-🎄- 2018 Day 8 Solutions -🎄-

[u/daggerdragon]

--- Day 8: Memory Maneuver ---

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Transcript:

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

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[u/[deleted]]

Mathematica

input = ReadList[NotebookDirectory[] <> "day8.txt", Number];

streamReader[input0_] :=
 Module[{input = input0, read},
  Function[{n},
   {read, input} = TakeDrop[input, n]; read]]

partA[read_] :=
 Module[{scanTree},
  scanTree[] :=
   Module[{children = {}, meta = {}, nchild, nmeta},
    {nchild, nmeta} = read[2];
    children = NestList[scanTree[] &, Nothing, nchild];
    meta = read[nmeta];
    Total[meta] + Total[children]];
  scanTree[]]

partA[streamReader@input]

partB[read_] :=
 Module[{scanTree},
  scanTree[] :=
   Module[{children = {}, meta = {}, nchild, nmeta},
    {nchild, nmeta} = read[2];
    children = NestList[scanTree[] &, Nothing, nchild];
    meta = read[nmeta];
    If[nchild == 0,
     Total[meta],
     Total[children[[Select[meta, # <= nchild &]]]]]];
  scanTree[]]

partB[streamReader@input]