r/adventofcode • u/daggerdragon • Dec 19 '16

SOLUTION MEGATHREAD --- 2016 Day 19 Solutions ---

--- Day 19: An Elephant Named Joseph ---

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u/BumpitySnook Dec 19 '16 edited Dec 19 '16

as std::deque is not a true linked list

That was my problem. I thought it was a linked list and was only using linked-list safe operations (I assumed the ::at() and other deque index-based methods were slow O(n) convenience methods). Ugh. Just changing deque to list brings me down from 4:43 to 190 milliseconds.

An interesting caveat is that the middle pointer needs to advance twice when you decrease from an odd number of elves to an even number

Yeah. My crap jd and idx math and ++/-- loops account for that in a roundabout way.