PartsOfList.rb

=begin

Write a function partlist that gives all the ways to divide a list (an array)
of at least two elements into two non-empty parts.

Each two non empty parts will be in a pair (or an array for languages without
tuples or a structin C - C: see Examples test Cases - )
Each part will be in a string
Elements of a pair must be in the same order as in the original array.
Example:

a = ["az", "toto", "picaro", "zone", "kiwi"] -->

[["az", "toto picaro zone kiwi"], ["az toto", "picaro zone kiwi"],
["az toto picaro", "zone kiwi"], ["az toto picaro zone", "kiwi"]]

or

a = {"az", "toto", "picaro", "zone", "kiwi"} -->

{{"az", "toto picaro zone kiwi"}, {"az toto", "picaro zone kiwi"},
{"az toto picaro", "zone kiwi"}, {"az toto picaro zone", "kiwi"}}

or

a = ["az", "toto", "picaro", "zone", "kiwi"] -->

[("az", "toto picaro zone kiwi"), ("az toto", "picaro zone kiwi"),
("az toto picaro", "zone kiwi"), ("az toto picaro zone", "kiwi")]

or

a = [|"az", "toto", "picaro", "zone", "kiwi"|] -->

[("az", "toto picaro zone kiwi"), ("az toto", "picaro zone kiwi"),
("az toto picaro", "zone kiwi"), ("az toto picaro zone", "kiwi")]

You can see other examples for each language in "Your test cases"

=end

# My Solution
def partlist(arr)
  result = []
  0.upto(arr.length-2) do |i|
    result << [arr[0..i].join(" "), arr[i+1..-1].join(" ")]
  end
  result
end

# Better Solution
def partlist(arr)
    (1...arr.size).map { |i|
      [arr.take(i).join(' '), arr.drop(i).join(' ')]
    }
end

# Another Solution
def partlist(arr)
  (1...arr.size).map { |n| [arr.first(n).join(" "), arr.last(arr.size - n).join(" ")] }
end