74 lines
3.0 KiB
Markdown
74 lines
3.0 KiB
Markdown
## \-\-- Day 14: Reindeer Olympics \-\--
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This year is the Reindeer Olympics! Reindeer can fly at high speeds, but
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must rest occasionally to recover their energy. Santa would like to know
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which of his reindeer is fastest, and so he has them race.
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Reindeer can only either be *flying* (always at their top speed) or
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*resting* (not moving at all), and always spend whole seconds in either
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state.
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For example, suppose you have the following Reindeer:
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- Comet can fly *14 km/s for 10 seconds*, but then must rest for *127
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seconds*.
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- Dancer can fly *16 km/s for 11 seconds*, but then must rest for *162
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seconds*.
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After one second, Comet has gone 14 km, while Dancer has gone 16 km.
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After ten seconds, Comet has gone 140 km, while Dancer has gone 160 km.
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On the eleventh second, Comet begins resting (staying at 140 km), and
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Dancer continues on for a total distance of 176 km. On the 12th second,
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both reindeer are resting. They continue to rest until the 138th second,
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when Comet flies for another ten seconds. On the 174th second, Dancer
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flies for another 11 seconds.
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In this example, after the 1000th second, both reindeer are resting, and
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Comet is in the lead at *`1120`* km (poor Dancer has only gotten `1056`
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km by that point). So, in this situation, Comet would win (if the race
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ended at 1000 seconds).
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Given the descriptions of each reindeer (in your puzzle input), after
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exactly `2503` seconds, *what distance has the winning reindeer
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traveled*?
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Your puzzle answer was `2660`.
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## \-\-- Part Two \-\-- {#part2}
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Seeing how reindeer move in bursts, Santa decides he\'s not pleased with
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the old scoring system.
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Instead, at the end of each second, he awards one point to the reindeer
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currently in the lead. (If there are multiple reindeer tied for the
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lead, they each get one point.) He keeps the traditional 2503 second
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time limit, of course, as doing otherwise would be [entirely
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ridiculous]{title="It also risks choosing a duration that isn't coprime with the cycle times of each reindeer."}.
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Given the example reindeer from above, after the first second, Dancer is
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in the lead and gets one point. He stays in the lead until several
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seconds into Comet\'s second burst: after the 140th second, Comet pulls
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into the lead and gets his first point. Of course, since Dancer had been
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in the lead for the 139 seconds before that, he has accumulated 139
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points by the 140th second.
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After the 1000th second, Dancer has accumulated *`689`* points, while
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poor Comet, our old champion, only has `312`. So, with the new scoring
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system, Dancer would win (if the race ended at 1000 seconds).
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Again given the descriptions of each reindeer (in your puzzle input),
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after exactly `2503` seconds, *how many points does the winning reindeer
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have*?
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Your puzzle answer was `1256`.
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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](/2015) 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](14/input).
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