链表题：如何检测链表中是否有环？如何删除链表中等于某个值的所有节点？
如何检测链表中是否有环？
public class ListNode {
public var val: Int
public var next: ListNode?
public init(_ val: Int) {
self.val = val
self.next = nil
}
}
extension ListNode {
var hasCycle: Bool {
var slow:ListNode? = self
var fast = self.next
while fast != nil {
if slow! === fast! {
return true
}
slow = slow?.next
fast = fast?.next?.next
}
return false
}
}
如何删除链表中等于某个值的所有节点？
func remove(with value:Int, from listNode:ListNode?) -> ListNode? {
let tmpNode = ListNode(0)
tmpNode.next = listNode
var currentNode = tmpNode.next
var persiousNode:ListNode? = tmpNode
while currentNode != nil {
if let nodeValue = currentNode?.val, nodeValue == value {
persiousNode?.next = currentNode?.next
}else {
persiousNode = currentNode
}
currentNode = currentNode?.next
}
return tmpNode.next
}
