### Project Euler - Problem #36

Description

The decimal number, 585 = 1001001001 (binary), is palindromic in both bases.Find the sum of all numbers, less than one million, which are palindromic in base 10 and base 2.(Please note that the palindromic number, in either base, may not include leading zeros.)

Solution (Improved)

let isPalindromicBase2 (n:int) =

let forward = System.Convert.ToString(n,2) |> Seq.map (fun c -> int c - int '0') |> Seq.toArray

let rev = Array.rev forward

if forward = rev then

true

else

false

let reverse (s:string) = new string(s |> Seq.toArray |> Array.rev)

let getPalindromesBase10 =

let base10Array = [|1..1000000|] |> Array.filter (fun x -> string x = reverse(string x))

let base02Array = base10Array |> Array.filter (fun x -> isPalindromicBase2 x)

Array.sum base02Array

Solution (Original)

let reverseToBinaryList (n:int) =

System.Convert.ToString(n,2) |> Seq.map (fun c -> int c - int '0')

…

The decimal number, 585 = 1001001001 (binary), is palindromic in both bases.Find the sum of all numbers, less than one million, which are palindromic in base 10 and base 2.(Please note that the palindromic number, in either base, may not include leading zeros.)

Solution (Improved)

let isPalindromicBase2 (n:int) =

let forward = System.Convert.ToString(n,2) |> Seq.map (fun c -> int c - int '0') |> Seq.toArray

let rev = Array.rev forward

if forward = rev then

true

else

false

let reverse (s:string) = new string(s |> Seq.toArray |> Array.rev)

let getPalindromesBase10 =

let base10Array = [|1..1000000|] |> Array.filter (fun x -> string x = reverse(string x))

let base02Array = base10Array |> Array.filter (fun x -> isPalindromicBase2 x)

Array.sum base02Array

Solution (Original)

let reverseToBinaryList (n:int) =

System.Convert.ToString(n,2) |> Seq.map (fun c -> int c - int '0')

…