patrick
7646fb71c3
Can't be bothered to get it faster Co-authored-by: Smaug123 <patrick+github@patrickstevens.co.uk> Reviewed-on: #19
39 lines
1.1 KiB
Forth
39 lines
1.1 KiB
Forth
namespace AdventOfCode2023
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open System
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[<RequireQualifiedAccess>]
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module List =
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let rec nTuples (n : int) (xs : 'a list) : 'a list list =
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#if DEBUG
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if n < 0 then
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raise (ArgumentException "n cannot be negative")
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#endif
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match n, xs with
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| 0, _ -> [ [] ]
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| _, [] -> []
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| _, x :: xs ->
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let withX = nTuples (n - 1) xs |> List.map (fun xs -> x :: xs)
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let withoutX = nTuples n xs
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withX @ withoutX
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let inline inclusionExclusion (sizeOf : 'a -> 'ret) (sizeOfTuple : 'a list -> 'ret) (xs : 'a list) : 'ret =
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let mutable result = List.sumBy sizeOf xs
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let mutable i = 2
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while i <= xs.Length do
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let nTuples = nTuples i xs
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let sum = List.sumBy sizeOfTuple nTuples
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if sum = LanguagePrimitives.GenericZero then
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i <- Int32.MaxValue
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else
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if i % 2 = 0 then
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result <- result - sum
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else
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result <- result + sum
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i <- i + 1
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result
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