adventofcode/2023/day07/problem

[1]Advent of Code

br0xen [7](AoC++) 14*

--- Day 7: Camel Cards ---

   Your all-expenses-paid trip turns out to be a one-way, five-minute ride in
   an [16]airship. (At least it's a cool airship!) It drops you off at the
   edge of a vast desert and descends back to Island Island.

   "Did you bring the parts?"

   You turn around to see an Elf completely covered in white clothing,
   wearing goggles, and riding a large [17]camel.

   "Did you bring the parts?" she asks again, louder this time. You aren't
   sure what parts she's looking for; you're here to figure out why the sand
   stopped.

   "The parts! For the sand, yes! Come with me; I will show you." She beckons
   you onto the camel.

   After riding a bit across the sands of Desert Island, you can see what
   look like very large rocks covering half of the horizon. The Elf explains
   that the rocks are all along the part of Desert Island that is directly
   above Island Island, making it hard to even get there. Normally, they use
   big machines to move the rocks and filter the sand, but the machines have
   broken down because Desert Island recently stopped receiving the parts
   they need to fix the machines.

   You've already assumed it'll be your job to figure out why the parts
   stopped when she asks if you can help. You agree automatically.

   Because the journey will take a few days, she offers to teach you the game
   of Camel Cards. Camel Cards is sort of similar to [18]poker except it's
   designed to be easier to play while riding a camel.

   In Camel Cards, you get a list of hands, and your goal is to order them
   based on the strength of each hand. A hand consists of five cards labeled
   one of A, K, Q, J, T, 9, 8, 7, 6, 5, 4, 3, or 2. The relative strength of
   each card follows this order, where A is the highest and 2 is the lowest.

   Every hand is exactly one type. From strongest to weakest, they are:

     • Five of a kind, where all five cards have the same label: AAAAA
     • Four of a kind, where four cards have the same label and one card has
       a different label: AA8AA
     • Full house, where three cards have the same label, and the remaining
       two cards share a different label: 23332
     • Three of a kind, where three cards have the same label, and the
       remaining two cards are each different from any other card in the
       hand: TTT98
     • Two pair, where two cards share one label, two other cards share a
       second label, and the remaining card has a third label: 23432
     • One pair, where two cards share one label, and the other three cards
       have a different label from the pair and each other: A23A4
     • High card, where all cards' labels are distinct: 23456

   Hands are primarily ordered based on type; for example, every full house
   is stronger than any three of a kind.

   If two hands have the same type, a second ordering rule takes effect.
   Start by comparing the first card in each hand. If these cards are
   different, the hand with the stronger first card is considered stronger.
   If the first card in each hand have the same label, however, then move on
   to considering the second card in each hand. If they differ, the hand with
   the higher second card wins; otherwise, continue with the third card in
   each hand, then the fourth, then the fifth.

   So, 33332 and 2AAAA are both four of a kind hands, but 33332 is stronger
   because its first card is stronger. Similarly, 77888 and 77788 are both a
   full house, but 77888 is stronger because its third card is stronger (and
   both hands have the same first and second card).

   To play Camel Cards, you are given a list of hands and their corresponding
   bid (your puzzle input). For example:

 32T3K 765
 T55J5 684
 KK677 28
 KTJJT 220
 QQQJA 483

   This example shows five hands; each hand is followed by its bid amount.
   Each hand wins an amount equal to its bid multiplied by its rank, where
   the weakest hand gets rank 1, the second-weakest hand gets rank 2, and so
   on up to the strongest hand. Because there are five hands in this example,
   the strongest hand will have rank 5 and its bid will be multiplied by 5.

   So, the first step is to put the hands in order of strength:

     • 32T3K is the only one pair and the other hands are all a stronger
       type, so it gets rank 1.
     • KK677 and KTJJT are both two pair. Their first cards both have the
       same label, but the second card of KK677 is stronger (K vs T), so
       KTJJT gets rank 2 and KK677 gets rank 3.
     • T55J5 and QQQJA are both three of a kind. QQQJA has a stronger first
       card, so it gets rank 5 and T55J5 gets rank 4.

   Now, you can determine the total winnings of this set of hands by adding
   up the result of multiplying each hand's bid with its rank (765 * 1 + 220
   * 2 + 28 * 3 + 684 * 4 + 483 * 5). So the total winnings in this example
   are 6440.

   Find the rank of every hand in your set. What are the total winnings?

   Your puzzle answer was 251287184.

--- Part Two ---

   To make things a little more interesting, the Elf introduces one
   additional rule. Now, J cards are [19]jokers - wildcards that can act like
   whatever card would make the hand the strongest type possible.

   To balance this, J cards are now the weakest individual cards, weaker even
   than 2. The other cards stay in the same order: A, K, Q, T, 9, 8, 7, 6, 5,
   4, 3, 2, J.

   J cards can pretend to be whatever card is best for the purpose of
   determining hand type; for example, QJJQ2 is now considered four of a
   kind. However, for the purpose of breaking ties between two hands of the
   same type, J is always treated as J, not the card it's pretending to be:
   JKKK2 is weaker than QQQQ2 because J is weaker than Q.

   Now, the above example goes very differently:

 32T3K 765
 T55J5 684
 KK677 28
 KTJJT 220
 QQQJA 483

     • 32T3K is still the only one pair; it doesn't contain any jokers, so
       its strength doesn't increase.
     • KK677 is now the only two pair, making it the second-weakest hand.
     • T55J5, KTJJT, and QQQJA are now all four of a kind! T55J5 gets rank 3,
       QQQJA gets rank 4, and KTJJT gets rank 5.

   With the new joker rule, the total winnings in this example are 5905.

   Using the new joker rule, find the rank of every hand in your set. What
   are the new total winnings?

   Your puzzle answer was 250757288.

   Both parts of this puzzle are complete! They provide two gold stars: **

   At this point, you should [20]return to your Advent calendar and try
   another puzzle.

   If you still want to see it, you can [21]get your puzzle input.

   You can also [Shareon [22]Twitter [23]Mastodon] this puzzle.

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  15. https://shopify.engineering/
  16. https://en.wikipedia.org/wiki/Airship
  17. https://en.wikipedia.org/wiki/Dromedary
  18. https://en.wikipedia.org/wiki/List_of_poker_hands
  19. https://en.wikipedia.org/wiki/Joker_(playing_card)
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  21. https://adventofcode.com/2023/day/7/input
  22. https://twitter.com/intent/tweet?text=I%27ve+completed+%22Camel+Cards%22+%2D+Day+7+%2D+Advent+of+Code+2023&url=https%3A%2F%2Fadventofcode%2Ecom%2F2023%2Fday%2F7&related=ericwastl&hashtags=AdventOfCode
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