Challenge 1: "Create a script to demonstrate Ackermann function. The
Ackermann function is defined as below, m and n are positive number:

      A(m, n) = n + 1                  if m = 0
      A(m, n) = A(m - 1, 1)            if m > 0 and n = 0
      A(m, n) = A(m - 1, A(m, n - 1))  if m > 0 and n > 0

eg. A(1, 2) = A(0, A(1, 1))
         = A(0, A(0, A(1, 0)))
         = A(0, A(0, A(0, 1)))
         = A(0, A(0, 2))
         = A(0, 3)
         = 4
"

My notes:

Clearly described.  I seem to recall that the Ackermann function is
tremendously inefficient to calculate recursively, but that memoization
really helps.  So, before writing a line of code, I think "use Memoize"
is going to help..


Challenge 2: "Create a script to parse URL and print the components of
URL. According to the Wiki page https://en.wikipedia.org/wiki/URL, the URL
syntax is as below:

    scheme:[//[userinfo@]host[:port]]path[?query][#fragment]

eg.  jdbc://user:password@localhost:3306/pwc?profile=true#h1

      scheme:   jdbc
      userinfo: user:password
      host:     localhost
      port:     3306
      path:     /pwc
      query:    profile=true
      fragment: h1

My notes: sounds pretty trivial for regexes, if the lexical syntax of
each component is defined clearly.  Ok, reading the above wiki page
doesn't make it 100% clear, but let's hack it up, that's probably good
enough for most cases.