5. Longest Palindromic Substring 最长的回文子串

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"

 

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class Solution1:     def longestPalindrome(self, s):         """         :type s: str         :rtype: str         """         res = ""         for i in range(len(s)):             j = i + len(res) + 1             while j <= len(s):                 cur = s[i:j]                 if len(cur) > len(res) and cur == cur[::-1]:                     res = cur                 j += 1         return res     class Solution2:     def longestPalindrome(self, s):         if len(s) == 0:             return ""         maxLen = 1         start = 0         for i in range(len(s)):             cur = s[i - maxLen - 1:i + 1]             if i - maxLen >= 1 and cur == cur[::-1]:                 start = i - maxLen - 1                 maxLen += 2                 continue               cur = s[i - maxLen:i + 1]             if i - maxLen >= 0 and cur == cur[::-1]:                 start = i - maxLen                 maxLen += 1           return s[start:start + maxLen]     s = "babad" #s = "cbbd" solution = Solution2() res = solution.longestPalindrome(s) # print(res)

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