binary-trees Matz's Ruby #4 program

# The Computer Language Benchmarks Game
# https://salsa.debian.org/benchmarksgame-team/benchmarksgame/
#
# contributed by Jesse Millikan
# Modified by Wesley Moxam
# Modified by Scott Leggett
# *reset*

def item_check(left, right)
    if left
        1 + item_check(*left) + item_check(*right)
    else
        1
    end
end

def bottom_up_tree(depth)
    if depth > 0
        depth -= 1
        [bottom_up_tree(depth), bottom_up_tree(depth)]
    else
        [nil, nil]
    end
end

max_depth = ARGV[0].to_i
min_depth = 4

max_depth = [min_depth + 2, max_depth].max

stretch_depth = max_depth + 1
stretch_tree = bottom_up_tree(stretch_depth)

puts "stretch tree of depth #{stretch_depth}\t check: #{item_check(*stretch_tree)}"
stretch_tree = nil

long_lived_tree = bottom_up_tree(max_depth)

min_depth.step(max_depth, 2) do |depth|
  iterations = 2**(max_depth - depth + min_depth)

  check = 0

  (1..iterations).each do |i|
    check += item_check(*bottom_up_tree(depth))
  end

  puts "#{iterations}\t trees of depth #{depth}\t check: #{check}"
end

puts "long lived tree of depth #{max_depth}\t check: #{item_check(*long_lived_tree)}"
    

NOTES:
64-bit Ubuntu quad core
ruby 1.8.7 (2008-08-11 patchlevel 72) [x86_64-linux]
 
So old that I haven't been able to get rubygems to work
no backport, no gmp


Sun, 02 Jun 2019 05:15:34 GMT

COMMAND LINE:
/usr/bin/ruby binarytrees.mri-4.mri 21

PROGRAM OUTPUT:
stretch tree of depth 22	 check: 8388607
2097152	 trees of depth 4	 check: 65011712
524288	 trees of depth 6	 check: 66584576
131072	 trees of depth 8	 check: 66977792
32768	 trees of depth 10	 check: 67076096
8192	 trees of depth 12	 check: 67100672
2048	 trees of depth 14	 check: 67106816
512	 trees of depth 16	 check: 67108352
128	 trees of depth 18	 check: 67108736
32	 trees of depth 20	 check: 67108832
long lived tree of depth 21	 check: 4194303