Longest palindromic substring

Problem: Given a string S, find the longest palindromic substring in S.

Solution:

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string expandAroundCenter(string s, int c1, int c2) {   int l = c1, r = c2;   int n = s.length();   while (l &gt;= 0 &amp;&amp; r &lt;= n-1 &amp;&amp; s[l] == s[r]) {     l--;     r++;   }   return s.substr(l+1, r-l-1); }    string longestPalindromeSimple(string s) {   int n = s.length();   if (n == 0) return &quot;&quot;;   string longest = s.substr(0, 1); // a single char itself is a palindrome   for (int i = 0; i < longest.length(); i++) {          String p1 = expandAroundCenter(s, i, i)     if(p1.length() > longest.length())       longest = p1;       string p2 = expandAroundCenter(s, i, i+1);     if (p2.length() &gt; longest.length())       longest = p2;   }   return longest; }