水平扫描

import java.util.Scanner;  

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int N = scanner.nextInt();
        String[] strings = new String[N];
        for (int i = 0; i < N; i++)
            strings[i] = scanner.next();
        scanner.close();
        for (String s : strings)
            System.out.println(unique(s, strings));
    }
        //返回字符串s在字符串数组strings中最短唯一前缀
    private static String unique(String s, String[] strings) {
        String prefix = s.substring(0, 1);//前缀初始为首字符
        for (String single : strings) {
            if (single.equals(s))//跳过字符串s本身
                continue;
            while (single.indexOf(prefix) == 0 && prefix.length() < s.length()) //字符串single与字符串s具有相同的前缀prefix，前缀需要往后延长
                prefix = s.substring(0, prefix.length()+1);
        }
        return prefix;
    }
}