102 lines
4.7 KiB
Plaintext
102 lines
4.7 KiB
Plaintext
Advent of Code
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--- Day 14: Chocolate Charts ---
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You finally have a chance to look at all of the produce moving around. Chocolate, cinnamon, mint, chili
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peppers, nutmeg, vanilla... the Elves must be growing these plants to make hot chocolate! As you realize
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this, you hear a conversation in the distance. When you go to investigate, you discover two Elves in what
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appears to be a makeshift underground kitchen/laboratory.
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The Elves are trying to come up with the ultimate hot chocolate recipe; they're even maintaining a scoreboard
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which tracks the quality score (0-9) of each recipe.
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Only two recipes are on the board: the first recipe got a score of 3, the second, 7. Each of the two Elves
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has a current recipe: the first Elf starts with the first recipe, and the second Elf starts with the second
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recipe.
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To create new recipes, the two Elves combine their current recipes. This creates new recipes from the digits
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of the sum of the current recipes' scores. With the current recipes' scores of 3 and 7, their sum is 10, and
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so two new recipes would be created: the first with score 1 and the second with score 0. If the current
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recipes' scores were 2 and 3, the sum, 5, would only create one recipe (with a score of 5) with its single
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digit.
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The new recipes are added to the end of the scoreboard in the order they are created. So, after the first
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round, the scoreboard is 3, 7, 1, 0.
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After all new recipes are added to the scoreboard, each Elf picks a new current recipe. To do this, the Elf
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steps forward through the scoreboard a number of recipes equal to 1 plus the score of their current recipe.
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So, after the first round, the first Elf moves forward 1 + 3 = 4 times, while the second Elf moves forward 1
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+ 7 = 8 times. If they run out of recipes, they loop back around to the beginning. After the first round,
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both Elves happen to loop around until they land on the same recipe that they had in the beginning; in
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general, they will move to different recipes.
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Drawing the first Elf as parentheses and the second Elf as square brackets, they continue this process:
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(3)[7]
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(3)[7] 1 0
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3 7 1 [0](1) 0
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3 7 1 0 [1] 0 (1)
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(3) 7 1 0 1 0 [1] 2
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3 7 1 0 (1) 0 1 2 [4]
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3 7 1 [0] 1 0 (1) 2 4 5
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3 7 1 0 [1] 0 1 2 (4) 5 1
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3 (7) 1 0 1 0 [1] 2 4 5 1 5
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3 7 1 0 1 0 1 2 [4](5) 1 5 8
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3 (7) 1 0 1 0 1 2 4 5 1 5 8 [9]
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3 7 1 0 1 0 1 [2] 4 (5) 1 5 8 9 1 6
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3 7 1 0 1 0 1 2 4 5 [1] 5 8 9 1 (6) 7
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3 7 1 0 (1) 0 1 2 4 5 1 5 [8] 9 1 6 7 7
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3 7 [1] 0 1 0 (1) 2 4 5 1 5 8 9 1 6 7 7 9
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3 7 1 0 [1] 0 1 2 (4) 5 1 5 8 9 1 6 7 7 9 2
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The Elves think their skill will improve after making a few recipes (your puzzle input). However, that could
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take ages; you can speed this up considerably by identifying the scores of the ten recipes after that. For
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example:
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• If the Elves think their skill will improve after making 9 recipes, the scores of the ten recipes after
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the first nine on the scoreboard would be 5158916779 (highlighted in the last line of the diagram).
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• After 5 recipes, the scores of the next ten would be 0124515891.
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• After 18 recipes, the scores of the next ten would be 9251071085.
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• After 2018 recipes, the scores of the next ten would be 5941429882.
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What are the scores of the ten recipes immediately after the number of recipes in your puzzle input?
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Your puzzle answer was 1776718175.
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--- Part Two ---
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As it turns out, you got the Elves' plan backwards. They actually want to know how many recipes appear on the
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scoreboard to the left of the first recipes whose scores are the digits from your puzzle input.
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• 51589 first appears after 9 recipes.
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• 01245 first appears after 5 recipes.
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• 92510 first appears after 18 recipes.
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• 59414 first appears after 2018 recipes.
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How many recipes appear on the scoreboard to the left of the score sequence in your puzzle input?
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Your puzzle answer was 20220949.
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Both parts of this puzzle are complete! They provide two gold stars: **
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Your puzzle input was 290431.
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References
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Visible links
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. https://adventofcode.com/
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. https://adventofcode.com/2018/about
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. https://adventofcode.com/2018/events
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. https://adventofcode.com/2018/settings
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. https://adventofcode.com/2018/auth/logout
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. Advent of Code Supporter
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https://adventofcode.com/2018/support
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. https://adventofcode.com/2018
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. https://adventofcode.com/2018
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. https://adventofcode.com/2018/support
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. https://adventofcode.com/2018/sponsors
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. https://adventofcode.com/2018/leaderboard
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. https://adventofcode.com/2018/stats
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. https://adventofcode.com/2018/sponsors
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. https://adventofcode.com/2018
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