advent_of_code_2021

day22_part1.py (3571B)

---

 #!/usr/bin/env python
 """Advent of Code 2021, day 22 (part 1): Reactor Reboot
 Apply on/off instructions to a 3D grid of cuboids"""
 
 # Ugh, the way this problem is written you just KNOW that Part 2 is going to
 # require an entirely different approach, but yesterday really burned me on
 # overthinking situations that didn't come up, so I'm going to be chill today.
 
 from typing import Tuple, List, NewType
 import re
 from functools import reduce
 
 # For part 1 we'll just represent everything in the -50..50 bounds explicitly.
 # I suspect part 2 will require a different approach!
 import numpy as np
 
 from utils import get_puzzle_input
 
 EXAMPLE_INPUT = \
 """on x=-20..26,y=-36..17,z=-47..7
 on x=-20..33,y=-21..23,z=-26..28
 on x=-22..28,y=-29..23,z=-38..16
 on x=-46..7,y=-6..46,z=-50..-1
 on x=-49..1,y=-3..46,z=-24..28
 on x=2..47,y=-22..22,z=-23..27
 on x=-27..23,y=-28..26,z=-21..29
 on x=-39..5,y=-6..47,z=-3..44
 on x=-30..21,y=-8..43,z=-13..34
 on x=-22..26,y=-27..20,z=-29..19
 off x=-48..-32,y=26..41,z=-47..-37
 on x=-12..35,y=6..50,z=-50..-2
 off x=-48..-32,y=-32..-16,z=-15..-5
 on x=-18..26,y=-33..15,z=-7..46
 off x=-40..-22,y=-38..-28,z=23..41
 on x=-16..35,y=-41..10,z=-47..6
 off x=-32..-23,y=11..30,z=-14..3
 on x=-49..-5,y=-3..45,z=-29..18
 off x=18..30,y=-20..-8,z=-3..13
 on x=-41..9,y=-7..43,z=-33..15
 on x=-54112..-39298,y=-85059..-49293,z=-27449..7877
 on x=967..23432,y=45373..81175,z=27513..53682
 """
 
 Instruction = NewType(
     'Instruction',
     Tuple[bool, Tuple[int, int], Tuple[int, int], Tuple[int, int]]
 )
 
 def parse_input(input_string: str) -> List[Instruction]:
     """Given the puzzle input, return a list of "on" (True) or "off" (False)
     instructions and their x, y, and z bounds"""
     range_pattern = r"(-?\d+)\.\.(-?\d+)"
     groups = [
         match.groups()
         for l in input_string.rstrip('\n').split('\n')
         if (match := re.match("^(on|off) x=" + range_pattern
                               + ",y=" + range_pattern
                               + ",z=" + range_pattern, l)) is not None
     ]
     return [Instruction((
         {'on': True, 'off': False}[x[0]],
         (int(x[1]), int(x[2])),
         (int(x[3]), int(x[4])),
         (int(x[5]), int(x[6]))
     )) for x in groups]
 
 def inside_initialization_area(instruction: Instruction) -> bool:
     """Returns True iff the instruction is fully inside the area -50..50 along
     all thre axes"""
     return all(-50 <= i <= 50 for p in instruction[1:4] for i in p)
 
 def apply_step(reactor: np.ndarray, instruction: Instruction) -> np.ndarray:
     """Apply the given step to the reactor, and return a new reactor state"""
     reactor_update = reactor.copy()
     reactor_update[
         (instruction[1][0]+50):(instruction[1][1]+51),
         (instruction[2][0]+50):(instruction[2][1]+51),
         (instruction[3][0]+50):(instruction[3][1]+51)
     ] = instruction[0]
     return reactor_update
 
 def reboot_reactor(instructions: List[Instruction]) -> np.ndarray:
     """Starting with a reactor that's turned off, apply all the steps to
     initialize the reactor"""
     return reduce(apply_step,
                   instructions,
                   np.zeros((101, 101, 101), dtype=bool))
 
 def solve_puzzle(input_string: str) -> int:
     """Return the numeric solution to the puzzle"""
     return int(reboot_reactor(parse_input(input_string)).sum())
 
 def main() -> None:
     """Run when the file is called as a script"""
     assert solve_puzzle(EXAMPLE_INPUT) == 590784
     print("Number of cubes turned on:",
           solve_puzzle(get_puzzle_input(22)))
 
 if __name__ == "__main__":
     main()