题解 | #最长回文子串#

import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param A string字符串 
     * @return int整型
     */
    public int getLongestPalindrome (String A) {
        // write code here
        if (A == null || A.length() < 1) {
            return 0;
        }
        char[] arr = A.toCharArray();
        int n = arr.length;
        int res = 0;
        for (int i = 0; i < n; i++) {
            int len1 = helper(arr, i, i);
            int len2 = helper(arr, i, i + 1);
            res = Math.max(res, Math.max(len1, len2));
        }
        return res;
    }

    private int helper(char[] arr, int l, int r) {
        while (l >= 0 && r < arr.length) {
            if (arr[l] == arr[r]) {
                l--;
                r++;
            } else {
                break;
            }
        }
        return r - l - 1;
    }
}