This is a Python program to interchange two adjacent nodes of a circular linked list.

The program creates a circular single linked list and allows the user to interchange two adjacent nodes in the list.

1. Create a class Node with instance variables data and next.

2. Create a class CircularLinkedList with instance variable head.

3. The variable head points to the first element in the circular single linked list.

4. Define methods get_node, get_prev_node, insert_after, insert_before, insert_at_end, append and display.

5. The method get_node takes an index as argument and traverses the list from the first node that many times to return the node at that index. It stops if it reaches the first node again.

6. The method get_prev_node takes a reference node as argument and returns the previous node.

7. The methods insert_after and insert_before insert a node after or before some reference node in the list.

8. The method insert_at_end inserts a node at the last position of the list.

9. The method display traverses the list from the first node and prints the data of each node. It stops when it reaches the first node again.

10. The method appends a node with the data item passed to the end of the list.

11. Define the function interchange which takes a linked list as argument and an index n.

12. The function interchange exchanges the nodes at indices n and n + 1 of the list.

13. Create an instance of CircularLinkedList, append data to it and perform the exchange operation.

Here is the source code of a Python program to interchange two adjacent nodes of a circular linked list. The program output is shown below.

class Node: def __init__(self, data): self.data = data self.next = None class CircularLinkedList: def __init__(self): self.head = None def get_node(self, index): if self.head is None: return None current = self.head for i in range(index): current = current.next if current == self.head: return None return current def get_prev_node(self, ref_node): if self.head is None: return None current = self.head while current.next != ref_node: current = current.next return current def insert_after(self, ref_node, new_node): new_node.next = ref_node.next ref_node.next = new_node def insert_before(self, ref_node, new_node): prev_node = self.get_prev_node(ref_node) self.insert_after(prev_node, new_node) def insert_at_end(self, new_node): if self.head is None: self.head = new_node new_node.next = new_node else: self.insert_before(self.head, new_node) def append(self, data): self.insert_at_end(Node(data)) def display(self): if self.head is None: return current = self.head while True: print(current.data, end = ' ') current = current.next if current == self.head: break def interchange(llist, n): current = llist.get_node(n) current2 = current.next if current2.next != current: before = llist.get_prev_node(current) after = current2.next before.next = current2 current2.next = current current.next = after if llist.head == current: llist.head = current2 elif llist.head == current2: llist.head = current a_cllist = CircularLinkedList() data_list = input('Please enter the elements in the linked list: ').split() for data in data_list: a_cllist.append(int(data)) n = int(input('The nodes at indices n and n+1 will be interchanged.' ' Please enter n: ')) interchange(a_cllist, n) print('The new list: ') a_cllist.display()

1. An instance of CircularLinkedList is created.

2. The user is prompted to enter the data items for the list.

3. The user is asked to enter n, the index of the node which will be interchanged with the node following it.

4. The function interchange is called to perform the exchange operation.

5. The linked list is displayed.

Case 1: Please enter the elements in the linked list: 1 2 The nodes at indices n and n+1 will be interchanged. Please enter n: 0 The new list: 2 1 Case 2: Please enter the elements in the linked list: 4 1 5 The nodes at indices n and n+1 will be interchanged. Please enter n: 2 The new list: 5 1 4 Case 3: Please enter the elements in the linked list: 3 18 40 1 6 The nodes at indices n and n+1 will be interchanged. Please enter n: 3 The new list: 3 18 40 6 1

**Sanfoundry Global Education & Learning Series – Python Programs.**

To practice all Python programs, __here is complete set of 150+ Python Problems and Solutions__.

**Related Posts:**

- Check Information Technology Books
- Apply for Programming Internship
- Practice Programming MCQs
- Check Python Books
- Apply for Python Internship