Longest Palindromic Substring

class Solution {
public:
    string longestPalindrome(string s) {
        int len=s.size();
        int left,right;
        int begin=0,maxlen=0;
        if(len<=1)
            return s;
        else
        {
        for(int i=1;i<len;i++)
        {
            left=i-1;
            right=i;
            while(left>=0&&right<len&&s[left]==s[right])
            {
                left--;
                right++;
            }
            if(right-left-1>maxlen)
            {
                begin=left+1;
                maxlen=right-left-1;
            }
            left=i-1;
            right=i+1;
            while(left>=0&&right<len&&s[left]==s[right])
            {
                left--;
                right++;
            }
            if(right-left-1>maxlen)
            {
                begin=left+1;
                maxlen=right-left-1;
            }
        }
        }
        return s.substr(begin,maxlen);
        }
};