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| package main
import "fmt"
// 定义
type Tree struct {
Val int
Left *Tree
Right *Tree
IsRoot bool
}
func NewTree() (*Tree) {
node8 := Tree{Val: 8}
node9 := Tree{Val: 9}
node7 := Tree{Val: 7}
node6 := Tree{Val: 6, Left: &node8, Right: &node9}
node5 := Tree{Val: 5}
node4 := Tree{Val: 4}
node3 := Tree{Val: 3, Left: &node6, Right: &node7}
node2 := Tree{Val: 2, Left: &node4, Right: &node5}
root := Tree{Val: 1, Left: &node2, Right: &node3, IsRoot: true}
return &root
}
// 递归生成一个二叉树
func NewTree2(t *Tree, depth int) {
if depth < 3 {
t.Left = &Tree{Val: 2 * depth}
t.Right = &Tree{Val: 4 * depth}
NewTree2(t.Left, depth+1)
NewTree2(t.Right, depth+1)
}
}
func main() {
root := NewTree()
//t := Tree{}
//NewTree2(&t, 1)
//
//root = &t
PreOrder(root)
fmt.Println()
MidOrder(root)
fmt.Println()
PostOrder(root)
fmt.Println()
LevelOrder(root)
fmt.Println()
LevelOrder2(root)
fmt.Println()
PreOrder2(root)
fmt.Println()
MinOrder2(root)
fmt.Println()
PostOrder2(root)
fmt.Println()
}
// 前序遍历
func PreOrder(t *Tree) {
if t == nil {
return
}
fmt.Print(t.Val, " ")
PreOrder(t.Left)
PreOrder(t.Right)
}
// 中序遍历
func MidOrder(t *Tree) {
if t == nil {
return
}
MidOrder(t.Left)
fmt.Print(t.Val, " ")
MidOrder(t.Right)
}
// 后续遍历
func PostOrder(t *Tree) {
if t == nil {
return
}
PostOrder(t.Left)
PostOrder(t.Right)
fmt.Print(t.Val, " ")
}
// 层序遍历
func LevelOrder(t *Tree) {
queue := []*Tree{t}
if t == nil {
return
}
// 注意此为2层循环
for len(queue) > 0 {
length := len(queue)
for length > 0 {
length--
if queue[0].Left != nil {
queue = append(queue, queue[0].Left)
}
if queue[0].Right != nil {
queue = append(queue, queue[0].Right)
}
fmt.Print(queue[0].Val, " ")
queue = queue[1:]
}
}
}
// 前序遍历
func PreOrder2(root *Tree) {
queue := make([]*Tree, 0)
for root != nil || len(queue) != 0 {
for root != nil {
fmt.Print(root.Val, " ")
queue = append(queue, root)
root = root.Left
}
root = queue[len(queue)-1].Right
queue = queue[:len(queue)-1]
}
}
// 中序遍历
func MinOrder2(root *Tree) {
queue := make([]*Tree, 0)
for root != nil || len(queue) != 0 {
for root != nil {
queue = append(queue, root)
root = root.Left
}
node := queue[len(queue)-1]
fmt.Print(node.Val, " ")
queue = queue[:len(queue)-1]
root = node.Right
}
}
// 后续遍历
func PostOrder2(root *Tree) {
queue := make([]*Tree, 0)
var lastVisited *Tree
for root != nil || len(queue) != 0 {
for root != nil {
queue = append(queue, root)
root = root.Left
}
n := queue[len(queue)-1]
if n.Right == nil || n.Right == lastVisited {
fmt.Print(n.Val, " ")
queue = queue[:len(queue)-1]
lastVisited = n
} else {
root = n.Right
}
}
}
type Queue struct {
Val []*Tree
len int
}
func (q *Queue) Push(t *Tree) {
q.Val = append(q.Val, t)
}
func (q *Queue) Pop() (node *Tree) {
len := q.len
if len == 0 {
fmt.Println("queue is empty")
}
node = q.Val[0]
if len == 1 {
q.Val = []*Tree{}
} else {
q.Val = q.Val[1:]
}
return
}
func (q *Queue) Len() int {
q.len = len(q.Val)
return q.len
}
// 层序遍历2
func LevelOrder2(t *Tree) {
q := Queue{}
q.Push(t)
for q.Len() > 0 {
node := q.Pop()
if node == nil {
panic("node is nil")
}
if node.IsRoot {
fmt.Print(node.Val, " ")
}
if node.Left != nil {
fmt.Print(node.Left.Val, " ")
q.Push(node.Left)
}
if node.Right != nil {
fmt.Print(node.Right.Val, " ")
q.Push(node.Right)
}
}
}
|
