HJ85 longest palindrome substring

Given a string containing only lowercase letters, find the length of its longest palindrome substring.

The so-called palindrome refers to a left-right symmetrical string.

The so-called substring refers to a string that deletes part of its prefix and suffix (or not)

Data range: string length 1\le s\le 350\1≤s≤350

Advanced:Time complexity: O(n)\O(n) , Space complexity: O(n)\O(n)

The palindrome is

a = a[::-1]