AoC2020-day22pt2

day22.py

from typing import List


def parse_decks(f):
    player1_deck = []
    player2_deck = []
    current_deck = player1_deck
    for line in f.readlines():
        if line == '' or line == "\n" or line.lower().startswith('player 1'):
            continue
        if line.lower().startswith('player 2'):
            current_deck = player2_deck
            continue
        current_deck.append(int(line.strip()))

    return player1_deck, player2_deck


def cycle_with_idx(deck, starting_idx):
    while True:
        if starting_idx >= len(deck):
            starting_idx = 0
        for idx in range(starting_idx, len(deck)):
            yield idx, deck[idx]
        starting_idx = 0


def add_to_end(deck, idx, item):
    deck.insert(idx, item)
    return idx + 1


def calc_score(deck, gen):
    multiplier = len(deck)
    total = 0
    while multiplier > 0:
        idx, card = next(gen)
        print(f'multi {multiplier} * card {card}')
        total += multiplier * card
        multiplier -= 1
    return total


def get_game_id(deck, idx, deck2, idx2):
    return f'{str(idx)}-{",".join([str(item) for item in deck])} against {str(idx2)}-{",".join([str(item) for item in deck2])}'


def deck_in_order(deck, idx):
    gen = cycle_with_idx(deck, idx)
    return [next(gen)[1] for x in range(0, len(deck))]

def play_rounds(deck1: List[int], deck2: List[int], p1_starting_idx=0, p2_starting_idx=0):
    game_id = get_game_id(deck1, p1_starting_idx, deck2, p2_starting_idx)
    gen1 = cycle_with_idx(deck1, p1_starting_idx)
    gen2 = cycle_with_idx(deck2, p2_starting_idx)
    round_num = 1
    previous_round_ids = set()
    while len(deck1) > 0 and len(deck2) > 0:
        round_id = get_game_id(deck1, 0, deck2, 0)
        if round_id in previous_round_ids:
            return 1, 0
        previous_round_ids.add(round_id)
        p1_idx, p1_card = next(gen1)
        p2_idx, p2_card = next(gen2)
        print(f'ROUND: {round_num} -- game_id: {game_id}')
        print(f'before deck1: {deck_in_order(deck1, p1_idx)}')
        print(f'before deck2: {deck_in_order(deck2, p2_idx)}')
        print(f'p1_idx: {p1_idx} p1_card:{p1_card}')
        print(f'p2_idx: {p2_idx} p2_card:{p2_card}')

        def handle_p1_wins():
            nonlocal p1_idx
            nonlocal gen1
            nonlocal gen2
            print('p1 wins')
            deck2.pop(p2_idx)
            add_to_end(deck1, p1_idx + 1, p2_card)
            p1_idx += 2
            gen1 = cycle_with_idx(deck1, p1_idx)
            gen2 = cycle_with_idx(deck2, p2_idx)

        def handle_p2_wins():
            nonlocal p2_idx
            nonlocal gen1
            nonlocal gen2
            print('p2 wins')
            deck1.pop(p1_idx)
            add_to_end(deck2, p2_idx + 1, p1_card)
            p2_idx += 2
            gen1 = cycle_with_idx(deck1, p1_idx)
            gen2 = cycle_with_idx(deck2, p2_idx)

        if len(deck1) - 1 >= p1_card and len(deck2) - 1 >= p2_card:
            gen1_recurse = cycle_with_idx(deck1, p1_idx + 1)
            gen2_recurse = cycle_with_idx(deck2, p2_idx + 1)
            deck1_recurse = [next(gen1_recurse)[1] for _ in range(0, p1_card)]
            deck2_recurse = [next(gen2_recurse)[1] for _ in range(0, p2_card)]

            winner, score = play_rounds(deck1_recurse, deck2_recurse, 0, 0)

            if winner == 1:
                handle_p1_wins()
            else:
                handle_p2_wins()

        elif p1_card > p2_card:
            handle_p1_wins()
        elif p1_card < p2_card:
            handle_p2_wins()

        round_num += 1
        print('-------------------------------')
    if len(deck1) == 0:
        return 2, calc_score(deck2, gen2)
    return 1, calc_score(deck1, gen1)


def day22():
    with open('day22input.txt', 'r') as f:
        deck1, deck2 = parse_decks(f)
        print(deck1)
        print(deck2)
        print(play_rounds(deck1, deck2))


if __name__ == '__main__':
    day22()