Update go dependencies

vendor/github.com/petar/GoLLRB/llrb/llrb-stats.go

@@ -0,0 +1,46 @@
+// Copyright 2010 Petar Maymounkov. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package llrb
+
+// GetHeight() returns an item in the tree with key @key, and it's height in the tree
+func (t *LLRB) GetHeight(key Item) (result Item, depth int) {
+	return t.getHeight(t.root, key)
+}
+
+func (t *LLRB) getHeight(h *Node, item Item) (Item, int) {
+	if h == nil {
+		return nil, 0
+	}
+	if less(item, h.Item) {
+		result, depth := t.getHeight(h.Left, item)
+		return result, depth + 1
+	}
+	if less(h.Item, item) {
+		result, depth := t.getHeight(h.Right, item)
+		return result, depth + 1
+	}
+	return h.Item, 0
+}
+
+// HeightStats() returns the average and standard deviation of the height
+// of elements in the tree
+func (t *LLRB) HeightStats() (avg, stddev float64) {
+	av := &avgVar{}
+	heightStats(t.root, 0, av)
+	return av.GetAvg(), av.GetStdDev()
+}
+
+func heightStats(h *Node, d int, av *avgVar) {
+	if h == nil {
+		return
+	}
+	av.Add(float64(d))
+	if h.Left != nil {
+		heightStats(h.Left, d+1, av)
+	}
+	if h.Right != nil {
+		heightStats(h.Right, d+1, av)
+	}
+}