internal static void Part2()
{
var input = Input.Lines(5);
// Build set of all possible seat numbers
var allSeats = Enumerable.Range(1, 126)
.SelectMany(row => Enumerable.Range(0, 8).Select(col => Day5Calculator.CalcSeatId(row, col)))
.ToHashSet();
// Scanned seats
var foundSeats = input.Select(Day5Calculator.CalcSeatId).ToHashSet();
var remaining = allSeats.Except(foundSeats);
// Find seat that has an ID +1 and -1 of it in the list of scanned seats
var mine = remaining
.First(id => foundSeats.Contains(id - 1) && foundSeats.Contains(id + 1));
Console.WriteLine(mine);
}
public void TestCalcSeat()
{
Assert.Equal((70, 7), Day5Calculator.CalcSeat("BFFFBBFRRR"));
Assert.Equal((14, 7), Day5Calculator.CalcSeat("FFFBBBFRRR"));
Assert.Equal((102, 4), Day5Calculator.CalcSeat("BBFFBBFRLL"));
}
