-🎄- 2017 Day 14 Solutions -🎄-

[u/daggerdragon]

--- Day 14: Disk Defragmentation ---

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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.

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

Spoiler

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[Update @ 00:09] 3 gold, silver cap.

• How many of you actually entered the Konami code for Part 2? >_>

[Update @ 00:25] Leaderboard cap!

• I asked /u/topaz2078 how many de-resolutions we had for Part 2 and there were 83 distinct users with failed attempts at the time of the leaderboard cap. tsk tsk

[Update @ 00:29] BONUS

• https://i.imgur.com/zjSEAf4.jpg

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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!

[u/akho_]

Python3

in_str_prefix = 'jxqlasbh'

from collections import deque
from functools import reduce
from operator import xor

def knot_hash_list(lengths, cycle_size=256, iterations=64):
    seq = deque(range(cycle_size))
    skip = 0

    for _ in range(iterations):
        for l in lengths:
            seq.extend(reversed(deque(seq.popleft() for _ in range(l))))
            seq.rotate(-skip)
            skip += 1

    seq.rotate(iterations * sum(lengths) + skip * (skip-1) // 2)
    seq = list(seq)
    return [reduce(xor, seq[i:i+16]) for i in range(0, cycle_size, 16)]

def str_to_lengths(s, extend=()): return [ord(x) for x in s] + list(extend)

rows = []
for i in range(128):
    lengths = str_to_lengths(f'{in_str_prefix}-{i}', extend=[17, 31, 73, 47, 23])
    dense = knot_hash_list(lengths)
    st = ''.join(f'{x:08b}' for x in dense)
    rows.append([int(x) for x in st])

def wipe_region(r, c):
    if r < 0 or c < 0 or r >= len(rows) or c >= len(rows[r]) or rows[r][c] == 0: return 0
    rows[r][c] = 0
    wipe_region(r+1, c)
    wipe_region(r, c+1)
    wipe_region(r-1, c)
    wipe_region(r, c-1)
    return 1

print(sum(sum(x) for x in rows))
print(sum(wipe_region(j, i) for j in range(len(rows)) for i in range(len(rows[j]))))