Reconstruction of a Tree

package main

import (
    "fmt"
    "strings"
)

func scanInput() (n int, pre []int, in []int) {
    fmt.Scanf("%d", &n)
    pre = make([]int, n)
    in = make([]int, n)
    for i := 0; i < n; i++ {
        fmt.Scanf("%d", &pre[i])
    }
    for i := 0; i < n; i++ {
        fmt.Scanf("%d", &in[i])
    }
    return
}

func printSlice(slice []int) {
    fmt.Println(strings.Trim(strings.Join(strings.Fields(fmt.Sprint(slice)), " "), "[]"))
}

func main() {
    n, pre, in := scanInput()
    post := make([]int, 0, n)
    parent := 0

    walk(0, len(pre)-1, &parent, pre, in, &post)

    printSlice(post)
}

func walk(left, right int, parent *int, pre, in []int, post *[]int) {
    if left > right {
        return
    }

    dlm := pre[*parent]
    *parent++

    var idx int
    for i, v := range in {
        if v == dlm {
            idx = i
            break
        }
    }

    walk(left, idx-1, parent, pre, in, post)
    walk(idx+1, right, parent, pre, in, post)

    *post = append(*post, dlm)
}