gistfile1.rb

def f(ra,n)
  r=0
  ra.each {|x| r+=1 if x.include? n}
  r
end

def g(ra, n)
  ra.inject(0){|m, x| m + (x.include?(n) ? 1 : 0) }
end

a = [[1,2], [2,3], [3,4], [1,4]]
puts "#{f(a, 1)} = #{g(a, 1)}"
puts "#{f(a, 2)} = #{g(a, 2)}"
puts "#{f(a, 3)} = #{g(a, 3)}"
puts "#{f(a, 4)} = #{g(a, 4)}"
puts "#{f(a, 5)} = #{g(a, 5)}"