code kata 230811

binary_tree_230809/main_test.go

@@ -92,6 +92,21 @@ func postOrder2(n *node) {
 	}
 }
 
+func levelOrder(n *node) {
+	q := MakeQueue()
+	q.EnQueue(n)
+	for !q.IsEmpty() {
+		p := q.DeQueue().(*node)
+		visit(p)
+		if p.left != nil {
+			q.EnQueue(p.left)
+		}
+		if p.right != nil {
+			q.EnQueue(p.right)
+		}
+	}
+}
+
 func TestPreOrder(t *testing.T) {
 	preOrder(makeBinary())
 }
@@ -116,6 +131,10 @@ func TestPostOrder2(t *testing.T) {
 	postOrder2(makeBinary())
 }
 
+func TestLevelOrder(t *testing.T) {
+	levelOrder(makeBinary())
+}
+
 func visit(n *node) {
 	if n == nil {
 		return

binary_tree_230809/queue.go

@@ -0,0 +1,28 @@
+package main
+
+type Queue []interface{}
+
+func MakeQueue() *Queue {
+	return &Queue{}
+}
+
+func (q Queue) Len() int {
+	return len(q)
+}
+
+func (q Queue) IsEmpty() bool {
+	return len(q) == 0
+}
+
+func (q *Queue) EnQueue(item interface{}) {
+	*q = append(append(*q, item))
+}
+
+func (q *Queue) DeQueue() interface{} {
+	if (*q).Len() == 0 {
+		return nil
+	}
+	item := (*q)[0]
+	*q = (*q)[1:len(*q)]
+	return item
+}