diff --git a/src/Year_2023/Day04.py b/src/Year_2023/Day04.py new file mode 100644 index 0000000..ca10ec5 --- /dev/null +++ b/src/Year_2023/Day04.py @@ -0,0 +1,159 @@ +# --- Day 4: Scratchcards --- + +# The gondola takes you up. Strangely, though, the ground doesn't seem to be +# coming with you; you're not climbing a mountain. As the circle of Snow Island +# recedes below you, an entire new landmass suddenly appears above you! The +# gondola carries you to the surface of the new island and lurches into the +# station. + +# As you exit the gondola, the first thing you notice is that the air here is +# much warmer than it was on Snow Island. It's also quite humid. Is this where +# the water source is? + +# The next thing you notice is an Elf sitting on the floor across the station in +# what seems to be a pile of colorful square cards. + +# "Oh! Hello!" The Elf excitedly runs over to you. "How may I be of service?" +# You ask about water sources. + +# "I'm not sure; I just operate the gondola lift. That does sound like something +# we'd have, though - this is Island Island, after all! I bet the gardener would +# know. He's on a different island, though - er, the small kind surrounded by +# water, not the floating kind. We really need to come up with a better naming +# scheme. Tell you what: if you can help me with something quick, I'll let you +# borrow my boat and you can go visit the gardener. I got all these scratchcards +# as a gift, but I can't figure out what I've won." + +# The Elf leads you over to the pile of colorful cards. There, you discover +# dozens of scratchcards, all with their opaque covering already scratched off. +# Picking one up, it looks like each card has two lists of numbers separated by +# a vertical bar (|): a list of winning numbers and then a list of numbers you +# have. You organize the information into a table (your puzzle input). + +# As far as the Elf has been able to figure out, you have to figure out which of +# the numbers you have appear in the list of winning numbers. The first match +# makes the card worth one point and each match after the first doubles the +# point value of that card. + +# For example: + +# Card 1: 41 48 83 86 17 | 83 86 6 31 17 9 48 53 +# Card 2: 13 32 20 16 61 | 61 30 68 82 17 32 24 19 +# Card 3: 1 21 53 59 44 | 69 82 63 72 16 21 14 1 +# Card 4: 41 92 73 84 69 | 59 84 76 51 58 5 54 83 +# Card 5: 87 83 26 28 32 | 88 30 70 12 93 22 82 36 +# Card 6: 31 18 13 56 72 | 74 77 10 23 35 67 36 11 + +# In the above example, card 1 has five winning numbers (41, 48, 83, 86, and 17) +# and eight numbers you have (83, 86, 6, 31, 17, 9, 48, and 53). Of the numbers +# you have, four of them (48, 83, 17, and 86) are winning numbers! That means +# card 1 is worth 8 points (1 for the first match, then doubled three times for +# each of the three matches after the first). + +# Card 2 has two winning numbers (32 and 61), so it is worth 2 points. +# Card 3 has two winning numbers (1 and 21), so it is worth 2 points. +# Card 4 has one winning number (84), so it is worth 1 point. +# Card 5 has no winning numbers, so it is worth no points. +# Card 6 has no winning numbers, so it is worth no points. + +# So, in this example, the Elf's pile of scratchcards is worth 13 points. + +# Take a seat in the large pile of colorful cards. How many points are they worth in total? + +with open("files/P4.txt") as f: + cards = [line for line in f.read().strip().split("\n")] + + +def part1(): + total = 0 + for card in cards: + game = card.split(":")[1].split("|") + winning = set(int(n) for n in game[0].split()) + hand = set(int(n) for n in game[1].split()) + + winners = list(winning & hand) + + if (winning_hand := len(winners)) == 1: + total += 1 + if winning_hand > 1: + total += pow(2, winning_hand - 1) + + print(f"There are {total} points in total") + + +# --- Part Two --- + +# Just as you're about to report your findings to the Elf, one of you realizes +# that the rules have actually been printed on the back of every card this whole +# time. + +# There's no such thing as "points". Instead, scratchcards only cause you to win +# more scratchcards equal to the number of winning numbers you have. + +# Specifically, you win copies of the scratchcards below the winning card equal +# to the number of matches. So, if card 10 were to have 5 matching numbers, you +# would win one copy each of cards 11, 12, 13, 14, and 15. + +# Copies of scratchcards are scored like normal scratchcards and have the same +# card number as the card they copied. So, if you win a copy of card 10 and it +# has 5 matching numbers, it would then win a copy of the same cards that the +# original card 10 won: cards 11, 12, 13, 14, and 15. This process repeats until +# none of the copies cause you to win any more cards. (Cards will never make you +# copy a card past the end of the table.) + +# This time, the above example goes differently: + +# Card 1: 41 48 83 86 17 | 83 86 6 31 17 9 48 53 +# Card 2: 13 32 20 16 61 | 61 30 68 82 17 32 24 19 +# Card 3: 1 21 53 59 44 | 69 82 63 72 16 21 14 1 +# Card 4: 41 92 73 84 69 | 59 84 76 51 58 5 54 83 +# Card 5: 87 83 26 28 32 | 88 30 70 12 93 22 82 36 +# Card 6: 31 18 13 56 72 | 74 77 10 23 35 67 36 11 + +# Card 1 has four matching numbers, so you win one copy each of the next +# four cards: cards 2, 3, 4, and 5. +# Your original card 2 has two matching numbers, so you win one copy each of +# cards 3 and 4. +# Your copy of card 2 also wins one copy each of cards 3 and 4. +# Your four instances of card 3 (one original and three copies) have two +# matching numbers, so you win four copies each of cards 4 and 5. +# Your eight instances of card 4 (one original and seven copies) have one +# matching number, so you win eight copies of card 5. +# Your fourteen instances of card 5 (one original and thirteen copies) have +# no matching numbers and win no more cards. +# Your one instance of card 6 (one original) has no matching numbers and +# wins no more cards. + +# Once all of the originals and copies have been processed, you end up with 1 +# instance of card 1, 2 instances of card 2, 4 instances of card 3, 8 instances +# of card 4, 14 instances of card 5, and 1 instance of card 6. In total, this +# example pile of scratchcards causes you to ultimately have 30 scratchcards! + +# Process all of the original and copied scratchcards until no more scratchcards +# are won. Including the original set of scratchcards, how many total +# scratchcards do you end up with? + + +from collections import defaultdict + +score = defaultdict(int) + + +def part2(): + for idx, card in enumerate(cards): + game = card.split(":")[1].split("|") + winning = set(int(n) for n in game[0].split()) + hand = set(int(n) for n in game[1].split()) + + winners = list(winning & hand) + + score[idx] += 1 + for i, _ in enumerate(winners): + score[idx + 1 + i] += score[idx] + + print(f"There are {sum(score.values())} scratchcards") + + +if __name__ == "__main__": + part1() + part2()