static async Task Main(string[] args)
{
// highest seat ID in the source data
// convert "FBFBFB" notation to binary
var seats = await AsyncFileReader.ReadLines("data.txt")
.Select(Seat.FromString)
.ToListAsync();
var maxSeatID = seats.Max(s => s.SeatID);
Console.WriteLine("Max seatID is {0}", maxSeatID);
// find the unoccupied seats
var allSeats = Enumerable.Range(0, maxSeatID)
.ToDictionary(n => n, n => seats.SingleOrDefault(s => s.SeatID == n));
Console.WriteLine("Missing seats:");
foreach (var index in allSeats.Where(kvp => kvp.Value == null))
{
Console.WriteLine(index.Key);
}
}