advent-of-code/2024/d13/ex2/ex2.py

70 lines
1.7 KiB
Python
Executable file

#!/usr/bin/env python
import dataclasses
import sys
from typing import NamedTuple
class Point(NamedTuple):
x: int
y: int
@dataclasses.dataclass
class ClawMachine:
a_delta: Point
b_delta: Point
prize: Point
def solve(input: str) -> int:
def parse_button(input: str) -> Point:
deltas = input.split(": ")[1].strip()
x, y = map(lambda delta: int(delta.split("+")[1]), deltas.split(", "))
return Point(x, y)
def parse_prize(input: str) -> Point:
coords = input.split(": ")[1].strip()
x, y = map(lambda delta: int(delta.split("=")[1]), coords.split(", "))
return Point(10000000000000 + x, 10000000000000 + y)
def parse_claw_machine(input: list[str]) -> ClawMachine:
assert len(input) == 3 # Sanity check
return ClawMachine(
parse_button(input[0]),
parse_button(input[1]),
parse_prize(input[2]),
)
def parse(input: str) -> list[ClawMachine]:
return [parse_claw_machine(group.splitlines()) for group in input.split("\n\n")]
def play_machine(machine: ClawMachine) -> int | None:
a_dx, a_dy = machine.a_delta
b_dx, b_dy = machine.b_delta
px, py = machine.prize
a = (px * b_dy - py * b_dx) // (b_dy * a_dx - b_dx * a_dy)
b = (px * a_dy - py * a_dx) // (a_dy * b_dx - a_dx * b_dy)
if a * a_dx + b * b_dx != px:
return None
if a * a_dy + b * b_dy != py:
return None
return 3 * a + b
claw_machines = parse(input)
return sum(
tokens for tokens in map(play_machine, claw_machines) if tokens is not None
)
def main() -> None:
input = sys.stdin.read()
print(solve(input))
if __name__ == "__main__":
main()