4
Xcode抱怨說:「無法指定類型節點的值來鍵入節點< _>?」在第23,24,26,27行(在排隊的條件部分中'節點'到'頂部'和'底部'的分配)。我不知道這意味着什麼,以及爲什麼Xcode中看到了該類型的節點和頂/差異底部無法將節點類型爲<T>的值分配給類型節點<_>?
class Node<T> {
var key: T?
weak var next: Node<T>?
weak var previous: Node<T>?
init(key: T, previous: Node? = nil) {
self.key = key
self.previous = previous
}
}
class Dequeue<T> {
private var count: Int = 0
private weak var top: Node<T>?
private weak var bottom: Node<T>?
func enqueue<T>(val: T) {
// if dequeue is empty
let node = Node<T>(key: val)
if top == nil {
self.top = node
self.bottom = node
} else {
self.bottom?.next = node
self.bottom = node
}
}
}