Question

I’m new to Ruby. After a ton of refactoring I came down to this. Is there a better way to write this?

 51   def tri_num?(n)
 52     i = 1
 53     while i < n
 54       return i if i * (i + 1) / 2 == n
 55       i += 1
 56     end 
 57     raise InvalidTree
 58   end

Answer 1

What about solving it directly?

def tri_num? n

  i = (0.5*(-1.0 + Math.sqrt(1.0 + 8.0*n))).to_i

  if i*(i+1)/2 == n
    return i
  else
    raise InvalidTree
  end

end

Though I don’t know if tri_num? is a good name. Usually a function ending with a ? should return true or false.