Day 11: Seating System

Functions:

list_neighbourhood(i, j, height, width)	List all the neighbours of the given seat at position i, j.
apply(layout)	Compute a single iteration.
apply_until_stable(layout)	Run the simulation until the layout does not change anymore.
parse_layout(lines)	Parse the initial layout given as lines.
repr_layout(layout)	Represent the layout as string for debugging.
count_occupied(layout)	Count the number of occupied seats in the layout.

Classes:

Layout(table)

Represent a seat layout.

list_neighbourhood(i: int, j: int, height: int, width: int) → List[Tuple[int, int]]

List all the neighbours of the given seat at position i, j.

The height and width define the limits of the layout.

Requires

• 0 <= j <= width

• 0 <= i <= height

Ensures

• (i, j) not in result

• len(result) <= 8

• all(
      0 <= i <= height and 0 <= j <= width for i, j in result
  )
  

class Layout(table: List[List[str]])

Represent a seat layout.

Methods:

__init__(table)

Initialize with the given values.

Attributes:

table	matrix of the layout
height	height of the layout
width	width of the layout

__init__(table: List[List[str]]) → None

Initialize with the given values.

Requires

• all(
      re.fullmatch(r"[L#.]", cell)
      for row in table
      for cell in row
  )
  

• len(table) > 0
  and len(table[0]) > 0
  and all(
      len(row) == len(table[0])
      for row in table
  )
  

Ensures

• len(self.table) > 0 and self.width == len(self.table[0])

• self.height == len(self.table)

table: Final[List[List[str]]]

matrix of the layout

height: Final[int]

height of the layout

width: Final[int]

width of the layout

apply(layout: Layout) → Tuple[Layout, int]

Compute a single iteration.

Returns

(new layout, number of changes)

Ensures

• all(
      (cell == "." and result_cell == ".")
      or (cell != "." and result_cell in ["L", "#"])
      for row, result_row in zip(layout.table, result[0].table)
      for cell, result_cell in zip(row, result_row)
  )
  

  (Valid change)

• layout.width == result[0].width

• layout.height == result[0].height

apply_until_stable(layout: Layout) → Layout

Run the simulation until the layout does not change anymore.

parse_layout(lines: List[str]) → Layout

Parse the initial layout given as lines.

Requires

• not (len(lines) > 0)
  or all(len(line) == len(lines[0]) for line in lines)
  

  (Lines are a table)

• all(re.match(r"^[.L#]+Z", line) for line in lines)

Ensures

• not len(lines) == 0
  or all(len(line) == len(row) for line, row in zip(lines, result))
  

• len(lines) == result.height

repr_layout(layout: Layout) → str

Represent the layout as string for debugging.

count_occupied(layout: Layout) → int

Count the number of occupied seats in the layout.