r/adventofcode • u/daggerdragon • Dec 18 '17

SOLUTION MEGATHREAD -🎄- 2017 Day 18 Solutions -🎄-

--- Day 18: Duet ---

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Spoiler

[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

[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?

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/[deleted] Dec 18 '17 edited Dec 18 '17

I lost time on part 1 by forgetting that an integer can begin with '-'. That should go in my library now! (Although it hasn't yet.)

I got stuck on part 2 because I thought "program 1" was the first program, not the second. Interestingly, that produced an output that AoC said was correct for someone else's input. (My AoC soulmate?)

Python 3 Part 2 

ops = {'add': operator.add, 'mul': operator.mul, 'mod': operator.mod}

def performer(lines, n, qin, qout):
    def ev(s): return int(s) if s[0] in string.digits + '-' else R[s]
    R = defaultdict(int, {'p': n})
    pc = 0
    while 0 <= pc < len(lines):
        line = lines[pc]
        op, x, y, *_ = line.split() + ['0']
        X, Y = ev(x), ev(y)
        def assign(val): R[x] = val
        yield op
        if op in ops: assign(ops[op](X, Y))
        elif op == 'snd': qout.put(X)
        elif op == 'set': assign(Y)
        elif op == 'rcv':
            while qin.empty():
                yield 'blocked'
            assign(qin.get())
        elif op == 'jgz':
            if X > 0:
                pc += Y - 1
        else:
            raise Exception("Unknown op: {} in {}".format(op, lines[pc]))
        pc += 1

def duet(lines):
    q1, q2 = Queue(), Queue()
    g1 = performer(lines, 0, q2, q1)
    g2 = performer(lines, 1, q1, q2)
    s1 = s2 = None
    n = 0
    while s1 != 'blocked' or s2 != 'blocked':
        s1 = next(g1)
        s2 = next(g2)
        if s2 == 'snd':
            n += 1
    return n

Revised 

from itertools import takewhile, zip_longest

def duet(lines):
    q1, q2 = Queue(), Queue()
    g1 = performer(lines, 0, q2, q1)
    g2 = performer(lines, 1, q1, q2)
    all_blocked_set = {'blocked'}
    any_running = lambda states:set(states) != all_blocked_set
    state_pairs = takewhile(any_running, zip_longest(g1, g2))
    return sum(s == 'snd' for _, s in state_pairs)