Day 24: Lobby Layout

Classes:

Cell(x, y, z)	Represent a hexagonal cell of the layout using cube coordinates.
Direction(value)	Enumerate the possible directions from a hexagonal cell.

Functions:

cell_as_tuple(cell)	Convert the cell into a tuple of x, y and z coordinates.
next_cell(cell, direction)	Retrieve the next cell starting from cell in the direction.
follow_directions(start, directions)	Walk the directions from the start.
parse_line(line)	Parse the input line.
stringify_directions(directions)	Represent the directions as a concatenated text.
count_flips(plan)	Count how many cells had to flip for the given plan.

Data:

VALUE_TO_DIRECTION	Map string literal of Direction 🠒 Direction.
DIRECTIONS_RE	Express a list of directions
ONE_DIRECTION_RE	Express a single direction

class Cell(x: int, y: int, z: int)

Represent a hexagonal cell of the layout using cube coordinates.

See https://www.redblobgames.com/grids/hexagons/.

Methods:

__init__(x, y, z)

Initialize with the given values.

Attributes:

x	X-coordinate (south-east, north-west)
y	Y-coordinate (south-west, north-east)
z	Z-coordinate (east, west)

__init__(x: int, y: int, z: int) → None

Initialize with the given values.

Requires

• x + y + z == 0

x: Final[int]

X-coordinate (south-east, north-west)

y: Final[int]

Y-coordinate (south-west, north-east)

z: Final[int]

Z-coordinate (east, west)

cell_as_tuple(cell: Cell) → Tuple[int, int, int]

Convert the cell into a tuple of x, y and z coordinates.

class Direction(value)

Enumerate the possible directions from a hexagonal cell.

Attributes:

EAST
SOUTH_EAST
SOUTH_WEST
WEST
NORTH_WEST
NORTH_EAST

EAST = 'e'

SOUTH_EAST = 'se'

SOUTH_WEST = 'sw'

WEST = 'w'

NORTH_WEST = 'nw'

NORTH_EAST = 'ne'

VALUE_TO_DIRECTION = {'e': Direction.EAST, 'ne': Direction.NORTH_EAST, 'nw': Direction.NORTH_WEST, 'se': Direction.SOUTH_EAST, 'sw': Direction.SOUTH_WEST, 'w': Direction.WEST}

Map string literal of Direction 🠒 Direction.

next_cell(cell: Cell, direction: Direction) → Cell

Retrieve the next cell starting from cell in the direction.

follow_directions(start: Cell, directions: List[Direction]) → Cell

Walk the directions from the start.

Returns

The final Cell of the journey

DIRECTIONS_RE = re.compile('^(se|sw|nw|ne|w|e)+\\Z')

Express a list of directions

ONE_DIRECTION_RE = re.compile('(se|sw|nw|ne|w|e)')

Express a single direction

parse_line(line: str) → List[Direction]

Parse the input line.

Requires

• len(line) > 0 ⇒ DIRECTIONS_RE.match(line)

Ensures

• stringify_directions(result) == line

• len(line) == 0 ⇒ len(result) == 0

stringify_directions(directions: List[Direction]) → str

Represent the directions as a concatenated text.

Ensures

• parse_line(result) == directions

count_flips(plan: List[List[Direction]]) → int

Count how many cells had to flip for the given plan.

The plan consists of different journeys, all starting from the cell zero.