90 lines
3.0 KiB
Plaintext
90 lines
3.0 KiB
Plaintext
Advent of Code
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--- Day 5: Doesn't He Have Intern-Elves For This? ---
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Santa needs help figuring out which strings in his text file are naughty or
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nice.
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A nice string is one with all of the following properties:
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• It contains at least three vowels (aeiou only), like aei, xazegov, or
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aeiouaeiouaeiou.
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• It contains at least one letter that appears twice in a row, like xx,
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abcdde (dd), or aabbccdd (aa, bb, cc, or dd).
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• It does not contain the strings ab, cd, pq, or xy, even if they are part
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of one of the other requirements.
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For example:
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• ugknbfddgicrmopn is nice because it has at least three vowels
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(u...i...o...), a double letter (...dd...), and none of the disallowed
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substrings.
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• aaa is nice because it has at least three vowels and a double letter,
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even though the letters used by different rules overlap.
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• jchzalrnumimnmhp is naughty because it has no double letter.
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• haegwjzuvuyypxyu is naughty because it contains the string xy.
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• dvszwmarrgswjxmb is naughty because it contains only one vowel.
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How many strings are nice?
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Your puzzle answer was 255.
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--- Part Two ---
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Realizing the error of his ways, Santa has switched to a better model of
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determining whether a string is naughty or nice. None of the old rules
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apply, as they are all clearly ridiculous.
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Now, a nice string is one with all of the following properties:
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• It contains a pair of any two letters that appears at least twice in the
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string without overlapping, like xyxy (xy) or aabcdefgaa (aa), but not
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like aaa (aa, but it overlaps).
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• It contains at least one letter which repeats with exactly one letter
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between them, like xyx, abcdefeghi (efe), or even aaa.
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For example:
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• qjhvhtzxzqqjkmpb is nice because is has a pair that appears twice (qj)
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and a letter that repeats with exactly one letter between them (zxz).
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• xxyxx is nice because it has a pair that appears twice and a letter that
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repeats with one between, even though the letters used by each rule
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overlap.
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• uurcxstgmygtbstg is naughty because it has a pair (tg) but no repeat
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with a single letter between them.
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• ieodomkazucvgmuy is naughty because it has a repeating letter with one
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between (odo), but no pair that appears twice.
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How many strings are nice under these new rules?
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Your puzzle answer was 55.
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Both parts of this puzzle are complete! They provide two gold stars: **
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At this point, you should return to your advent calendar and try another
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puzzle.
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If you still want to see it, you can get your puzzle input.
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References
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Visible links
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. http://adventofcode.com/
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. http://adventofcode.com/about
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. http://adventofcode.com/stats
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. http://adventofcode.com/leaderboard
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. http://adventofcode.com/settings
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. http://adventofcode.com/auth/logout
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. http://adventofcode.com/
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. http://adventofcode.com/day/5/input
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