题解 | #回文数索引#

import java.util.Scanner;
 
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int num = sc.nextInt();

        while (num-- > 0) {
            StringBuilder sb = new StringBuilder(sc.next());
            System.out.println(isPlalindrome(sb));
        }
    }
    public static int isPlalindrome(StringBuilder sb) {
        // 初始下标
        int left = 0;
        // 末尾下标
        int right = sb.length() - 1;
        while(left < right) {
            // 判断左右两边下标值是否相等
            if(sb.charAt(left) != sb.charAt(right)) {
                // 如果删除左边的下标值, 判断左边的下一个下标值与右边值是否相等 
                // 如果相等证明要删除的是左边下标值，否则是右边下标值
                if(sb.charAt(left + 1) == sb.charAt(right)) {
                    return left;
                } else {
                    return right;
                }
            }
            left++;
            right--;
        }
        // 循环到这时，证明该字符串是回文
        return -1;
    }
}