lanternfish.py

""" Advent of Code 2021. Day 6: Lanternfish """

fish = [3, 4, 3, 1, 2]
fish = [4,1,1,4,1,2,1,4,1,3,4,4,1,5,5,1,3,1,1,1,4,4,3,1,5,3,1,2,5,1,1,5,1,1,4,1,1,1,1,2,1,5,3,4,4,1,1,1,1,1,1,1,1,1,2,1,1,1,1,1,5,1,1,1,4,1,2,3,5,1,2,2,4,1,4,4,4,1,2,5,1,2,1,1,1,1,1,1,4,1,1,4,3,4,2,1,3,1,1,1,3,5,5,4,3,4,1,5,1,1,1,2,2,1,3,1,2,4,1,1,3,3,1,3,3,1,1,3,1,5,1,1,3,1,1,1,5,4,1,1,1,1,4,1,1,3,5,4,3,1,1,5,4,1,1,2,5,4,2,1,4,1,1,1,1,3,1,1,1,1,4,1,1,1,1,2,4,1,1,1,1,3,1,1,5,1,1,1,1,1,1,4,2,1,3,1,1,1,2,4,2,3,1,4,1,2,1,4,2,1,4,4,1,5,1,1,4,4,1,2,2,1,1,1,1,1,1,1,1,1,1,1,4,5,4,1,3,1,3,1,1,1,5,3,5,5,2,2,1,4,1,4,2,1,4,1,2,1,1,2,1,1,5,4,2,1,1,1,2,4,1,1,1,1,2,1,1,5,1,1,2,2,5,1,1,1,1,1,2,4,2,3,1,2,1,5,4,5,1,4]

from collections import Counter

def simulate(fish, days=80):
    fish = Counter(fish)
    for day in range(days):
        # Storing the number of spawning fishes
        new_fish = fish[0]
        # Adjusting the days until spawn
        fish = Counter({k-1: fish[k] for k in range(1, 9)})
        # Adding the spawning fishes to the 6 day group
        fish[6] += new_fish
        # Adding the spawned fishes
        fish[8] = new_fish
    return sum(fish.values())

print("Part 1:\t", simulate(fish))
print("Part 2:\t", simulate(fish, days=256))