Find the sum of last n nodes of the given Linked List
Given a linked list and a number n. Find the sum of the last n nodes of the linked list.Constraints: 0 <= n <= number of nodes in the linked list. Examples: Input : 10->6->8->4->12, n = 2 Output : 16 Sum of last two nodes: 12 + 4 = 16 Input : 15->7->9->5->16->14, n =