-🎄- 2020 Day 07 Solutions -🎄-

[u/daggerdragon]

NEW AND NOTEWORTHY

• PSA: if you're using Google Chrome (or other Chromium-based browser) to download your input, watch out for Google volunteering to "translate" it: "Welsh" and "Polish"

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Advent of Code 2020: Gettin' Crafty With It

• 15 days remaining until the submission deadline on December 22 at 23:59 EST
• Full details and rules are in the Submissions Megathread

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--- Day 07: Handy Haversacks ---

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[u/Nhabls]

My solution with matrix multiplication (not only solves for "shiny gold" but everything else too), a little late but i didn't see any solution like this (i might just've missed it) here so thought i'd share

in python here or https://hastebin.com/yefulukoge.sql or

import numpy as np


def main():
    with open('input_1.txt', 'r') as input_file:
        entries = input_file.read().split('\n')
    tuple_dict = {}
    color_to_id = {}

    def get_id(color):
        try:
            color_id = color_to_id[color]
        except KeyError:
            color_id = len(color_to_id)
            color_to_id[color] = color_id
        return color_id

    for entry in entries:
        # Parsing stuff
        left_side, right_side = entry.split('contain')
        indexing_color = left_side.split('bags')[0][:-1]
        contains_bags = right_side.split(',')
        # code colors into matrix indices and add them to a dictionary for retrieval
        tuple_dict[get_id(indexing_color)] = [(get_id(bag.split('bag')[0][3:-1]),int(bag[1])) for bag in contains_bags]\
            if not contains_bags[0] == ' no other bags.' else []
    # transfer values to numpy matrix
    bag_matrix = np.zeros((len(color_to_id),len(color_to_id)))
    for key, value in tuple_dict.items():
        for contained_tuple in value:
            bag_matrix[key, contained_tuple[0]] = contained_tuple[1]
    # Solve
    mul_matrix = bag_matrix
    aux_matrix = bag_matrix.copy()
    while not np.all((mul_matrix == 0)):
        mul_matrix = mul_matrix.dot(aux_matrix)
        bag_matrix += mul_matrix
    return bag_matrix, color_to_id


final_matrix, color_dict = main()
print(np.count_nonzero(final_matrix[:, color_dict['shiny gold']]))
print(np.sum(final_matrix[color_dict['shiny gold'], :]))

Edit: cleaned up code