string[] examples =
{
    "mjqjpqmgbljsphdztnvjfqwrcgsmlb",
    "bvwbjplbgvbhsrlpgdmjqwftvncz",
    "nppdvjthqldpwncqszvftbrmjlhg",
    "nznrnfrfntjfmvfwmzdfjlvtqnbhcprsg",
    "zcfzfwzzqfrljwzlrfnpqdbhtmscgvjw",
};

int[] uniqueCount = { 4, 14 };

/**** Part 01 ***/
foreach (var unique in uniqueCount)
{
    Console.WriteLine(String.Format("\nFinding based on {0} unique consequetive characters", unique));

    // Perform ops on examples
    foreach (string example in examples)
    {
        PrintFirstUniqueIndex(example, unique);
    }

    // Do it on the real puzzle
    string fileName = "puzzle-input.txt";
    using (StreamReader reader = File.OpenText(fileName))
    {
        string? line = reader.ReadLine();
        if (line != null)
        {
            PrintFirstUniqueIndex(line, unique);
        }
        else
        {
            throw new InvalidDataException();
        }
    }
}

void PrintFirstUniqueIndex(string str, int uniqueLength)
{
    for (int i = 0; i < str.Length; i++)
    {
        var substr = str.Substring(i, uniqueLength);
        if (substr.Distinct().Count() == uniqueLength)
        {
            Console.WriteLine("Unique Index Start: " + (i+uniqueLength));
            return;
        }
    }

    throw new InvalidDataException();
}