adventofcode2021/aoc6-2.py

class LanternfishSchool:
    def __init__(self, counts, size_inc=100000):
        self.time_left = {}
        self.time_left["ttr"] = 0
        for i in range(9):
            self.time_left[i] = counts.count(i)
        self.size_inc = size_inc
        self.size_base = size_inc

    def age(self):
        self.time_left["ttr"] = self.time_left[0]
        for i in range(1,9):
            self.time_left[i-1] = self.time_left[i]
        self.time_left[8] = self.time_left["ttr"]
        self.time_left[6] += self.time_left["ttr"]
        self.time_left["ttr"] = 0
        if self.school_size() >= self.size_base:
            print(f"School size now {self.school_size()}.")

    def school_size(self):
        total = 0
        for _,v in self.time_left.items():
            total += v
        return total

def main():
    # The old version gets untenable above about 100 days.
    # Trying a different approach.
    num_days = 256
    with open("aoc6-1.txt", "r") as file:
        fish_ages = [int(age) for age in file.readlines()[0].split(",")]

    lfs = LanternfishSchool(fish_ages)
    for _ in range(num_days):
        lfs.age()
    print(lfs.school_size())

if __name__ == "__main__":
    main()