(python)leetcode刷题笔记05 Longest Palindromic Substring

5. Longest Palindromic Substring

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

Example:

Input: "babad"

Output: "bab"

Note: "aba" is also a valid answer.

Example:

Input: "cbbd"

Output: "bb"

 1 class Solution:
 2     def solve(self,s,l,r):
 3         while r<len(s) and l>=0 and s[l]==s[r]:
 4             l-=1
 5             r+=1
 6         return s[l+1:r]
 7     def longestPalindrome(self,s):
 8         if len(s) == 0:
 9             return 0
10         max_string=''
11         for i in range(len(s)):
12             #奇数长度回文串如ababa
13             tmp=self.solve(s,i,i)
14             if len(tmp)>len(max_string):
15                 max_string=tmp
16             #偶数回文串如abba
17 
18             tmp=self.solve(s,i,i+1)
19             if len(tmp)>len(max_string):
20                 max_string=tmp
21 
22         return max_string

Code

 1 def solve(s,l,r):
 2     while r<len(s) and l>=0 and s[l]==s[r]:
 3         l-=1
 4         r+=1
 5     return s[l+1:r]
 6 def longestPalindrome(s):
 7     if len(s) == 0:
 8         return 0
 9     max_string=''
10     for i in range(len(s)):
11         #奇数长度回文串如ababa
12         tmp=solve(s,i,i)
13         if len(tmp)>len(max_string):
14             max_string=tmp
15         #偶数回文串如abba
16 
17         tmp=solve(s,i,i+1)
18         if len(tmp)>len(max_string):
19             max_string=tmp
20 
21     return max_string
22 
23 
24 
25 
26 print(longestPalindrome('ababa'))

Debug Code