Floyd's triangle   lists the natural numbers in a right triangle aligned to the left where

 the first row is   1     (unity)
 successive rows start towards the left with the next number followed by successive naturals listing one more number than the line above.


The first few lines of a Floyd triangle looks like this:

 1
 2  3
 4  5  6
 7  8  9 10
11 12 13 14 15



Task

 Write a program to generate and display here the first   n   lines of a Floyd triangle. 
(Use   n=5   and   n=14   rows).
 Ensure that when displayed in a mono-space font, the numbers line up in vertical columns as shown and that only one space separates numbers of the last row.


def floyd(rows)
  max = (rows * (rows + 1)) / 2
  widths = ((max - rows + 1)..max).map {|n| n.to_s.length + 1}
  n = 0
  rows.times do |r|
    puts (0..r).map {|i| n += 1; "%#{widths[i]}d" % n}.join
  end
end
 
floyd(5)
floyd(14)