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"
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 class Solution { 2 public: 3 string longestPalindrome(string s) { 4 int leng = 0, size = s.length(); 5 string p; 6 for (int i = 0; i<size; i++) { 7 int l = 1; 8 int S = i, E = i; 9 while (S > 0 && E < size - 1 && s[S - 1] == s[E + 1]) { 10 S--, E++; 11 l += 2; 12 } 13 if (l > leng) { 14 p = s.substr(S, l); 15 leng = l; 16 } 17 } 18 for (int i = 0; i < size-1; i++) { 19 if (i + 1 > size - 1)break; 20 int l = 0; 21 int S = i+1, E = i; 22 while (S > 0 && E < size - 1 && s[S - 1] == s[E + 1]) { 23 S--, E++; 24 l += 2; 25 } 26 if (l > leng) { 27 p = s.substr(S, l); 28 leng = l; 29 } 30 } 31 return p; 32 } 33 };
从大小为1或2的回文串开始扩展