ShortUrl

ShortUrl.cs

// 2147483647 -> 8fs-Kx
public static class ShortUrl
{
	// removed ambiguous characters ('I', 'l', '1', 'O' and '0')
	// removed vowels (to prevent offensive words)
	public static readonly string Alphabet = "23456789bcdfghjkmnpqrstvwxyzBCDFGHJKLMNPQRSTVWXYZ-_";
	public static readonly int Base = Alphabet.Length;

	public static string Encode(int toEncode)
	{
		var builder = new StringBuilder();

		while (toEncode > 0)
		{
			builder.Insert(0, Alphabet[toEncode % Base]);
            toEncode = toEncode / Base;
		}

		return builder.ToString();
	}

	public static int Decode(string toDecode)
	{
		int decodedValue = 0;
		
		for (int index = 0; index < toDecode.Length; index++)
		{
			decodedValue = decodedValue * Base + Alphabet.IndexOf(toDecode[index]);
		}
		
		return decodedValue;
	}
}