gistfile1.txt

Write a program that reads a text file that contains groups of integers
that start with the word "next". For each group, the program computes and writes out
the sum of integers in that group. There may be any number of groups. Example data set:
 
        5 89
        next
        1 1 1 1 1 1    
        next
        next
        1 1 1 1 1 1 1 1 1
        next
        10 11
        12 13
        7   8
        9
        next next
        next
 
For this data the program writes:
 
        Sum of group 1 is 6.
        Group 2 contains no data.
        Sum of group 3 is 9.
        Sum of group 4 is 70.
        Group 5 contains no data.
        Group 6 contains no data.
        Group 7 contains no data.
 
The logic of this program is quite tricky. 

gistfile2.rb

filepath = File.join(__dir__, 'data.txt')
contents = File.read(filepath)
contents = contents[/next\s*\d.+/mi].sub('next', '')
contents.gsub!(/\n/, ' ')
contents = contents.split('next').map(&:split)

contents.map! do |array|
  array.map!(&:to_i)
  array.inject { |sum, n| sum + n }
end

contents.each_with_index do |sum, i|
  if sum
    puts "Sum of group #{i+1} is #{sum}."
  else
    puts "Group #{i+1} contains no data."
  end
end