0297-serialize-and-deserialize-binary-tree.go

type Codec struct {
}

func Constructor() Codec {
    return Codec{}
}

func (this *Codec) serialize(root *TreeNode) string {
    res := make([]string, 0)
    
    var dfs func(node* TreeNode)
    dfs = func(node *TreeNode) {
        if node == nil{
            res = append(res, "N")
            return
        }
        res = append(res, strconv.Itoa(node.Val))
        dfs(node.Left)
        dfs(node.Right)
    }
    
    dfs(root)
    return strings.Join(res, ",")
}

func (this *Codec) deserialize(data string) *TreeNode {    
    vals := strings.Split(data, ",")
    i := 0
    
    var dfs func() *TreeNode
    dfs = func() *TreeNode {
        if vals[i] == "N" {
            i += 1
            return nil
        }
        val, _ := strconv.Atoi(vals[i])
        node := &TreeNode{Val: val}
        i += 1
        node.Left = dfs()
        node.Right = dfs()
        return node
    }
    
    return dfs()
}