There you can find Python and Java implementations of the algorithm (C++ implementation contains errors). And here is C# implementation that is just a translation of those algorithms. public static int LongestPalindrome (string seq) { int Longest = 0; List<int> l = new List<int> (); int i = 0; int palLen = 0; int s = 0; int e = 0; while (i<seq.