61 lines
2.2 KiB
Smalltalk
61 lines
2.2 KiB
Smalltalk
Object subclass: Monkey [
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| history |
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history: h [history := h]
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lastValue [^history at: history size]
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collectPricesInto: intoTbl seen: seenTbl
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[ | ch prices deltas key newV prevSeen localBest |
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prices := history collect: [:it | it \\ 10].
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deltas := 2 to: history size collect: [
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:i | (prices at: i) - (prices at: i - 1) + 9].
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ch := 0. "past four deltas as a base-19 integer"
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1 to: 4 do: [:i | ch := 19 * ch + (deltas at: i)].
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"Accumulate the best value globally, (local variable as a
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'compiler' optimisation)."
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localBest := Monkey bestBananas.
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5 to: deltas size do: [
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:i | ch := (19 * ch + (deltas at: i)) \\ 130321.
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"ch is theoretically in the range [0,19^4),
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so add 1 to keep it in array range"
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key := ch + 1.
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(seenTbl at: key) == self ifFalse: [
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seenTbl at: key put: self.
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newV := (prices at: i + 1) + (intoTbl at: key).
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intoTbl at: key put: newV.
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newV > localBest ifTrue: [localBest := newV].
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]].
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Monkey bestBananas: localBest. ]
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]
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Monkey class extend [
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| bestV |
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bestBananas: v [bestV := v]
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bestBananas [^bestV]
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initialize [bestV := 0]
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keyDigits [^19]
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keyMax [^130321 "19 raisedTo: 4"]
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stepSecret: initial times: n
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[ | s hist | s := initial.
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hist := 1 to: n collect: [
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:i |
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s := (s bitXor: (s bitShift: 6)) bitAnd: 16777215.
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s := (s bitXor: (s bitShift: -5)) bitAnd: 16777215.
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s := (s bitXor: (s bitShift: 11)) bitAnd: 16777215.
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s ].
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^Monkey new history: {initial},hist ]
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]
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Monkey initialize.
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AOC input: [ stdin toLines collect: [
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:it | Monkey stepSecret: it asNumber times: 2000] ];
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part1: [ :monkeys | (monkeys collect: [:it | it lastValue]) sum ];
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part2: [ :monkeys | | buyMap seenMap |
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buyMap := Array new: Monkey keyMax withAll: 0.
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seenMap := Array new: Monkey keyMax withAll: nil.
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monkeys do: [:it | it collectPricesInto: buyMap seen: seenMap].
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Monkey bestBananas ];
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result: [ :monkeys :part | part value: monkeys ];
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finish.
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