string longestPalindrome(string s){

if (s.size() < 2) return s;

int n = s.size(), maxLen = 0, start = 0;

for (int i = 0; i < n - 1; ++i)

{

searchPalindrome(s, i, i, start, maxLen);

searchPalindrome(s, i, i+1, start, maxLen);

}

return s.substr(start, maxLen);

}

void searchPalindrome(string s, int left, int right, int& start, int& maxLen){

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

--left; ++right;

}

if (maxLen < right - left - 1) {

start = left + 1;

maxLen = right - left - 1;

}

}

{

}