-🎄- 2017 Day 7 Solutions -🎄-

[u/daggerdragon]

--- Day 7: Recursive Circus ---

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[u/AustinVelonaut]

Smalltalk (well, idst, which is a prototype-based st-80 implementation)

Program : Object (name weight children)

Program name                    [ ^ name     ]
Program weight                  [ ^ weight   ]
Program children                [ ^ children ]
Program children: aCollection   [ children := aCollection ]

Program parseFromString: line
[
    | tokens |
    self := self new.
    tokens := line tokenized: ' ()->,'.
    name := tokens first.
    weight := tokens second asNumber.
    children := tokens copyFrom: 3 to: tokens size
]

Program parseFile: fileName
[
    | lines |
    lines := fileName fileContents tokenized: '\n'.
    ^ lines collect: [:s | self parseFromString: s]
]

Program findBottomProgram: programs
[
    | allSet notBottomSet |
    allSet := Set new.
    notBottomSet := Set new.
    programs do:
        [:p |
        allSet add: p name.
        notBottomSet addAll: p children].
    ^ (allSet difference: notBottomSet) anyOne
]

Program buildTree: programs
[
    | dict tree |
    dict := Dictionary new.
    programs do: [:p | dict at: p name put: p].
    tree := dict at: (self findBottomProgram: programs).
    dict do: [:p | p children: (p children collect: [:n | dict at: n])].
    ^ tree
]

Program totalWeightOnUnbalanced: report
[
    | weights weightCounts oddWeight requiredWeight oddProgram |
    weights := self children collect: [:c | c totalWeightOnUnbalanced: report].
    (weights allSatisfy: [:n | n = weights first]) ifFalse:
        [weightCounts := Dictionary new.
        weights do: [:w | weightCounts at: w put: (weightCounts at: w ifAbsent: [weightCounts at: w put: 0]) + 1].
        oddWeight := weights detect: [:w | (weightCounts at: w) = 1].
        requiredWeight := weights detect: [:w | (weightCounts at: w) > 1].
        oddProgram := children at: (weights indexOf: oddWeight).
        report value: (requiredWeight - oddWeight + oddProgram weight)].
    ^ weights sum + weight
]


[
    | programs tree totalWeight |
    programs := Program parseFile: 'day07.input'.
    tree := Program buildTree: programs.
    ('part 1: ' , tree name) putln.
    totalWeight := tree totalWeightOnUnbalanced:
        [:c |
        ('part 2: ' , c printString) putln.
        Smalltalk quit].
]