题解 | #查找两个字符串a,b中的最长公共子串#

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        // while (in.hasNextInt()) { // 注意 while 处理多个 case
        //     int a = in.nextInt();
        //     int b = in.nextInt();
        //     System.out.println(a + b);
        // }
        String s1 = in.next();
        String s2 = in.next();
        if (s1.length() > s2.length()) {
            System.out.print(sameSubStr(s1, s2));
        } else {
            System.out.print(sameSubStr(s2, s1));
        }
    }

    private static String sameSubStr(String longStr, String shortStr) {
        int len = shortStr.length();
        for (int i = len; i > 0; i--) {
            for (int j = 0; j < len - i + 1; j++) {
                String sub = shortStr.substring(j, i + j);
                if (longStr.contains(sub)) {
                    return sub;
                }
            }
        }
        return null;
    }
}