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Microsoft Azure Notebooks - Live code - F#, R, and Python

I was exploring Jupyter notebooks , that combines live code, markdown and data, through Microsoft's implementation, known as MS Azure Notebooks , putting together a small library of R and F# notebooks . As Microsoft's FAQ for the service describes it as : ...a multi-lingual REPL on steroids. This is a free service that provides Jupyter notebooks along with supporting packages for R, Python and F# as a service. This means you can just login and get going since no installation/setup is necessary. Typical usage includes schools/instruction, giving webinars, learning languages, sharing ideas, etc. Feel free to clone and comment... In R Azure Workbook for R - Memoisation and Vectorization Charting Correlation Matrices in R In F# Charnownes Constant in FSharp.ipynb Project Euler - Problems 18 and 67 - FSharp using Dynamic Programming
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Project Euler - Problem #16

I'm fairly happy with this, since it executes speedily, and builds on prior work solving problems.  It uses a tail-recursive function and BigInteger to find the power, and a fairly straightforward conversion of the number in to a string, which it then sums.


Description

  • 215 = 32768 and the sum of its digits is 3 + 2 + 7 + 6 + 8 = 26.
  • What is the sum of the digits of the number 2^1000?

Solution


//tail-recursive function to sum array of BigInteger
open System.Numerics
let rec productBigInt (num:BigInteger) (power:BigInteger) (max:BigInteger) (acc:BigInteger) =
    if  power = max  then
        acc  * num
    else
        productBigInt num (power + 1I) max (num * acc)


//smaller aspects of function ot solve problem
let prodResult = productBigInt 2I 1I 1000I 1I
let strCharProd = prodResult.ToString()
let lenProd = strCharProd.Length


//main to solve problem
let sumPower = 
    let prodResult = productBigInt 2I 1I 1000I 1I
    let strCharProd = prodResult.ToString()
    let max = strCharProd.Length
    let arrNum = Array.create max 0    
    for i=0 to max-1 do
        arrNum.[i] <- System.Convert.ToInt32(strCharProd.Chars(i).ToString())
    Array.sum arrNum

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