class Solution {

public:

void compare(string s, int left, int right, int& max_start, int& max_end){

while(left >= 0 && right < s.length() && s[left] == s[right]){

left--;

right++;

}

if(max_end - max_start < right - left - 1){

max_start = left + 1;

max_end = right - 1;

}

}

string longestPalindrome(string s) {

int max_start = 0;

int max_end = 0;

for(int i = 0; i < s.length(); i++){

compare(s, i, i, max_start, max_end);

compare(s, i, i + 1, max_start, max_end);

}

return s.substr(max_start, max_end - max_start + 1);

}

};