Tree Operations in Golang

Tree operations [Insertion, Inorder, Postorder, Level order] Explained

package main
import (
 "fmt"
)
type Node struct {
 Val   int
 Left  *Node
 Right *Node
}
func NewNode(val int) *Node {
 node := &Node{Val: val}
 return node
}
func AddNode(head *Node, val int) *Node {
 if head == nil {
  return NewNode(val)
 }
 tmp := head
 for tmp != nil {
  if val < tmp.Val {
   if tmp.Left == nil {
    tmp.Left = NewNode(val)
    return head
   } else {
    tmp = tmp.Left
   }
  } else {
   if tmp.Right == nil {
    tmp.Right = NewNode(val)
    return head
   } else {
    tmp = tmp.Right
   }
  }
 }
 return head
}
func CreateTree() (head *Node) {
 head = AddNode(head, 50)
 head = AddNode(head, 30)
 head = AddNode(head, 70)
 head = AddNode(head, 20)
 head = AddNode(head, 40)
 head = AddNode(head, 60)
 head = AddNode(head, 80)
 return head
}
func inorder(head *Node) {
 if head == nil {
  return
 }
 inorder(head.Left)
 fmt.Print(head.Val, " ")
 inorder(head.Right)
}
func postorder(head *Node) {
 if head == nil {
  return
 }
 postorder(head.Left)
 postorder(head.Right)
 fmt.Print(head.Val, " ")
}
func levelOrder(head *Node) {
q := make([]*Node, 0)
 q = append(q, head)
for len(q) > 0 {
  front := q[0]
  fmt.Print(front.Val, " ")
  if front.Left != nil {
   q = append(q, front.Left)
  }
  if front.Right != nil {
   q = append(q, front.Right)
  }
  q = q[1:]
 }
}
func main() {
 head := CreateTree()
 fmt.Println("Inorder : ")
 inorder(head)
 fmt.Println("\nPostorder : ")
 postorder(head)
 fmt.Println("\nLevel Order : ")
 levelOrder(head)
}