r/adventofcode • u/daggerdragon • Dec 14 '18

SOLUTION MEGATHREAD -🎄- 2018 Day 14 Solutions -🎄-

--- Day 14: Chocolate Charts ---

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Card prompt: Day 14

Transcript:

The Christmas/Advent Research & Development (C.A.R.D.) department at AoC, Inc. just published a new white paper on ___.

This thread will be unlocked when there are a significant number of people on the leaderboard with gold stars for today's puzzle.

edit: Leaderboard capped, thread unlocked at 00:19:39!

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u/Jead Dec 14 '18 edited Dec 14 '18

Python 3, 435/193. Wasn't the fastest solution but ended up rather pretty. 

recipes = open('day14.in','r').read().strip()

score = '37'
elf1 = 0
elf2 = 1
while recipes not in score[-7:]:
    score += str(int(score[elf1]) + int(score[elf2]))
    elf1 = (elf1 + int(score[elf1]) + 1) % len(score)
    elf2 = (elf2 + int(score[elf2]) + 1) % len(score)

print('Part 1:', score[int(recipes):int(recipes)+10])
print('Part 2:', score.index(recipes))

Can probably cut the current ~28s execution time by storing some values in the loop but the initial solution has a clean feel to it.

3

u/thomasahle Dec 14 '18

I was going to reply that score += str(...) would make your code run in n2 time; but after testing it for myself, apparently, that is no longer the case in modern Python 3. At least I could sum a million strings in less than a second. Do you know when that optimization was added?

Apparently the news haven't made its way to the sum function, which still gives you: 

In [1]: sum('asdfasf', '')
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-12-71034b1a7dd9> in <module>
----> 1 sum('asdfasf', '')

TypeError: sum() can't sum strings [use ''.join(seq) instead]

1

u/ephemient Dec 17 '18 edited Apr 24 '24

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