advent_of_code_2021

day11_part2.py (1891B)

---

 #!/usr/bin/env python
 """Advent of Code 2021, day 11 (part 2): Flashing octopuses
 For part 2, we're simulating bioluminescent octopuses again, and this time we
 want to find the `step` at which they all flash simultaneously."""
 
 # I think I can pretty much use everything from part 1 here and just update the
 # solving code
 
 import numpy as np
 from day11_part1 import (EXAMPLE_INPUT,
                          simulate_step)
 from utils import get_puzzle_input, convert_input_to_array
 
 def all_flashed(energy_levels: np.ndarray) -> bool:
     """Detects the moment when all energy levels have been reset to 0"""
     return not energy_levels.any()
 
 def run_simulation_until_synchronized(energy_levels: np.ndarray) -> int:
     """Run the simulation from the initial 2d array of energy levels until all
     octopuses flash at the same time, and return the step number at which it
     occurred"""
     # Leaning on Python's nice iterator behavior and for/else syntax: no need
     # to risk an infinite loop, we can set a "reasonable" limit of iterations
     # up front. Also I just love underscores in numeric literals.
     for num_steps in range(1_000_000):
         energy_levels = simulate_step(energy_levels)[0]
         if all_flashed(energy_levels):
             break
     else:
         raise RuntimeError("No synchronized flash detected after many steps")
 
     # We're counting steps from 1 apparently
     return num_steps + 1
 
 def solve_puzzle(input_string: str) -> int:
     """Return the numeric solution to the puzzle"""
     return run_simulation_until_synchronized(
         convert_input_to_array(input_string)
     )
 
 def main() -> None:
     """Run when the file is called as a script"""
     assert solve_puzzle(EXAMPLE_INPUT) == 195
     # Is that you, Shevek?
     print("Number of steps to simultaneity:",
           solve_puzzle(get_puzzle_input(11)))
 
 if __name__ == "__main__":
     main()