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Python program to rotate doubly linked list by N nodes
When it is required to rotate a doubly linked list by a specific number of nodes, a ‘Node’ class needs to be created. In this class, there are three attributes, the data that is present in the node, the access to the next node of the linked list, and the access to the previous node of the linked list.
Below is a demonstration for the same −
Example
class Node:
def __init__(self, my_data):
self.previous = None
self.data = my_data
self.next = None
class double_list:
def __init__(self):
self.head = None
self.tail = None
self.size = 0
def add_data(self, my_data):
new_node = Node(my_data)
if(self.head == None):
self.head = self.tail = new_node
self.head.previous = None
self.tail.next = None
else:
self.tail.next = new_node
new_node.previous = self.tail
self.tail = new_node
self.tail.next = None
self.size = self.size + 1;
def print_it(self):
curr = self.head
if (self.head == None):
print("The list is empty")
return
print("The nodes in the doubly linked list are :")
while curr != None:
print(curr.data)
curr = curr.next
def rotate_list(self, num):
curr = self.head;
if(num == 0 or num >= self.size):
return;
else:
for i in range(1, num):
curr = curr.next;
self.tail.next = self.head;
self.head = curr.next;
self.head.previous = None;
self.tail = curr;
self.tail.next = None;
my_instance = double_list()
print("Elements are being added to the doubly linked list")
my_instance.add_data(10)
my_instance.add_data(24)
my_instance.add_data(54)
my_instance.add_data(77)
my_instance.add_data(24)
my_instance.add_data(0)
my_instance.print_it()
print("The elements in the list after rotating : ")
my_instance.rotate_list(4)
my_instance.print_it()Output
Elements are being added to the doubly linked list The nodes in the doubly linked list are : 10 24 54 77 24 0 The elements in the list after rotating : The nodes in the doubly linked list are : 24 0 10 24 54 77
Explanation
- The ‘Node’ class is created.
- Another class with required attributes is created.
- Another method named ‘add_data’ is defined, that is used to add data to the circular linked list.
- Another method named ‘rotate_list’ is defined, that uses the specific node as pivot and rotates the list, thereby moving the elements to a different position.
- Another method named ‘print_it’ is defined that is used to display the linked list data on the console.
- An object of the ‘double_list’ class is created, and the methods are called on it to add data.
- The ‘rotate_list’ method is called.
- It iterates through the nodes in the linked list, gets the middle most index and starts deleting the elements.
- This is displayed on the console using the ‘print_it’ method.
Updated on: 11-Mar-2021
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