# Copyright © 2004-2013 Brent Fulgham
#
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# The Computer Language Benchmarks Game
# http://benchmarksgame.alioth.debian.org
#
# contributed by Jesse Millikan
# Modified by Wesley Moxam

# http://benchmarksgame.alioth.debian.org/u64q/program.php?test=binarytrees&lang=yarv&id=1

def item_check(left, item, right)
  return item if left.nil?
  item + item_check(*left) - item_check(*right)
end

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

def binary_trees(max_depth)
  sum = 0

  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)

  sum += 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

    sum += depth
    sum += check
  end

  sum += item_check(*long_lived_tree)

  sum
end

def harness_input
  15
end

def harness_sample(input)
  binary_trees(input)
end

def harness_verify(output)
  output == -87308
end

require 'bench9000/harness'