Golang二叉树搜索算法翻译

Question

I'm beginner to Golang and trying to build a Binary Search Tree. My source code to do it:

package main

import (
    "fmt"
    "math/rand"
    "time"
)

type Node struct{
    value int
    left *Node
    right *Node
}

func insert(root *Node,v int){
    if root==nil{
        root=&Node{v,nil,nil}
    } else if v<root.value{
        insert(root.left,v)
    } else{
        insert(root.right,v)
    }
}

func inTraverse(root *Node){
    if (root==nil){
        return
    }
    inTraverse(root.left)
    fmt.Printf("%d",root.value)
    inTraverse(root.right)
}

func main() {
    var treeRoot *Node
    rand.Seed(time.Now().UnixNano())
    n:=6
    var a[6]int
    for i:=0;i<n;i++{
        a[i]=rand.Intn(20)+1
    }
    fmt.Println("Array of integer: ")
    for i:=0;i<n;i++{
        fmt.Printf("%d ",a[i])
    }
    fmt.Println()
    for i:=0;i<n;i++{
        insert(treeRoot,a[i])
    }
    inTraverse(treeRoot)
    fmt.Println()
}

The result shows an empty tree. What's wrong with my code? Does Golang have pass-by-value or pass-by-reference? Please help me solve this.

Answer 1

Go always passes parameters by value. You should rather write:

func insert(root *Node,v int) *Node {
    if root == nil{
        root = &Node{v,nil,nil}
    } else if v<root.value{
        root.left = insert(root.left,v)
    } else{
        root.right = insert(root.right,v)
    }
    return root
}

and:

for i:=0;i<n;i++{
    treeRoot = insert(treeRoot,a[i])
}

See the result at: http://play.golang.org/p/94H_l3rfSH