题解 | #密码截取#

import java.util.Scanner;

// 服咯，竟然做了40分钟，中等题做的好慢啊
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        
        String p = in.nextLine();
        char[] chars = p.toCharArray();
        int max = 0;
        for(int i=0;i<chars.length - 2;i++) {
            if (chars[i] == chars[i+1]) {
                int len = i + 1 > chars.length - i - 1 ? chars.length - i - 1 : i + 1;
                int temp = 0;
                for(int j=0;j < len; j++) {
                    if(chars[i - j] == chars[i+1+j]) {
                        temp++;
                    } else {
                        break;
                    }
                }
                max = max < 2 * temp ? 2 * temp : max;
            }
            if (chars[i] == chars[i+2]) {
                int len = i + 1 > chars.length - i - 2 ? chars.length - i - 2 : i + 1;
                int temp = 0;
                for(int j=0;j < len; j++) {
                    if(chars[i - j] == chars[i+2+j]) {
                        temp++;
                    } else {
                        break;
                    }
                }
                max = max < 2 * temp + 1 ? 2 * temp + 1 : max;
            }
        }
        System.out.println(max);
    }
}