Кто-то, помогите мне исправить ошибку атрибута в python - PullRequest
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Кто-то, помогите мне исправить ошибку атрибута в python

0 голосов
/ 14 апреля 2020

, когда я пытаюсь отсортировать связанный список, используя сортировку слиянием, я получаю эту ошибку: AttributeError: 'NoneType' object has no attribute 'info' методы вызова: 

mList = SingleLinkedList()
mList.create_list()
mList.merge_sort()

сообщение об ошибке: 

PS C:\Users\Slimane\Desktop\helloworld> & C:/Users/Slimane/AppData/Local/Programs/Python/Python38/python.exe c:/Users/Slimane/Desktop/helloworld/Untitled-1.py
Enter the number of the nodes: 5
Enter the data: 4
Enter the data: 3
Enter the data: 9
Enter the data: 1
Enter the data: 7
Traceback (most recent call last):
  File "c:/Users/Slimane/Desktop/helloworld/Untitled-1.py", line 89, in <module>
    mList.merge_sort()
  File "c:/Users/Slimane/Desktop/helloworld/Untitled-1.py", line 73, in merge_sort
    self.start = self._merge_sort_rec(self.start)
  File "c:/Users/Slimane/Desktop/helloworld/Untitled-1.py", line 80, in _merge_sort_rec
    start1 = self._merge_sort_rec(start1)
  File "c:/Users/Slimane/Desktop/helloworld/Untitled-1.py", line 82, in _merge_sort_rec
    startM = self._merge1(start1, start2)
  File "c:/Users/Slimane/Desktop/helloworld/Untitled-1.py", line 39, in _merge1
    if p1.info<= p2.info:
AttributeError: 'NoneType' object has no attribute 'info'

мой код : 

class Node:
    def __init__(self, value):
        self.info = value
        self.link = None

class SingleLinkedList:

    def __init__(self):
        self.start = None

    def create_list(self):
        n = int(input("Enter the number of the nodes: "))
        for i in range(n):
            data = int(input("Enter the data: "))
            self.insert_at_end(data)

    def display_list(self):
        if self.start is None:
            print("The list is empty!")
        else:
            print("the list contains: ")
            p = self.start
            while p is not None:
                print(p.info, " ", end=" ")
                p = p.link
            print()

    def insert_at_end(self, data):
        temp = Node(data)
        if self.start is None:
            self.start = temp
        else:    
            p = self.start
            while p.link is not None:
                p = p.link
            p.link = temp

    def _merge1(self, p1, p2):
        if p1.info<= p2.info:
            startM = Node(p1.info)
            p1 = p1.link
        else:
            startM = Node(p2.info)
            p2 = p2.link
        pM = startM
        while p1 != None and p2 != None:
            if p1.info < p2.info:
                pM.link = Node(p1.info)
                p1 = p1.link
            else:
                pM.link = Node(p2.info)
                p2 = p2.link
            pM = pM.link
        else:
            while p1 != None:
                pM.link = Node(p1.info)
                p1 = p1.link
            while p2 != None:
                pM.link = Node(p2.info)
                p2 = p2.link
        return startM

    def _divide_list(self, p):
        q = p.link.link
        while q is not None and q.link is not None:
            p = p.link
            q = q.link.link
        start2 = p.link
        p.link = None # this important line of code cut the list in the last node we reach
        return start2        

    def merge_sort(self):
        self.start = self._merge_sort_rec(self.start)

    def _merge_sort_rec(self, listStart):
        if listStart.link is None and listStart is not None:
            return
        start1 = listStart
        start2 = self._divide_list(listStart)
        start1 = self._merge_sort_rec(start1)
        start2 = self._merge_sort_rec(start2)
        startM = self._merge1(start1, start2)
        return startM
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