Question

我目前正在实现的python中有一个链表。但是，删除第一个节点的情况不适用于我。

删除列表中其他任何位置的节点都可以。

我搜索了youtube教程和其他在线帖子，但似乎有与我完全相同的代码行。

我还尝试过将打印语句放在各行之前 -self.head = HeadVal.nextval -HeadVal =无

从输出中看，它似乎确实将根节点传递到了列表的第二个元素上，并清除了原始的第一项，但是当我再次打印列表时，原始的第一个节点尚未被删除。它是否就像新的列表结构尚未提交到内存那样？

类节点： def init（self，dataval）： self.dataval =数据值 self.nextval =无

LinkedList类： def init（self）： self.headval =无

def listprint(self):

    printval = self.headval

    while printval is not None:
        print (printval.dataval)
        printval = printval.nextval

def insertAtBegining(self):

    nodeToPutAtStart = input("Enter Node To Put At The Start: ")

    startNode = Node()
    startNode.init(nodeToPutAtStart)


    startNode.nextval = self.headval
    self.headval = startNode

    print(nodeToPutAtStart, " Has Been Added To The Start Of The Linked List")       

def insertAtEnd(self):

    nodeToPutOnEnd = input("Enter Node To Put On The End: ")

    endNode = Node()
    endNode.init(nodeToPutOnEnd)

    if self.headval is None:
        self.headval = endNode
        return

    laste = self.headval

    while(laste.nextval):
        laste = laste.nextval

    laste.nextval=endNode

    print(nodeToPutOnEnd, " Has Been Added To The End Of The Linked List")




def removeNode(self):

    nodeToRemove = input("Enter Node To Remove: ")
    HeadVal = self.headval

    if (HeadVal is not None):
        if (HeadVal.dataval == nodeToRemove):
            self.head = HeadVal.nextval
            HeadVal = None
            return
        else:
            print("B")
            while (HeadVal is not None):
               if HeadVal.dataval == nodeToRemove:
                    break
               prev = HeadVal
               HeadVal = HeadVal.nextval

            prev.nextval = HeadVal.nextval
            HeadVal = None
    else:
        print("Nothing To Delete")

def MainMenu（）：

print("1. Create A Linked List")
print("2. Delete A Linked List")
print("3. Check If A Linked List Is Empty")
print("4. Print Out The Values In The List")
print("5. Find A Node In A Linked List")
print("6. Insert A Node In A Linked List")
print("7. Delete A Node In A Linked List")
print("99. Exit")

anotherOption = True

while anotherOption == True:

    print("")
    selection=int(input("Main Menu --- Enter Choice: "))

    if selection==1:    
        myList = LinkedList()
        myList.init()
        print("Linked List Created")

    elif selection==6:
        print("")
        print("A. Insert A Node Into The Front Of The Linked List")
        print("B. Insert A Node Into The End Of The Linked List")       
        print("")
        entrySelection=input("Enter Insert Node Choice: ")

        if entrySelection in ["A", "a"]:
            myList.insertAtBegining()
        elif entrySelection in ["B", "b"]:
            myList.insertAtEnd()

        else:
            print("")
            print("Enter A Valid Selection For Inserting Node")



    elif selection==4:
        myList.listprint()


    elif selection==7:
        myList.removeNode()

    elif selection==99:
        anotherOption = False
        print("")
        print("Exiting Main Menu")

    else:
        print("")
        print("Enter A Valid Selection On Main Menu")

MainMenu（）

从Python链接列表中删除第一个节点

0 个答案: