63 lines
2.3 KiB
Markdown
63 lines
2.3 KiB
Markdown
## \-\-- Day 1: No Time for a Taxicab \-\--
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Santa\'s sleigh uses a [very high-precision
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clock]{title="An atomic clock is too inaccurate; he might end up in a wall!"}
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to guide its movements, and the clock\'s oscillator is regulated by
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stars. Unfortunately, the stars have been stolen\... by the Easter
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Bunny. To save Christmas, Santa needs you to retrieve all *fifty stars*
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by December 25th.
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Collect stars by solving puzzles. Two puzzles will be made available on
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each day in the Advent calendar; the second puzzle is unlocked when you
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complete the first. Each puzzle grants *one star*. Good luck!
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You\'re airdropped near *Easter Bunny Headquarters* in a city somewhere.
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\"Near\", unfortunately, is as close as you can get - the instructions
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on the Easter Bunny Recruiting Document the Elves intercepted start
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here, and nobody had time to work them out further.
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The Document indicates that you should start at the given coordinates
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(where you just landed) and face North. Then, follow the provided
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sequence: either turn left (`L`) or right (`R`) 90 degrees, then walk
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forward the given number of blocks, ending at a new intersection.
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There\'s no time to follow such ridiculous instructions on foot, though,
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so you take a moment and work out the destination. Given that you can
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only walk on the [street grid of the
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city](https://en.wikipedia.org/wiki/Taxicab_geometry), how far is the
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shortest path to the destination?
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For example:
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- Following `R2, L3` leaves you `2` blocks East and `3` blocks North,
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or `5` blocks away.
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- `R2, R2, R2` leaves you `2` blocks due South of your starting
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position, which is `2` blocks away.
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- `R5, L5, R5, R3` leaves you `12` blocks away.
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*How many blocks away* is Easter Bunny HQ?
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Your puzzle answer was `236`.
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## \-\-- Part Two \-\-- {#part2}
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Then, you notice the instructions continue on the back of the Recruiting
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Document. Easter Bunny HQ is actually at the first location you visit
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twice.
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For example, if your instructions are `R8, R4, R4, R8`, the first
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location you visit twice is `4` blocks away, due East.
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How many blocks away is the *first location you visit twice*?
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Your puzzle answer was `182`.
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Both parts of this puzzle are complete! They provide two gold stars:
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\*\*
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At this point, you should [return to your Advent calendar](/2016) and
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try another puzzle.
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If you still want to see it, you can [get your puzzle
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input](1/input).
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