golang数据结构之树的三种遍历方式

tree.go

package tree

import (
    "fmt"
)

type TreeNode struct {
    ID    int
    Val   int
    Left  *TreeNode
    Right *TreeNode
}

func PreOrder(root *TreeNode) {
    if root != nil {
        fmt.Printf("%d ", root.Val)
        PreOrder(root.Left)
        PreOrder(root.Right)
    }
}

func InOrder(root *TreeNode) {
    if root != nil {
        InOrder(root.Left)
        fmt.Printf("%d ", root.Val)
        InOrder(root.Right)
    }
}

func PostOrder(root *TreeNode) {
    if root != nil {
        PostOrder(root.Left)
        PostOrder(root.Right)
        fmt.Printf("%d ", root.Val)
    }
}

main.go

package main

import (
    "fmt"
    "go_code/data_structure/tree"
)

func main() {

    node7 := &tree.TreeNode{
        ID:    7,
        Val:   7,
        Left:  nil,
        Right: nil,
    }
    node6 := &tree.TreeNode{
        ID:    6,
        Val:   6,
        Left:  nil,
        Right: nil,
    }
    node5 := &tree.TreeNode{
        ID:    5,
        Val:   5,
        Left:  nil,
        Right: nil,
    }
    node4 := &tree.TreeNode{
        ID:    4,
        Val:   4,
        Left:  nil,
        Right: nil,
    }
    node3 := &tree.TreeNode{
        ID:    3,
        Val:   3,
        Left:  node6,
        Right: node7,
    }
    node2 := &tree.TreeNode{
        ID:    2,
        Val:   2,
        Left:  node4,
        Right: node5,
    }

    node1 := &tree.TreeNode{
        ID:    1,
        Val:   1,
        Left:  node2,
        Right: node3,
    }

    fmt.Println("先序遍历")
    tree.PreOrder(node1)
    fmt.Println()
    fmt.Println("中序遍历")
    tree.InOrder(node1)
    fmt.Println()
    fmt.Println("后序遍历")
    tree.PostOrder(node1)
}

运行结果：