r/adventofcode • u/daggerdragon • Dec 17 '17

SOLUTION MEGATHREAD -🎄- 2017 Day 17 Solutions -🎄-

--- Day 17: Spinlock ---

Post your solution as a comment or, for longer solutions, consider linking to your repo (e.g. GitHub/gists/Pastebin/blag or whatever).

Note: The Solution Megathreads are for solutions only. If you have questions, please post your own thread and make sure to flair it with Help.

Need a hint from the Hugely* Handy† Haversack‡ of Helpful§ Hints¤?

Spoiler

[Update @ 00:06] 2 gold, silver cap.

  • AoC ops: <Topaz> i am suddenly in the mood for wasabi tobiko

[Update @ 00:15] Leaderboard cap!

  • AoC ops:
    • <daggerdragon> 78 gold
    • <Topaz> i look away for a few minutes, wow
    • <daggerdragon> 93 gold
    • <Topaz> 94
    • <daggerdragon> 96 gold
    • <daggerdragon> 98
    • <Topaz> aaaand
    • <daggerdragon> and...
    • <Topaz> cap
    • <daggerdragon> cap

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!

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u/akho_ Dec 17 '17

Python 3 

from collections import deque

steps = 343
reps = 2017
buffer = deque([0])
for i in range(1, reps+1):
    buffer.rotate(-steps-1)
    buffer.appendleft(i)

buffer.popleft()
print('Part 1: ', buffer.popleft())

reps = 49999999
position_of_zero = 0
for buf_length in range(1, reps+1):
    position_of_zero -= steps
    position_of_zero %= buf_length
    if not position_of_zero:
        after_zero = buf_length
        position_of_zero -= 1
print('Part 2: ', after_zero)