[Leetcode]5. 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 1:

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

Input: "cbbd"
Output: "bb"
题意：求字符串中最长回文子串

class Solution {
public:
    string longestPalindrome(string s) {
        string res;
        for(int i=0;i<s.size();i++)
        {
            for(int j=i,k=i;j>=0&&k<s.size()&&s[j]==s[k];j--,k++)
                if(res.size()<k-j+1)
                    res=s.substr(j,k-j+1);
            for(int j=i,k=i+1;j>=0&&k<s.size()&&s[j]==s[k];j--,k++)
                if(res.size()<k-j+1)
                    res=s.substr(j,k-j+1);
        }
        return res;
    }
};