public string LongestPalindrome(string s)
{
IndexRange current = new IndexRange(0, 0);
char[] charArray = s.ToCharArray();
for (int i = 0; i < charArray.Length; i++)
{
IndexRange range1 = Expand(charArray, i, i);
if (range1 != null && range1.Length > current.Length)
{
current = range1;
}
IndexRange range2 = Expand(charArray, i, i + 1);
if (range2 != null && range2.Length > current.Length)
{
current = range2;
}
}
return(current.GetSubString(s));
}
