Python - Delete all nodes of the Circular Doubly Linked List
Deleting all nodes of a circular doubly linked list requires traverse through the list and deleting each node one by one. It requires creating a current node pointing to the next of head. Delete the current node and move to the next node using temp node. Repeat the process till the current node becomes head. At last, delete the head.
The function deleteAllNodes is created for this purpose. It is a 3-step process.
def deleteAllNodes(self): if self.head != None: #1. if head is not null create a temp node # and current node pointed to next of head current = self.head.next while(current != self.head): #2. if current node is not equal to head, delete the # current node and move current to next node using temp, # repeat the process till the current reaches the head temp = current.next current = None current = temp #3. Delete the head self.head = None print("\nAll nodes are deleted successfully.")
The below is a complete program that uses above discussed concept of deleting all nodes of a circular doubly linked list which makes the list empty with size zero.
# node structure class Node: def __init__(self, data): self.data = data self.next = None self.prev = None #class Linked List class LinkedList: def __init__(self): self.head = None #Add new element at the end of the list def push_back(self, newElement): newNode = Node(newElement) if(self.head == None): self.head = newNode newNode.next = self.head newNode.prev = self.head return else: temp = self.head while(temp.next != self.head): temp = temp.next temp.next = newNode newNode.next = self.head newNode.prev = temp self.head.prev = newNode #delete all nodes of the list def deleteAllNodes(self): if self.head != None: current = self.head.next while(current != self.head): temp = current.next current = None current = temp self.head = None print("\nAll nodes are deleted successfully.") #display the content of the list def PrintList(self): temp = self.head if(temp != None): print("\nThe list contains:", end=" ") while (True): print(temp.data, end=" ") temp = temp.next if(temp == self.head): break else: print("\nThe list is empty.") # test the code MyList = LinkedList() #Add four elements in the list. MyList.push_back(10) MyList.push_back(20) MyList.push_back(30) MyList.push_back(40) #Display the content of the list. MyList.PrintList() #delete all nodes of the list MyList.deleteAllNodes() #Display the content of the list. MyList.PrintList()
The above code will give the following output:
The list contains: 10 20 30 40 All nodes are deleted successfully. The list is empty.