advent-of-code/2022/d17/ex1/ex1.py

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2022-12-17 12:52:24 +01:00
#!/usr/bin/env python
import enum
import itertools
import sys
from collections.abc import Iterator
from typing import NamedTuple
class Point(NamedTuple):
x: int
y: int
def __add__(self, other):
if not isinstance(other, Point):
return NotImplemented
return Point(self.x + other.x, self.y + other.y)
def __sub__(self, other):
if not isinstance(other, Point):
return NotImplemented
return Point(self.x - other.x, self.y - other.y)
def translate(points: set[Point], delta: Point) -> set[Point]:
return {p + delta for p in points}
class Rock(str, enum.Enum):
LINE = "####"
PLUS = ".#.\n###\n.#."
CORNER = "..#\n..#\n###"
VERTICAL_LINE = "#\n#\n#\n#"
SQUARE = "##\n##"
@classmethod
def stream(cls) -> Iterator["Rock"]:
yield from itertools.cycle(iter(cls))
def to_points(self) -> set[Point]:
res: set[Point] = set()
for y, line in enumerate(reversed(self.splitlines())):
for x, c in enumerate(line):
if c == ".":
continue
res.add(Point(x, y))
return res
class JetStream(str, enum.Enum):
LEFT = "<"
RIGHT = ">"
@classmethod
def stream(cls, jet_pattern: str) -> Iterator["JetStream"]:
yield from itertools.cycle(map(cls, jet_pattern))
def as_delta(self) -> Point:
if self == self.LEFT:
return Point(-1, 0)
if self == self.RIGHT:
return Point(1, 0)
assert False # Sanity check
def solve(input: list[str]) -> int:
assert len(input) == 1 # Sanity check
rocks = Rock.stream()
jet_stream = JetStream.stream(input[0])
fallen_stack: set[Point] = set()
max_height = 0
LEFT_WALL = -1
RIGHT_WALL = 7
FLOOR = 0
def step(rock: set[Point]) -> tuple[set[Point], bool]:
jet = next(jet_stream)
# Check if it can be pushed by the jet, or if it hits an obstacle
pushed_rock = translate(rock, jet.as_delta())
if not (fallen_stack & pushed_rock) and all(
LEFT_WALL < p.x < RIGHT_WALL for p in pushed_rock
):
rock = pushed_rock
# Check if it can go down
fallen_rock = translate(rock, Point(0, -1))
if not (fallen_stack & fallen_rock) and all(p.y > FLOOR for p in fallen_rock):
return fallen_rock, True
return rock, False
def simulate_rock_fall() -> None:
nonlocal max_height
rock = next(rocks).to_points()
# Align 2 units away from LEFT_WALL and 3 higher than
# current stack
rock = translate(rock, Point(2, max_height + 3 + 1))
while True:
rock, keep_going = step(rock)
if not keep_going:
break
fallen_stack.update(rock)
max_height = max(max_height, max(p.y for p in rock))
for _ in range(2022):
simulate_rock_fall()
return max_height
def main() -> None:
input = sys.stdin.read().splitlines()
print(solve(input))
if __name__ == "__main__":
main()