From 06bd407a0c14cfb07b76afa1abeb98854ffffc0e Mon Sep 17 00:00:00 2001
From: dudaodong <lanliddd.2007@163.com>
Date: Tue, 1 Mar 2022 11:23:33 +0800
Subject: [PATCH] feat: add LevelOrderTraverse func

---
 datastructure/tree/bstree.go        |  7 +++++++
 datastructure/tree/bstree_test.go   | 18 ++++++++++++++++++
 datastructure/tree/tree_internal.go | 23 ++++++++++++++++++++++-
 3 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/datastructure/tree/bstree.go b/datastructure/tree/bstree.go
index d0090e4..a2441d8 100644
--- a/datastructure/tree/bstree.go
+++ b/datastructure/tree/bstree.go
@@ -63,6 +63,13 @@ func (t *BSTree[T]) InOrderTraverse() []T {
 	return inOrderTraverse(t.root)
 }
 
+// LevelOrderTraverse traverse tree node in level order
+func (t *BSTree[T]) LevelOrderTraverse() []T {
+	traversal := make([]T, 0)
+	levelOrderTraverse(t.root, &traversal)
+	return traversal
+}
+
 // Depth returns the calculated depth of a binary saerch tree
 func (t *BSTree[T]) Depth() int {
 	return calculateDepth(t.root, 0)
diff --git a/datastructure/tree/bstree_test.go b/datastructure/tree/bstree_test.go
index ceaddf4..fc54399 100644
--- a/datastructure/tree/bstree_test.go
+++ b/datastructure/tree/bstree_test.go
@@ -80,6 +80,24 @@ func TestBSTree_InOrderTraverse(t *testing.T) {
 	assert.Equal([]int{2, 4, 5, 6, 7}, acturl)
 }
 
+func TestBSTree_LevelOrderTraverse(t *testing.T) {
+	assert := internal.NewAssert(t, "TestBSTree_LevelOrderTraverse")
+
+	bstree := NewBSTree(6)
+
+	comparator := &intComparator{}
+	bstree.InsertNode(7, comparator)
+	bstree.InsertNode(5, comparator)
+	bstree.InsertNode(2, comparator)
+	bstree.InsertNode(4, comparator)
+
+	bstree.Print()
+
+	acturl := bstree.LevelOrderTraverse()
+	t.Log(acturl)
+	assert.Equal([]int{6, 5, 7, 2, 4}, acturl)
+}
+
 func TestBSTree_DeletetNode(t *testing.T) {
 	assert := internal.NewAssert(t, "TestBSTree_DeletetNode")
 
diff --git a/datastructure/tree/tree_internal.go b/datastructure/tree/tree_internal.go
index dbc4841..d701384 100644
--- a/datastructure/tree/tree_internal.go
+++ b/datastructure/tree/tree_internal.go
@@ -68,6 +68,24 @@ func inOrderPrint[T any](node *datastructure.TreeNode[T]) {
 	inOrderPrint(node.Right)
 }
 
+func levelOrderTraverse[T any](root *datastructure.TreeNode[T], traversal *[]T) {
+	var q []*datastructure.TreeNode[T] // queue
+	var n *datastructure.TreeNode[T]   // temp node
+
+	q = append(q, root)
+
+	for len(q) != 0 {
+		n, q = q[0], q[1:]
+		*traversal = append(*traversal, n.Data)
+		if n.Left != nil {
+			q = append(q, n.Left)
+		}
+		if n.Right != nil {
+			q = append(q, n.Right)
+		}
+	}
+}
+
 func insertTreeNode[T any](rootNode, newNode *datastructure.TreeNode[T], comparator lancetconstraints.Comparator) {
 	if comparator.Compare(newNode.Data, rootNode.Data) == -1 {
 		if rootNode.Left == nil {
@@ -199,5 +217,8 @@ func calculateDepth[T any](node *datastructure.TreeNode[T], depth int) int {
 }
 
 func max(a, b int) int {
-	return int(math.Max(float64(a), float64(b)))
+	if a > b {
+		return a
+	}
+	return b
 }