中心扩散法| #密码截取#

import java.util.Scanner;
import java.io.*;

// 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 scanner = new Scanner(System.in);
        scanner.useDelimiter("\n");
        while (scanner.hasNext()){
            String S = scanner.next();
            int max = 0;
            for (int i = 0; i < S.length(); i++) {
                int ABA = add(S, i, i);
                int ABBA = add(S, i, i+1);
                max = Math.max(ABA, Math.max(ABBA, max));
            }
            System.out.println(max);
        }


    }

    public static int add(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;
    }
}