63 lines
2.4 KiB
Markdown
63 lines
2.4 KiB
Markdown
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# Day 1: Trebuchet?!
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Something is wrong with global snow production, and you've been selected to take a look.
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The Elves have even given you a map; on it, they've used stars to mark the top fifty locations
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that are likely to be having problems.
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You've been doing this long enough to know that to restore snow operations,
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you need to check all fifty stars by December 25th.
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Collect stars by solving puzzles. Two puzzles will be made available on each day in the Advent calendar;
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the second puzzle is unlocked when you complete the first. Each puzzle grants one star. Good luck!
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You try to ask why they can't just use a weather machine ("not powerful enough")
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and where they're even sending you ("the sky") and why your map looks mostly blank
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("you sure ask a lot of questions") and hang on did you just say the sky
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("of course, where do you think snow comes from") when you realize that the Elves
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are already loading you into a trebuchet ("please hold still, we need to strap you in").
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As they're making the final adjustments, they discover that their calibration document
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(your puzzle input) has been amended by a very young Elf who was apparently just excited to show off
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her art skills. Consequently, the Elves are having trouble reading the values on the document.
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The newly-improved calibration document consists of lines of text;
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each line originally contained a specific calibration value that the Elves now need to recover.
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On each line, the calibration value can be found by combining the first digit and the last digit
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(in that order) to form a single two-digit number.
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For example:
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```
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1abc2
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pqr3stu8vwx
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a1b2c3d4e5f
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treb7uchet
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```
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In this example, the calibration values of these four lines are `12`, `38`, `15`, and `77`.
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Adding these together produces `142`.
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Consider your entire calibration document. What is the sum of all of the calibration values?
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## Part Two
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Your calculation isn't quite right. It looks like some of the digits are actually spelled out with letters:
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`one`, `two`, `three`, `four`, `five`, `six`, `seven`, `eight`, and `nine` also count as valid "digits".
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Equipped with this new information, you now need to find the real first and last digit on each line. For example:
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```
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two1nine
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eightwothree
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abcone2threexyz
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xtwone3four
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4nineeightseven2
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zoneight234
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7pqrstsixteen
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```
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In this example, the calibration values are `29`, `83`, `13`, `24`, `42`, `14`, and `76`.
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Adding these together produces `281`.
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What is the sum of all of the calibration values?
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