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() == 0) {
            return 0;
        }
        if (A.length() == 1) {
            return 1;
        }
        int res = 1;
        for (int i = 0; i < A.length(); i++) {
            res = Math.max(res, Math.max(helper(A, i, i), helper(A, i, i + 1)));
        }
        return res;
    }

    public int helper(String str, int left, int right) {
        boolean flag = left == right ? true : false;
        int counter = 0;
        while (left <= right && left >= 0 && right <= str.length() - 1 &&
                str.charAt(left) == str.charAt(right)) {
            counter++;
            left--;
            right++;
        }
        return flag != true ? counter * 2 : counter * 2 - 1;
    }

}

使用 counter 计数来求字符数比较好理解一些