (int j = 1; j < lines.size(); j++){
            string cur_str = lines[j];
            if (cur_str[cur_str.size() - i - 1] != ch)
                break;
            cnt++;
        }

        if (cnt == lines.size())
            common_len++;
        else
            break;
    }

    if (common_len == 0)
        cout << "nai" << endl;
    else{
        string res = lines[0].substr(lines[0].size() - common_len, lines[0].size());
        cout << res << endl;
    }

    return 0;
}