bm_so_binary_trees.rb

# The Computer Language Shootout Benchmarks
# http://shootout.alioth.debian.org
#
# contributed by Jesse Millikan

# disable output
def STDOUT.write_ *args
end

def item_check(tree)
 if tree[0] == nil
  tree[1]
 else
  tree[1] + item_check(tree[0]) - item_check(tree[2])
 end
end

def bottom_up_tree(item, depth)
 if depth > 0
  item_item = 2 * item
  depth -= 1
  [bottom_up_tree(item_item - 1, depth), item, bottom_up_tree(item_item, depth)]
 else
  [nil, item, nil]
 end
end

max_depth = 12 # 16 # ARGV[0].to_i
min_depth = 4

max_depth = min_depth + 2 if min_depth + 2 > max_depth

stretch_depth = max_depth + 1
stretch_tree = bottom_up_tree(0, stretch_depth)

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

long_lived_tree = bottom_up_tree(0, max_depth)

min_depth.step(max_depth + 1, 2) do |depth|
 iterations = 2**(max_depth - depth + min_depth)

 check = 0

 for i in 1..iterations
  temp_tree = bottom_up_tree(i, depth)
  check += item_check(temp_tree)

  temp_tree = bottom_up_tree(-i, depth)
  check += item_check(temp_tree)
 end

 puts "#{iterations * 2}\t trees of depth #{depth}\t check: #{check}"
end

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