public static void Main()
Console.WriteLine(EncodeShortLink(1679616));
Console.WriteLine(EncodeShortLink(59796171));
public static readonly string Alphabet = "abcdefghijklmnopqrstuvwxyz0123456789";
public static readonly long Base = Alphabet.Length;
public static string EncodeShortLink(long index)
if (index == 0) return Alphabet[0].ToString();
var s = new StringBuilder();
s.Append(Alphabet[Convert.ToInt32(index % Base)]);
return string.Join(string.Empty, s.ToString().Reverse());