90 lines
3.7 KiB
Org Mode
90 lines
3.7 KiB
Org Mode
** --- Day 2: Rock Paper Scissors ---
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The Elves begin to set up camp on the beach. To decide whose tent gets
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to be closest to the snack storage, a giant
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[[https://en.wikipedia.org/wiki/Rock_paper_scissors][Rock Paper
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Scissors]] tournament is already in progress.
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Rock Paper Scissors is a game between two players. Each game contains
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many rounds; in each round, the players each simultaneously choose one
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of Rock, Paper, or Scissors using a hand shape. Then, a winner for that
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round is selected: Rock defeats Scissors, Scissors defeats Paper, and
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Paper defeats Rock. If both players choose the same shape, the round
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instead ends in a draw.
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Appreciative of your help yesterday, one Elf gives you an /encrypted
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strategy guide/ (your puzzle input) that they say will be sure to help
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you win. "The first column is what your opponent is going to play: =A=
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for Rock, =B= for Paper, and =C= for Scissors. The second column--"
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Suddenly, the Elf is called away to help with someone's tent.
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The second column, you reason, must be what you should play in response:
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=X= for Rock, =Y= for Paper, and =Z= for Scissors. Winning every time
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would be suspicious, so the responses must have been carefully chosen.
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The winner of the whole tournament is the player with the highest score.
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Your /total score/ is the sum of your scores for each round. The score
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for a single round is the score for the /shape you selected/ (1 for
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Rock, 2 for Paper, and 3 for Scissors) plus the score for the /outcome
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of the round/ (0 if you lost, 3 if the round was a draw, and 6 if you
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won).
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Since you can't be sure if the Elf is trying to help you or trick you,
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you should calculate the score you would get if you were to follow the
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strategy guide.
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For example, suppose you were given the following strategy guide:
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#+begin_example
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A Y
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B X
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C Z
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#+end_example
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This strategy guide predicts and recommends the following:
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- In the first round, your opponent will choose Rock (=A=), and you
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should choose Paper (=Y=). This ends in a win for you with a score of
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/8/ (2 because you chose Paper + 6 because you won).
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- In the second round, your opponent will choose Paper (=B=), and you
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should choose Rock (=X=). This ends in a loss for you with a score of
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/1/ (1 + 0).
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- The third round is a draw with both players choosing Scissors, giving
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you a score of 3 + 3 = /6/.
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In this example, if you were to follow the strategy guide, you would get
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a total score of =15= (8 + 1 + 6).
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/What would your total score be if everything goes exactly according to
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your strategy guide?/
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Your puzzle answer was =11841=.
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** --- Part Two ---
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The Elf finishes helping with the tent and sneaks back over to you.
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"Anyway, the second column says how the round needs to end: =X= means
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you need to lose, =Y= means you need to end the round in a draw, and =Z=
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means you need to win. Good luck!"
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The total score is still calculated in the same way, but now you need to
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figure out what shape to choose so the round ends as indicated. The
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example above now goes like this:
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- In the first round, your opponent will choose Rock (=A=), and you need
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the round to end in a draw (=Y=), so you also choose Rock. This gives
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you a score of 1 + 3 = /4/.
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- In the second round, your opponent will choose Paper (=B=), and you
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choose Rock so you lose (=X=) with a score of 1 + 0 = /1/.
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- In the third round, you will defeat your opponent's Scissors with Rock
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for a score of 1 + 6 = /7/.
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Now that you're correctly decrypting the ultra top secret strategy
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guide, you would get a total score of =12=.
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Following the Elf's instructions for the second column, /what would your
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total score be if everything goes exactly according to your strategy
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guide?/
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Your puzzle answer was =13022=.
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Both parts of this puzzle are complete! They provide two gold stars: **
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