gistfile1.txt

abstract BTree
type Empty <: BTree
end
type Node <: BTree
    info::Int
    left::BTree
    right::BTree
end
const min_depth = 4

function make(val, d)
    if d > 0 
        Node(val, make(2*val-1, d-1), make(2*val, d-1))
    else 
        Node(val, Empty(), Empty())
    end
end
check(t::Empty) = 0
check(t::Node) = t.info + check(t.left) - check(t.right)
function binary_trees(N::Int=10)
    max_depth = N
    stretch_depth = max_depth + 1
    c = check(make(0, stretch_depth))
    long_lived_tree = make(0, max_depth)
    d = min_depth
    for i = 0:div(max_depth - d, 2)
        niter = 1 << (max_depth - d + min_depth)
        c = 0
        for j = 1:niter
            c += check(make(i, d)) + check(make(-i, d))
        end
        d += 2        
    end
end