Advent of Code Day 15

"""Day 15 of Advent of Code 2020 Solution"""
from collections import defaultdict, deque


class RambunctiousRecitation:
    def __init__(self, starting_numbers: str):
        self.starting_numbers: deque[int] = deque(
            [int(n) for n in starting_numbers.split(",")]
        )
        self.current_turn: int = 0
        self.last_seen: defaultdict[int, deque[int, int]] = defaultdict(
            lambda: deque([0, 0], maxlen=2)
        )
        self.last_spoken = None
        self.seen: set[int] = set()

    def __next__(self):
        self.current_turn += 1
        if self.starting_numbers:
            spoken = self.starting_numbers.popleft()
            self.last_seen[spoken].appendleft(self.current_turn)
            self.last_spoken = spoken
            return
        if self.last_seen[self.last_spoken][-1] == 0:
            self.last_spoken = 0
            self.last_seen[self.last_spoken].appendleft(self.current_turn)
        else:
            self.last_spoken = (
                self.last_seen[self.last_spoken][0]
                - self.last_seen[self.last_spoken][-1]
            )
            self.last_seen[self.last_spoken].appendleft(self.current_turn)


def find_nth_number(starting_numbers: str, nth_number: int) -> int:
    rr = RambunctiousRecitation(starting_numbers)
    for _ in range(nth_number):
        next(rr)
    return rr.last_spoken


def part_a(file_location):
    with open(file_location, "r") as f:
        data = f.readline().strip()
    return find_nth_number(data, 2020)


def part_b(file_location):
    with open(file_location, "r") as f:
        data = f.readline().strip()
    return find_nth_number(data, 30000000)


if __name__ == "__main__":
    file_location = r"data\day15.txt"
    print(part_a(file_location))
    print(part_b(file_location))