我正在尝试在Swift平台上实现队列集合类型。关于peek、poll和offer函数,我遇到了一些问题。当我在我的代码中尝试使用这些函数时会失败。您有任何建议或真正的算法吗?
import Foundation
class Node<T> {
var value: T? = nil
var next: Node<T>? = nil
var prev: Node<T>? = nil
init() {
}
init(value: T) {
self.value = value
}
}
class Queue<T> {
var count: Int = 0
var head: Node<T> = Node<T>()
var tail: Node<T> = Node<T>()
var currentNode : Node<T> = Node<T>()
init() {
}
func isEmpty() -> Bool {
return self.count == 0
}
func next(index:Int) -> T? {
if isEmpty() {
return nil
} else if self.count == 1 {
var temp: Node<T> = currentNode
return temp.value
} else if index == self.count{
return currentNode.value
}else {
var temp: Node<T> = currentNode
currentNode = currentNode.next!
return temp.value
}
}
func setCurrentNode(){
currentNode = head
}
func enQueue(key: T) {
var node = Node<T>(value: key)
if self.isEmpty() {
self.head = node
self.tail = node
} else {
node.next = self.head
self.head.prev = node
self.head = node
}
self.count++
}
func deQueue() -> T? {
if self.isEmpty() {
return nil
} else if self.count == 1 {
var temp: Node<T> = self.tail
self.count--
return temp.value
} else {
var temp: Node<T> = self.tail
self.tail = self.tail.prev!
self.count--
return temp.value
}
}
//retrieve the top most item
func peek() -> T? {
if isEmpty() {
return nil
}
return head.value!
}
func poll() -> T? {
if isEmpty() {
return nil
}else{
var temp:T = head.value!
deQueue()
return temp
}
}
func offer(var key:T)->Bool{
var status:Bool = false;
self.enQueue(key)
status = true
return status
}
}