Wsrtjtyk

I need to make a list of numbers.
Rules:

1. 12 numbers in a string;


2. First number its always "1";


3. Numbers 2-3 its an items from array = [05..15];


4. 4-5 its always "78";


5. 6-7 its an items from array = [02,03,04,07,08,09,10,11,12,15..27];


6. 8-12 its all options of five-digit numbers;

I wrote this code:

file = File.new('./file.txt', 'w')

one = 1



(5..15).to_a.each do |two_three|

  if two_three.to_s.length == 1

    two_three = "0#{two_three}"

  end



  four_five = 78



  arr1 = (2..27).to_a

  arr2 = [0,1,5,6,13,14]

  arr3 = arr1-arr2

  arr3.each do |six_seven|

    if six_seven.to_s.length == 1

      six_seven = "0#{six_seven}"

    else 

      six_seven = "#{six_seven}"

    end



    Array.new(100000) do |index|

      index = index + 1



      if index.to_s.length == 1

        eight_twelve = "0000#{index}"

      elsif index.to_s.length == 2

        eight_twelve = "000#{index}"

      elsif index.to_s.length == 3

        eight_twelve = "00#{index}"

      elsif index.to_s.length == 4

        eight_twelve = "0#{index}"

      end



      file.puts "#{one}#{two_three}#{four_five}#{six_seven}#{eight_twelve}"

    end

  end

end

Its working, but incorrectly.
Results
And continues to jump throughout all results (return thirteen-digit only on at string number 200000).
Thanks for your help.

Array#product is the method of choice here.

First construct the following array.

arr = [['1'], [*'05'..'15'], ['78'], [*'02'..'04', *'07'..'12', *'15'..'27'],

       [*'00000'..'99999']]

  #=> [["1"], ["05", "06", "07", "08", "09", "10", "11", "12", "13", "14", "15"],

  #    ["78"], ["02", "03", "04", "07", "08", "09", "10", "11", "12", "15",

  #     "16", "17", "18", "19", "20", "21", "22", "23", "24", "25", "26", "27"],

  #     "00000", "00001",..., "99999"]

The sizes of each element (array) of arr is as follows.

arr.map(&:size)

  #=> [1, 11, 1, 22, 100000]

To generate all combinations of arrays obtained by selecting one element from each element (array) of arr and then converting the resultant array to a string we write the following (which takes awhile to execute):

combos = arr.first.product(*arr.drop(1)).map(&:join)

n = combos.size

  #=> 24200000



combos.first(2)

  #=> ["105780200000", "105780200001"]

combos.last(2)

  #=> ["115782799998", "115782799999"]

5.times do

  i = rand(n)

  puts "%5d -> %s" % [i, combos[i]]

end

 9379583 -> 109780979583

12310295 -> 110781910295

11619403 -> 110781019403

 3571703 -> 106781971703

18237011 -> 113781037011

Note:

size.reduce(:*)

  #=> 24200000