advent-of-code/2020/day11_seating.py

171 lines
5.8 KiB
Python

import functools
from collections import Counter
from typing import Dict
def main(filename: str, expected_part_1: int = None, expected_part_2: int = None):
print(f"\n+ Running on {filename}")
with open(filename) as f:
seat_map = f.read()
seat_map_part_1 = SeatMap(seat_map)
seat_map_part_1.evolve_until_stable()
counter_part_1 = seat_map_part_1.total_number_of_occupied()
seat_map_part_2 = SeatMapPart2(seat_map)
seat_map_part_2.evolve_until_stable()
counter_part_2 = seat_map_part_2.total_number_of_occupied()
print(f"1. Found {counter_part_1}")
if expected_part_1:
assert expected_part_1 == counter_part_1
print(f"2. Found {counter_part_2}")
if expected_part_2:
assert expected_part_2 == counter_part_2
Coordinates = tuple[int, int]
class SeatMap:
OCCUPIED = "#"
FREE = "L"
FLOOR = "."
EMPTY_THRESHOLD = 4
def __init__(self, seat_map: str):
self._map = dict() # type: Dict[Coordinates, str]
rows = seat_map.split("\n")
for row_id, row in enumerate(rows):
for col_id, cell in enumerate(row):
self._map[(row_id, col_id)] = cell
self._map_height = len(rows)
self._map_width = len(rows[0])
def __str__(self):
final = []
for row_id in range(0, self._map_height):
row = []
for col_id in range(0, self._map_width):
row.append(self._square_at((row_id, col_id)))
final.append("".join(row))
return "\n".join(final) + "\n"
def _square_at(self, coordinates: Coordinates) -> str:
return self._map[coordinates]
def total_number_of_occupied(self) -> int:
counter = Counter("".join(self._map.values()))
return counter[self.OCCUPIED]
def evolve_until_stable(self):
old_map = self._map
next_stage_map = self._evolve()
while next_stage_map != old_map:
old_map = next_stage_map
next_stage_map = self._evolve()
def _evolve(self):
next_stage_map = dict()
for coord, square in self._map.items():
next_stage_map[coord] = self._square_evolve(square, coord)
self._map = next_stage_map
return self._map
def _square_evolve(self, square: str, coordinates: Coordinates) -> str:
if square == self.FLOOR:
return square
occupied_adjacent = self._number_of_occupied_adjacent(coordinates)
if square == self.FREE and occupied_adjacent == 0:
return self.OCCUPIED
if square == self.OCCUPIED and occupied_adjacent >= self.EMPTY_THRESHOLD:
return self.FREE
return square
def _number_of_occupied_adjacent(self, coordinates: Coordinates) -> int:
count_occupied = 0
for seat in self._visible_seats(coordinates):
if seat == self.OCCUPIED:
count_occupied += 1
return count_occupied
def _visible_seats(self, coordinates: Coordinates) -> list[str]:
adjacent_cells = [
self._find_top_left(coordinates),
self._find_top(coordinates),
self._find_top_right(coordinates),
self._find_right(coordinates),
self._find_bottom_right(coordinates),
self._find_bottom(coordinates),
self._find_bottom_left(coordinates),
self._find_left(coordinates),
]
return list(map(self._square_at, filter(None, adjacent_cells)))
@functools.lru_cache(None)
def _find_top_left(self, coordinates: Coordinates) -> Coordinates | None:
return self._find_with_delta(coordinates, (-1, -1))
@functools.lru_cache(None)
def _find_with_delta(
self, coordinates: Coordinates, delta: tuple[int, int]
) -> Coordinates | None:
other_coord = (coordinates[0] + delta[0], coordinates[1] + delta[1])
try:
self._square_at(other_coord)
except KeyError:
return None
return other_coord
@functools.lru_cache(None)
def _find_top(self, coordinates: Coordinates) -> Coordinates | None:
return self._find_with_delta(coordinates, (-1, 0))
@functools.lru_cache(None)
def _find_top_right(self, coordinates: Coordinates) -> Coordinates | None:
return self._find_with_delta(coordinates, (-1, 1))
@functools.lru_cache(None)
def _find_right(self, coordinates: Coordinates) -> Coordinates | None:
return self._find_with_delta(coordinates, (0, 1))
@functools.lru_cache(None)
def _find_bottom_right(self, coordinates: Coordinates) -> Coordinates | None:
return self._find_with_delta(coordinates, (1, 1))
@functools.lru_cache(None)
def _find_bottom(self, coordinates: Coordinates) -> Coordinates | None:
return self._find_with_delta(coordinates, (1, 0))
@functools.lru_cache(None)
def _find_bottom_left(self, coordinates: Coordinates) -> Coordinates | None:
return self._find_with_delta(coordinates, (1, -1))
@functools.lru_cache(None)
def _find_left(self, coordinates: Coordinates) -> Coordinates | None:
return self._find_with_delta(coordinates, (0, -1))
class SeatMapPart2(SeatMap):
EMPTY_THRESHOLD = 5
@functools.lru_cache(None)
def _find_with_delta(
self, coordinates: Coordinates, delta: tuple[int, int]
) -> Coordinates | None:
other_coord = (coordinates[0] + delta[0], coordinates[1] + delta[1])
try:
other_square = self._square_at(other_coord)
while other_square == self.FLOOR:
other_coord = (other_coord[0] + delta[0], other_coord[1] + delta[1])
other_square = self._square_at(other_coord)
except KeyError:
return None
return other_coord
if __name__ == "__main__":
main("inputs/day11-test1", 37, 26)
main("inputs/day11", 2324, 2068)