数据结构——两个有序链表序列的合并（Swift）

在学习的时候作业只能用c语言，写完提交后用swift重新写一遍，实现结构不太相同。

import Foundation

class ListNode{
    var data: Int
    var next: ListNode?
    
    init(_ data: Int) {
        self.data = data
        self.next = nil
    }
}

class List {
    var head: ListNode?
    var tail: ListNode?
    
    func appendToTail(_ data: Int){
        if tail == nil {
            tail = ListNode(data)
            head = tail
        }else{
            tail!.next = ListNode(data)
            tail = tail!.next
        }
    }
    
    func AppendTail(Node: ListNode){
        if tail == nil{
            tail = Node
            head = tail
        }else{
            tail!.next = Node
            tail = tail!.next
        }
    }
    
    func appendToHead(_ data: Int){
        if head == nil{
            head = ListNode(data)
            tail = head
        }else{
            let temp = ListNode(data)
            temp.next = head
            head = temp
        }
    }
    
    func printList(){
        if head == nil{
            print("NULL")
        }else{
            var temp = head
            while(temp != nil){
                print(temp!.data,terminator: " ")
                temp = temp!.next;
            }
        }
    }
    
    func merge(withList L2: List) -> List{
        var L = List.init()
        var Node1 = head
        var Node2 = L2.head
        var t1: Int
        var t2: Int
        while (Node1 != nil && Node2 != nil){
            t1 = Node1!.data
            t2 = Node2!.data
            if t1 <= t2{
                L.AppendTail(Node: Node1!)
                Node1 = Node1!.next
            }else{
                L.AppendTail(Node: Node2!)
                Node2 = Node2!.next
            }
        }
        Node1 != nil ? (L.AppendTail(Node: Node1!)) : (L.AppendTail(Node: Node2!))
        return L
    }
    
    init() {
        head = nil
        tail = nil
    }
}

func Read() ->List {
    let L = List.init()
    let r1 = Int(readLine()!)!
    
    if r1 != 0 {
        let intput = readLine()!.components(separatedBy: NSMutableCharacterSet.whitespaces)
        let datas = intput.map {Int($0)!}
        for i in 0...(r1-1){
            L.appendToTail(datas[i])
        }
    }else{
        exit(0)
    }
   return L
}


let L = Read()
let L2 = Read()
let L3 = L.merge(withList: L2)
L3.printList()

　　以上。