[Python]Leetcode 5. Longest Palindromic Substring

题目描述

Given a string s, find the longest palindromic substring in s. You may assume that the maximum length of s is 1000.

Example 1:

Input: “babad”
Output: “bab”
Note: “aba” is also a valid answer.
Example 2:

Input: “cbbd”
Output: “bb”

代码解析

class Solution(object):
    def longestPalindrome(self, s):
        """
        :type s: str
        :rtype: str
        """
        ret=''
        for i in xrange(len(s)):
            str_hw=self.huiwen(s,i,i)
            if len(str_hw)>len(ret):
                ret=str_hw
            str_hw=self.huiwen(s,i,i+1)
            if len(str_hw)>len(ret):
                ret=str_hw
        return ret
    
    def huiwen(self, s ,i ,j ):
        while i>=0 and j<=len(s)-1 and s[i]==s[j]:
            i-=1
            j+=1
            
        return s[i+1:j]