theburningmonk

// the base sequence of natural numbers
let naturalNumbers = Seq.unfold (fun x -> Some(x, x+1)) 1
 
// the decimal fraction 12345678910111213 as a sequence of strings
let fraction = 
    naturalNumbers 
    |> Seq.collect (fun x -> x.ToString().ToCharArray() |> Seq.map (fun c -> c.ToString()))
 
// define function d
let d n = int(fraction |> Seq.nth (n-1))

theburningmonk

open System.Linq
 
// checks if the number n is palindromic
let isPalindromic n =
    let charArray = n.ToString().ToCharArray()
    let revCharArray = Array.rev charArray
    charArray.SequenceEqual(revCharArray)
 
// reverse a number, e.g. 1234 -> 4321
let reverse n = 

theburningmonk

let digitalSum n = n.ToString().ToCharArray() |> Array.map (fun c -> int(c.ToString())) |> Array.sum
 
let answer =
    [1I..100I]
    |> List.collect (fun a -> [1..100] |> List.map (fun b -> digitalSum(pown a b)))
    |> List.max

theburningmonk

open System.Collections.Generic
 
// factorial function
let factorial n = if n = 0 then 1 else [1..n] |> List.reduce (fun acc x -> acc * x)

// create a cache of sorts to help improve performance and prepopulate them
let factorials, terms = new Dictionary<int, int>(), new Dictionary<int, int>()
terms.Add(169, 3)
terms.Add(871, 2)
terms.Add(872, 2)

theburningmonk

let digitBases = [9..-1..0] |> List.map (fun n -> pown 10 n)

/// turns the specified number into a list of its digits
let toDigits (n : int) = 
    digitBases |> List.filter (fun n' -> n > n') |> List.map (fun n' -> (n / n') % 10)

/// turns the specified list of digits into the number they represent
let toNumber (digits : int list) =
    digits |> List.mapi (fun i n -> n * pown 10 (digits.Length - i - 1)) |> List.sum

theburningmonk

open System.IO
open System.Collections.Generic

// read the keylog file into a int [] []
let entries = File.ReadAllLines(@"c:\temp\keylog.txt") 
              |> Array.map (fun str -> str.ToCharArray() |> Array.map (fun c -> int(c.ToString())))

// dictionary for keeping track of the list of numbers that falls behind a number
let inFrontOf = new Dictionary<int, int list>();

theburningmonk

open System
open System.IO

// the top 10 most common words in English
let mostCommmonWords = ["the"; "be"; "to"; "of"; "and"; "a"; "in"; "that"; "have"; "I"]

// read the encrypted ASCII codes
let cipherBytes = File.ReadAllText(@"c:\temp\cipher1.txt").Split(',') 
                  |> Array.map (fun str -> byte(str.Trim()))

theburningmonk

let taxRates = 
    [((0.0, Some(5070.0)), 0.1); 
     ((5070.0, Some(8660.0)), 0.14); 
     ((8660.0, Some(14070.0)), 0.23); 
     ((14070.0, Some(21240.0)), 0.3); 
     ((21240.0, Some(40230.0)), 0.33); 
     ((40230.0, None), 0.45)]
    
let calcTaxRate (n : float) =
    List.fold (fun acc ((lower, upper), rate) -> 

theburningmonk

// dummy method that throws an exception based on the input
public void ThrowException(int n) {
    switch (n) {
        case 0:
            throw new Exception("Default exception");
        case 1:
            throw new ArgumentException("Invalid argument");
        case 2:
            throw new ArgumentNullException();
        case 3:

theburningmonk

open System

let throwException =
    function
    | 0 -> failwithf "Default exception"
    | 1 -> raise <| new ArgumentException("Invalid N")
    | 2 -> raise <| new ArgumentNullException()
    | 3 | 4 | 5 -> raise <| new ArgumentOutOfRangeException()
    | _ -> raise <| new ApplicationException()