2023 - Day 1

2023/01/PART1.md

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+--- Day 1: Trebuchet?! ---
+
+Something is wrong with global snow production, and you've been selected to take
+a look. The Elves have even given you a map; on it, they've used stars to mark
+the top fifty locations that are likely to be having problems.
+
+You've been doing this long enough to know that to restore snow operations, you
+need to check all fifty stars by December 25th.
+
+Collect stars by solving puzzles. Two puzzles will be made available on each day
+in the Advent calendar; the second puzzle is unlocked when you complete the
+first. Each puzzle grants one star. Good luck!
+
+You try to ask why they can't just use a weather machine ("not powerful enough")
+and where they're even sending you ("the sky") and why your map looks mostly
+blank ("you sure ask a lot of questions") and hang on did you just say the sky
+("of course, where do you think snow comes from") when you realize that the
+Elves are already loading you into a trebuchet ("please hold still, we need to
+strap you in").
+
+As they're making the final adjustments, they discover that their calibration
+document (your puzzle input) has been amended by a very young Elf who was
+apparently just excited to show off her art skills. Consequently, the Elves are
+having trouble reading the values on the document.
+
+The newly-improved calibration document consists of lines of text; each line
+originally contained a specific calibration value that the Elves now need to
+recover. On each line, the calibration value can be found by combining the first
+digit and the last digit (in that order) to form a single two-digit number.
+
+For example:
+
+```
+1abc2
+pqr3stu8vwx
+a1b2c3d4e5f
+treb7uchet
+```
+
+In this example, the calibration values of these four lines are 12, 38, 15,
+and 77. Adding these together produces 142.
+
+Consider your entire calibration document. What is the sum of all of the
+calibration values?