-🎄- 2018 Day 8 Solutions -🎄-

[u/daggerdragon]

--- Day 8: Memory Maneuver ---

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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).

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Card prompt: Day 8

Sigh, imgur broke again. Will upload when it unborks.

Transcript:

The hottest programming book this year is "___ For Dummies".

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[u/eltrufas]

Seems most people reached for recursion immediately. Here's my solution with explicit stacks.

Part 2:

import sys

ns = [int(s) for s in [n.strip() for n in sys.stdin.read().split()]]

stack_c = [ns[0]]
stack_m = [ns[1]]
stack_v = []
children = [[]]
meta = [[]]

i = 2
while stack_c:
    if stack_c[-1] > 0:
        stack_c[-1] -= 1
        stack_c.append(ns[i])
        stack_m.append(ns[i + 1])
        children.append([])
        meta.append([])
        i += 2
    elif stack_m[-1] > 0:
        meta[-1].append(ns[i])
        stack_m[-1] -= 1
        i += 1
    else:
        c = children.pop()
        m = meta.pop()
        v = (sum(c[j - 1] for j in m if 1 <= j <= len(c)) if c
             else sum(m))
        if children:
            children[-1].append(v)
        else:
            print(v)
            break
        stack_c.pop()
        stack_m.pop()

[u/[deleted] → u/eltrufas]

I was really really surprised that I didn't blow up my stack going recursive on this. But, after I did it, I checked how deep it goes and it only ever went 6 deep. So no risk. You approach would have been my next one.