题解 | #密码截取#

import java.util.Scanner;

public class Main{ public static void main(String[] args){ Scanner sc = new Scanner(System.in); while(sc.hasNext()){ String str = sc.nextLine(); // 输出结果 System.out.println(solution(str)); } }

private static int solution(String str){
    // 定义一个对象用于存储回文字符串的长度
    int len = 0;
    int maxLen = 0;
    // 将字符串转换为字符数组
    char[] chars = str.toCharArray();
    for(int i = 0; i < chars.length; i++){
        // aba型回文
       len = longest(chars,i - 1,i + 1,1);
        if(len != 1 && len > maxLen) maxLen = len;
        // abba型回文
        len = longest(chars,i,i + 1,0);
       if(len > maxLen) maxLen = len;
    }
   return maxLen;
}

private static int longest(char[] c,int m, int n,int l){
    if( m >= 0 && n < c.length && c[m] == c[n]){
        l += 2;
        return longest(c,m - 1, n + 1, l);
    } else{
        return l;
    }
}

}