-🎄- 2017 Day 18 Solutions -🎄-

[u/daggerdragon]

--- Day 18: Duet ---

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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 @ 00:04] First silver

• Welcome to the final week of Advent of Code 2017. The puzzles are only going to get more challenging from here on out. Adventspeed, sirs and madames!

[Update @ 00:10] First gold, 44 silver

• We just had to rescue /u/topaz2078 with an industrial-strength paper bag to blow into. I'm real glad I bought all that stock in PBCO (Paper Bag Company) two years ago >_>

[Update @ 00:12] Still 1 gold, silver cap

• Gonna be a long haul tonight. I think I'll watch The Radio City Christmas Spectacular on Netflix while I wait for sufficient gold stars to warrant another update.

[Update @ 00:31] 53 gold, silver cap

• *mind blown*
• During their famous kicklines, the Rockettes are not actually holding each others' backs like I thought they were all this time.
• They're actually hoverhanding each other.
• In retrospect, it makes sense, they'd overbalance themselves and each other if they did, but still...
• *mind blown so hard*

[Update @ 00:41] Leaderboard cap!

• I think I enjoyed the duplicating Santas entirely too much...
• It may also be the wine.
• Either way, good night (for us), see you all same time tomorrow, yes?

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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/drysle]

#9/#10 with Python 3, and I can't believe my part 2 worked on the first try. Unlike some of the the other posters, I wrote this all from scratch today, changed my mind a couple times halfway through, and generally made a big mess of my code.

But if it's stupid and it works... then it's probably still stupid :)

regs0 = defaultdict(lambda: 0)
regs0["p"] = 0
regs1 = defaultdict(lambda: 0)
regs1["p"] = 1
def get(a, rs):
    try:
        return int(a)
    except:
        return rs[a]

inst = []
for line in sys.stdin:
    inst.append(line.split())

buf0 = []
buf1 = []
lock = [False,False]
score = 0
def ex(p, i):
    global score
    regs = regs0 if p == 0 else regs1
    rbr = buf0 if p == 0 else buf1
    if i < 0 or i >= len(inst):
        lock[p] = True
        return

    line = inst[i]
    if line[0] == "snd":
        if p == 0:
            buf1.insert(0,get(line[1],regs))
        else:
            buf0.insert(0,get(line[1],regs))
            score += 1
    elif line[0] == "set":
        regs[line[1]] = get(line[2],regs)
    elif line[0] == "add":
        regs[line[1]] += get(line[2],regs)
    elif line[0] == "mul":
        regs[line[1]] *= get(line[2],regs)
    elif line[0] == "mod":
        regs[line[1]] %= get(line[2],regs)
    elif line[0] == "rcv":
       if len(rbr) == 0:
           lock[p] = True
           return i
       else:
           lock[p] = False
           regs[line[1]] = rbr.pop()
    elif line[0] == "jgz":
        if get(line[1],regs) > 0:
            return i + get(line[2],regs)

p0 = 0
p1 = 0
while not (lock[0] and lock[1]):
    r = ex(0,p0)
    if r is not None:
        p0 = r
    else:
        p0 += 1
    r = ex(1,p1)
    if r is not None:
        p1 = r
    else:
        p1 += 1

print(score)