82 lines
3.0 KiB
Plaintext
82 lines
3.0 KiB
Plaintext
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# Advent of Code
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--- Day 1: Report Repair ---
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After saving Christmas five years in a row, you've decided to take a vacation at a nice
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resort on a tropical island. Surely, Christmas will go on without you.
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The tropical island has its own currency and is entirely cash-only. The gold coins used
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there have a little picture of a starfish; the locals just call them stars. None of the
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currency exchanges seem to have heard of them, but somehow, you'll need to find fifty of
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these coins by the time you arrive so you can pay the deposit on your room.
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To save your vacation, you need to get 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
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Advent calendar; the second puzzle is unlocked when you complete the first. Each puzzle
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grants one star. Good luck!
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Before you leave, the Elves in accounting just need you to fix your expense report (your
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puzzle input); apparently, something isn't quite adding up.
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Specifically, they need you to find the two entries that sum to 2020 and then multiply
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those two numbers together.
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For example, suppose your expense report contained the following:
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1721
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979
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366
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299
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675
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1456
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In this list, the two entries that sum to 2020 are 1721 and 299. Multiplying them together
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produces 1721 * 299 = 514579, so the correct answer is 514579.
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Of course, your expense report is much larger. Find the two entries that sum to 2020; what
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do you get if you multiply them together?
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Your puzzle answer was 157059.
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--- Part Two ---
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The Elves in accounting are thankful for your help; one of them even offers you a starfish
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coin they had left over from a past vacation. They offer you a second one if you can find
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three numbers in your expense report that meet the same criteria.
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Using the above example again, the three entries that sum to 2020 are 979, 366, and 675.
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Multiplying them together produces the answer, 241861950.
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In your expense report, what is the product of the three entries that sum to 2020?
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Your puzzle answer was 165080960.
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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 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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. https://adventofcode.com/
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. https://adventofcode.com/2020/about
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. https://adventofcode.com/2020/events
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. https://adventofcode.com/2020/settings
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. https://adventofcode.com/2020/auth/logout
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. Advent of Code Supporter
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https://adventofcode.com/2020/support
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. https://adventofcode.com/2020
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. https://adventofcode.com/2020
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. https://adventofcode.com/2020/support
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. https://adventofcode.com/2020/sponsors
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. https://adventofcode.com/2020/leaderboard
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. https://adventofcode.com/2020/stats
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. https://adventofcode.com/2020/sponsors
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. https://github.com/
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. https://adventofcode.com/events
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. https://adventofcode.com/2020
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. https://adventofcode.com/2020/day/1/input
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