Reverse a doubly circular linked list
The problem is to reverse the given doubly circular linked list.
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insertEnd(head, new_node) Declare last if head == NULL then new_node->next = new_node->prev = new_node head = new_node return last = head->prev new_node->next = head head->prev = new_node new_node->prev = last last->next = new_node reverse(head) Initialize new_head = NULL Declare last last = head->prev Initialize curr = last, prev while curr->prev != last prev = curr->prev insertEnd(&new_head, curr) curr = prev insertEnd(&new_head, curr) return new_head
Explanation: The variable head in the parameter list of insertEnd() is pointer to a pointer variable. reverse() traverses the doubly circular linked list starting with head pointer in backward direction and one by one gets the node in the traversal. It inserts those nodes at the end of the list that starts with the new_head pointer with the help of the function insertEnd() and finally returns new_head.
Current list: Forward direction: 1 2 3 4 5 Backward direction: 5 4 3 2 1 Reversed list: Forward direction: 5 4 3 2 1 Backward direction: 1 2 3 4 5
Time Complexity: O(n).