Python - Delete all nodes of the Doubly Linked List
Deleting all nodes of a doubly linked list requires traverse through the list and deleting each node one by one. It requires creating a temp node pointing to the head then move the head to head next. After that delete the temp node. Repeat the process till the head becomes null.
The function deleteAllNodes is created for this purpose. It is a 2-step process.
def deleteAllNodes(self): #1 & 2. create a temp node, if the head is not # null make temp as head and move head to head # next, then delete the temp, continue the # process till head becomes null while (self.head != None): temp = self.head self.head = self.head.next temp = None print("All nodes are deleted successfully.")
The below is a complete program that uses above discussed concept of deleting all nodes of a 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 return else: temp = self.head while(temp.next != None): temp = temp.next temp.next = newNode newNode.prev = temp #delete all nodes of the list def deleteAllNodes(self): while (self.head != None): temp = self.head self.head = self.head.next temp = None print("All nodes are deleted successfully.") #display the content of the list def PrintList(self): temp = self.head if(temp != None): print("The list contains:", end=" ") while (temp != None): print(temp.data, end=" ") temp = temp.next print() else: print("The 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.