From 11674afa4167dc4c0d9dea9a974ddac4c43ff93b Mon Sep 17 00:00:00 2001
From: Kristoffer Carlsson <kcarlsson89@gmail.com>
Date: Wed, 9 Jan 2019 17:31:03 +0100
Subject: [PATCH] add back union in binarytrees

---
 binarytrees/binarytrees-union.jl | 58 ++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100644 binarytrees/binarytrees-union.jl

diff --git a/binarytrees/binarytrees-union.jl b/binarytrees/binarytrees-union.jl
new file mode 100644
index 0000000..3661cb7
--- /dev/null
+++ b/binarytrees/binarytrees-union.jl
@@ -0,0 +1,58 @@
+# The Computer Language Benchmarks Game
+# https://salsa.debian.org/benchmarksgame-team/benchmarksgame/
+
+# contributed by Jarret Revels and Alex Arslan
+# based on an OCaml program
+# *reset*
+
+using Printf
+
+abstract type BTree end
+
+mutable struct Node <: BTree
+    left::Union{Nothing, Node}
+    right::Union{Nothing, Node}
+end
+
+function make(d)
+    if d == 0
+        Node(nothing, nothing)
+    else
+        Node(make(d-1), make(d-1))
+    end
+end
+
+check(t::Nothing) = 0
+check(t::Node) = 1 + check(t.left) + check(t.right)
+
+function loop_depths(d, min_depth, max_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(d))
+        end
+        @printf("%i\t trees of depth %i\t check: %i\n", niter, d, c)
+        d += 2
+    end
+end
+
+function perf_binary_trees(N::Int=10)
+    min_depth = 4
+    max_depth = N
+    stretch_depth = max_depth + 1
+
+    # create and check stretch tree
+    let c = check(make(stretch_depth))
+        @printf("stretch tree of depth %i\t check: %i\n", stretch_depth, c)
+    end
+
+    long_lived_tree = make(max_depth)
+
+    loop_depths(min_depth, min_depth, max_depth)
+    @printf("long lived tree of depth %i\t check: %i\n", max_depth, check(long_lived_tree))
+
+end
+
+n = parse(Int,ARGS[1])
+perf_binary_trees(n)