求最长回文子串 第一种解法：动态规划（内存分配较多，且时间复杂度为O(n^2)）第2种解法:Manacher算法-Find the longest palindrome substring First Solution: Dynamic Programming (memory allocation more, and the time complexity is O (n ^ 2)) The second solution: Manacher algorithm

求一个字符串的最长回文子串的长度。比如字符串 abaaba 的最长回文子串的长度就是6.-Seeking a string longest palindromic substring length. For example, the string " abaaba" longest palindromic substring length is 6.