advent-of-code/2020/Python/day24.py
2020-12-24 17:02:22 +01:00

153 lines
4.2 KiB
Python

from enum import Enum
from typing import Tuple
class Direction(Enum):
E = 0
SE = 1
SW = 2
W = 3
NW = 4
NE = 5
def convert_string(path: str) -> list[Direction]:
out, i = [], 0
while i < len(path):
char = path[i]
if char in ['s', 'n']:
i += 1
char += path[i]
if char == "e":
out.append(Direction.E)
elif char == "w":
out.append(Direction.W)
elif char == "ne":
out.append(Direction.NE)
elif char == "nw":
out.append(Direction.NW)
elif char == "se":
out.append(Direction.SE)
elif char == "sw":
out.append(Direction.SW)
i += 1
return out
def determine_neighbour(row: int, col: int, direction: Direction) -> Tuple[int, int]:
if direction == Direction.E:
return row, col+1
elif direction == Direction.SE:
return (row+1, col+1) if row % 2 == 0 else (row+1, col)
elif direction == Direction.SW:
return (row+1, col) if row % 2 == 0 else (row+1, col-1)
elif direction == Direction.W:
return row, col-1
elif direction == Direction.NW:
return (row-1, col) if row % 2 == 0 else (row-1, col-1)
elif direction == Direction.NE:
return (row-1, col+1) if row % 2 == 0 else (row-1, col)
def find_tile(start_r: int, start_c: int, path: str) -> Tuple[int, int]:
path = convert_string(path)
tile_r, tile_c = start_r, start_c
for direction in path:
tile_r, tile_c = determine_neighbour(tile_r, tile_c, direction)
return tile_r, tile_c
def parse_data() -> list[str]:
out = []
with open("input.txt") as file:
for line in file:
out.append(line.rstrip())
return out
def solve_p1(data: list[str]) -> int:
black_tiles: set[Tuple[int, int]] = set()
for line in data:
found_tile = find_tile(0, 0, line)
if found_tile in black_tiles:
black_tiles.remove(found_tile)
else:
black_tiles.add(found_tile)
return len(black_tiles)
DATA = parse_data()
print(solve_p1(DATA))
# Part 2 is kind of done ad hoc today because christmas :p
# not much time to work on it
class Grid:
def __init__(self, row: int, col: int):
self.row = row
self.col = col
self.grid = []
for i in range(row):
row_list = []
for j in range(col):
row_list.append(False)
self.grid.append(row_list)
def flip(self, row: int, col: int, state: bool) -> None:
self.grid[row][col] = state
def get_state(self, row: int, col: int) -> bool:
if 0 <= row < len(self.grid) and 0 <= col < len(self.grid[0]):
return self.grid[row][col]
return False
def count_ns(self, row: int, col: int) -> int:
if row % 2 == 0:
ns = [(0, 1), (0, -1), (1, 1), (1, 0), (-1, 1), (-1, 0)]
else:
ns = [(0, 1), (0, -1), (1, 0), (1, -1), (-1, 0), (-1, -1)]
counted = 0
for ns_r, ns_c in ns:
counted += self.get_state(row+ns_r, col+ns_c)
return counted
def next(self) -> 'Grid':
next_grid = Grid(self.row, self.col)
for i in range(self.row):
for j in range(self.col):
active_ns = self.count_ns(i, j)
active = self.get_state(i, j)
if active and (active_ns == 0 or active_ns > 2):
next_grid.flip(i, j, state=False)
elif not active and active_ns == 2:
next_grid.flip(i, j, state=True)
else:
next_grid.flip(i, j, state=active)
return next_grid
def count_black(self):
counted = 0
for i in range(self.row):
for j in range(self.col):
counted += self.get_state(i, j)
return counted
grid = Grid(row=200, col=200)
black_tiles: set[Tuple[int, int]] = set()
for line in DATA:
found_tile = find_tile(0, 0, line)
if found_tile in black_tiles:
black_tiles.remove(found_tile)
else:
black_tiles.add(found_tile)
for (x, y) in black_tiles:
grid.flip(x+100, y+100, True)
for i in range(100):
grid = grid.next()
print(grid.count_black())