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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) } } }
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