Day 8 Notes
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| Part 1 |
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$ elixir day8part1.exs
1528
Thoughts:
Loop detection. Have a feeling I'm supposed to detect patterns, but I decided to just store the
index of every instruction executed, and stop as soon as we visit a previously-seen instruction.
A little bit annoyed about using an if/else statement for the terminating condition. I would have
preferred to use pattern matching, but I'm not sure that's possible with a MapSet.
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| Part 2 |
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$ elixir day8part2.exs
640
Thoughts:
Adapt the algorithm from part 1 to also detect when the last command has been executed (when the
0-based index is the same as the number of commands). Renamed run_until_loop → try_boot
Iterate through all the commands, toggling each one and try executing the program to see if it completes.
Could technically skip the acc commands, but decided to just leave them in to keep the code simpler.
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| Overall Thoughts |
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I was a little concerned that this would be slow, due to it being O(n²) - togging each instruction in turn,
then executing the full instruction set, however there are only ~600 instructions, so it completes
pretty quickly.
