Generate deck of cards with single link

spotit.rb

#!/usr/bin/env ruby

# use prime numbers
def generate_deck(size = 7)
  cards = []

  (0...size).each do |i|
    (0...size).each do |j|
      card = []
      (0...size).each do |k|
        h = ((i*k+j) % size) * size + k
        card << h
      end
      h = size * size + i
      card << h
      cards << card
    end
  end

  (0...size).each do |i|
    card = []
    (0...size).each do |j|
      h = j * size + i
      card << h
    end
    h = size * size + size
    card << h
    cards << card
  end

  card = []
  (0..size).each do |i|
    h = size * size + i
    card << h
  end
  cards << card

  cards
end

def validate(check_card, cards)
  cards.each do |card|
    next if check_card == card

    matches = 0
    check_card.each do |n|
      matches += 1 if card.include?(n)
    end

    raise("Card #{check_card.inspect} and #{card.inspect} with #{matches} matches") if matches != 1
  end
end

cards = generate_deck(7)

cards.each do |card|
  validate(card, cards)
end

cards.each do |card|
  puts(card.join(' '))
end