题解 | #密码截取#

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);
        String strInput = in.nextLine();
        int max = 0;
        for(int i=1;i<strInput.length();i++){
            //ABA
            int aba = loop(strInput,i-1,i+1);
            // ABBA
            int abba = loop(strInput,i,i+1);
            max = Math.max(max,Math.max(aba,abba));
        }
        System.out.println(max);
    }
    //双指针遍历
    private static int loop(String s,int left,int right){
        while(left>=0&&right<=s.length()-1&&s.charAt(left)==s.charAt(right)){
            left--;
            right++;
        }
        return right-left-1;
    }
}