public Day20() { Part = 2; Key = InputLine.ToBitArray('#'); Game = new GameOfLife(true); Game.Expanding = true; Game.NeighborFunction = pos => pos.RectAround(1, 1); Game.UpdateFunction = cell => { var index = cell.Neighbors().BitsToInt(); return(Key[index]); }; var input = AllGroups[1].Select2D(c => c == '#').ToGrid(); foreach (var(pos, value) in input) { Game[pos] = value; } }