Created
May 15, 2015 20:18
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This one is quite fast. (Except for the printing, it runs in less than a microsecond)
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| let calcExpr digitCount n= | |
| let rec innerCalc n current= | |
| if current>digitCount then "" else [|" - "; ""; " + "|].[n%3] + string current + innerCalc (n/3) (current+1) | |
| "1" + innerCalc n 2 | |
| let eval digitCount n= | |
| let rec innerCalc n current (partialsum, partialnumber)= | |
| if current>digitCount then partialsum + partialnumber | |
| else | |
| let nextPartials = if n % 3 = 1 then (partialsum, partialnumber * 10 + (current * (sign partialnumber))) | |
| else (partialsum + partialnumber, current * sign ((n % 3) - 1)) | |
| innerCalc (n/3) (current+1) nextPartials | |
| innerCalc n 2 (0, 1) | |
| let solutions digitCount = seq {0 .. (pown 3 (digitCount - 1)) - 1} |> Seq.filter(fun n->eval digitCount n = 100) | |
| let generateAndPrint() = solutions 9 |> Seq.map (calcExpr 9) |> Seq.iter (printfn "%s") |
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