99 lines
4.0 KiB
Plaintext
99 lines
4.0 KiB
Plaintext
Advent of Code
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--- Day 2: Inventory Management System ---
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You stop falling through time, catch your breath, and check the screen on
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the device. "Destination reached. Current Year: 1518. Current Location:
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North Pole Utility Closet 83N10." You made it! Now, to find those anomalies.
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Outside the utility closet, you hear footsteps and a voice. "...I'm not sure
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either. But now that so many people have chimneys, maybe he could sneak in
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that way?" Another voice responds, "Actually, we've been working on a new
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kind of suit that would let him fit through tight spaces like that. But, I
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heard that a few days ago, they lost the prototype fabric, the design plans,
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everything! Nobody on the team can even seem to remember important details
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of the project!"
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"Wouldn't they have had enough fabric to fill several boxes in the
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warehouse? They'd be stored together, so the box IDs should be similar. Too
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bad it would take forever to search the warehouse for two similar box
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IDs..." They walk too far away to hear any more.
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Late at night, you sneak to the warehouse - who knows what kinds of
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paradoxes you could cause if you were discovered - and use your fancy wrist
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device to quickly scan every box and produce a list of the likely candidates
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(your puzzle input).
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To make sure you didn't miss any, you scan the likely candidate boxes again,
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counting the number that have an ID containing exactly two of any letter and
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then separately counting those with exactly three of any letter. You can
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multiply those two counts together to get a rudimentary checksum and compare
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it to what your device predicts.
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For example, if you see the following box IDs:
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• abcdef contains no letters that appear exactly two or three times.
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• bababc contains two a and three b, so it counts for both.
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• abbcde contains two b, but no letter appears exactly three times.
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• abcccd contains three c, but no letter appears exactly two times.
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• aabcdd contains two a and two d, but it only counts once.
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• abcdee contains two e.
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• ababab contains three a and three b, but it only counts once.
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Of these box IDs, four of them contain a letter which appears exactly twice,
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and three of them contain a letter which appears exactly three times.
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Multiplying these together produces a checksum of 4 * 3 = 12.
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What is the checksum for your list of box IDs?
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Your puzzle answer was 6474.
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--- Part Two ---
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Confident that your list of box IDs is complete, you're ready to find the
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boxes full of prototype fabric.
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The boxes will have IDs which differ by exactly one character at the same
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position in both strings. For example, given the following box IDs:
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abcde
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fghij
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klmno
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pqrst
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fguij
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axcye
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wvxyz
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The IDs abcde and axcye are close, but they differ by two characters (the
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second and fourth). However, the IDs fghij and fguij differ by exactly one
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character, the third (h and u). Those must be the correct boxes.
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What letters are common between the two correct box IDs? (In the example
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above, this is found by removing the differing character from either ID,
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producing fgij.)
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Your puzzle answer was mxhwoglxgeauywfkztndcvjqr.
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Both parts of this puzzle are complete! They provide two gold stars: **
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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://en.wikipedia.org/wiki/Checksum
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. https://adventofcode.com/2018
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. https://adventofcode.com/2018/day/2/input
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