44 lines
1.5 KiB
Text
44 lines
1.5 KiB
Text
Day 17 Notes
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+--------+
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| Part 1 |
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+--------+
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$ elixir day17part1.exs
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362
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Thoughts:
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The answer is not pretty, but it works.
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Rather than iterate through the entire coordinate plane, which would require keeping track of where
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the current extremities are, I decided to only keep the set of active cubes around. Then for each
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iteration, check all the active cube's neighbours.
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In addition to counting the neighbours for the active cube, keep track of the inactive neighbours,
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then check *their* neighbours too to see if they should become active.
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+--------+
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| Part 2 |
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+--------+
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$ elixir day17part2.exs
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1980
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Thoughts:
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In Part 1 I was half expecting a high iteration count for part 2, hence why I avoided iterating the
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entire plane. Instead, adding a 4th dimension was a two-line change :-)
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+------------------+
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| Overall Thoughts |
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+------------------+
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Nice to have a quick Part 2 solve after day 18 which took me ages. I probably dug myself into
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a hole on day 18 though and should have took a step back and tried with a clearer mind.
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I spent quite a while getting distracted by the examples, because they present a sliding plane.
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Turns out I had actually written the correct implementation, I just struggled to translate my
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coordinates to the graphical examples. Running the script produced the correct answer though, but
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I cross-referenced it with one of the confusing examples, just in case it wasn't pure luck. I'm
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glad I was able to solve Part 2 without reading all the dreaded 4D examples there too!
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