Write a method longest_string which takes as its input an Array of Strings and returns the longest String in the Array. For example: # 'zzzzzzz' is 7 characters long longest_string(['cat', 'zzzzzzz', 'apples']) # => "zzzzzzz" If the input Array is empty longest_string should return nil.

Find the longest string in an array

# longest_string is a method that takes an array of strings as its input
# and returns the longest string
#
# +array+ is an array of strings
# longest_string(array) should return the longest string in +array+
#
# If +array+ is empty the method should return nil
def longest_string(array)
  longest = nil
  array.each do |x|
    if longest.nil? || longest.length < x.length 
      longest = x
    end
  end
  
  longest
end