45 lines
1.5 KiB
Plaintext
45 lines
1.5 KiB
Plaintext
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--- Day 3: Gear Ratios ---
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You and the Elf eventually reach a gondola lift station; he says the gondola
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lift will take you up to the water source, but this is as far as he can bring
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you. You go inside.
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It doesn't take long to find the gondolas, but there seems to be a problem:
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they're not moving.
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"Aaah!"
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You turn around to see a slightly-greasy Elf with a wrench and a look of
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surprise. "Sorry, I wasn't expecting anyone! The gondola lift isn't working
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right now; it'll still be a while before I can fix it." You offer to help.
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The engineer explains that an engine part seems to be missing from the engine,
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but nobody can figure out which one. If you can add up all the part numbers in
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the engine schematic, it should be easy to work out which part is missing.
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The engine schematic (your puzzle input) consists of a visual representation of
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the engine. There are lots of numbers and symbols you don't really understand,
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but apparently any number adjacent to a symbol, even diagonally, is a "part
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number" and should be included in your sum. (Periods (.) do not count as a
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symbol.)
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Here is an example engine schematic:
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467..114..
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...*......
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..35..633.
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......#...
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617*......
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.....+.58.
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..592.....
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......755.
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...$.*....
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.664.598..
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In this schematic, two numbers are not part numbers because they are not
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adjacent to a symbol: 114 (top right) and 58 (middle right). Every other number
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is adjacent to a symbol and so is a part number; their sum is 4361.
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Of course, the actual engine schematic is much larger. What is the sum of all of
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the part numbers in the engine schematic?
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