longest_palindromic_substring2,cpp

class solution{
    public:

        string LongestPalindromicsubstring(string s){
            int start = 0;
            int maxLen = 0;
            for(int i=1;i<s.length(), i++){
                //even
                    int l = i-1;
                    int r = i;
                        while(l>=0 && r<=s.length() && s[l] == s[r]){
                            if(r-l+1 > maxLen){
                                maxLen = r - l + 1;
                                start = l;
                            }
                            --l;
                            ++r;
                        }
                        //odd
                        l = i-1;
                        r = i+1;
                        while(l>=0 && r<=s.length() && s[l] == s[r]){
                            if( r - l + 1 > maxLen){
                                maxLen = r - l + 1;
                                start = l;
                            }
                            --l;
                            ++r;
                        }
            } return s.substr(start, maxLen);
        }
};