Problem:
In singly linked list, each node contains reference to next node. Address of previous node is not stored in any node, so reverse a singly linked list is a tricky question.
Logic:
For start we will assign previous node as null and currentNode as head of linked list.Till we reach to the last node of list, first store next node in a temporary node and make current node’s next as previous node. Then for next iteration, current node become previous node and nextNode becomes CurrentNode.
Implementation:
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public Node ReverseLinkedList(Node head) { if (head.next == null) { Console.WriteLine(" " + head.val); return head; } Node preNode = null; Node currentNode = head; while (currentNode != null) { Node nextNode = currentNode.next; currentNode.next = preNode; preNode = currentNode; currentNode = nextNode; } head = preNode; return head; } |