Project Euler - Problem 22

Description

• Using names.txt (right click and 'Save Link/Target As...'), a 46K text file containing over five-thousand first names, begin by sorting it into alphabetical order.
• Then working out the alphabetical value for each name, multiply this value by its alphabetical position in the list to obtain a name score.
• For example, when the list is sorted into alphabetical order, COLIN, which is worth 3 + 15 + 12 + 9 + 14 = 53, is the 938th name in the list.
• So, COLIN would obtain a score of 938 53 = 49714.
• What is the total of all the name scores in the file?

 Solution 

open System.IO

let alphaArrayValue (ch:char) =
     let alphas = [|' ';'A';'B';'C';'D';'E';'F';'G';'H';'I';'J';'K';'L';'M';'N';'O';'P';'Q';'R';'S';'T';'U';'V';'W';'X';'Y';'Z';|]

     let value = alphas |> Array.findIndex (fun x -> ch = x)

     value

let sumEachItem (item:string) =

     let charArray = item.ToCharArray()

     let value = charArray |> Array.map (fun x -> alphaArrayValue x)

     Array.sum value

let start_22 = System.DateTime.UtcNow

let newArray =
      let fileAsString = File.ReadAllText(@"C:\Documents and Settings\...\names.txt")

     let arr = fileAsString.Replace("\"","").Split(',')

     let summedItems = (Array.sort arr) |> Array.map (fun x -> sumEachItem x)

     let results = Array.create (Array.length summedItems) 0

     let result =

          for i=0 to ((Array.length summedItems)-1) do

               results.[i] <- summedItems.[i] * (i+1)

     Array.sum results

printfn "%f" ((System.DateTime.UtcNow).Subtract(start_22).TotalSeconds)