题解 | #密码截取#

import java.util.*;

public class Main {
    public static void main(String [] args) {
        Scanner sc = new Scanner(System.in);
        char[] str = sc.nextLine().toCharArray();
        boolean f = false;
        System.out.println(calc(str, str.length, f));

    }

    public static int calc(char[] arr, int length, boolean f) {
        if (length < 2) {
            return length;
        }
        int i = 0;
        int index = length - 1;
        while (i + index < arr.length) {
            int end = i + index;
            boolean find = true;
            for (int j = i; j < end; j++,end--) {
                if (arr[j] != arr[end]) {
                    find = false;
                    break;
                }
            }
            if (find) {
                f = true;
                break;
            }
            i++;
        }
        if (f) {
            return length;
        }
        return calc(arr, length - 1, f);
    }
}