Sort a ordered linkedlist

A singly LL is given such that there is alternate ordering between the elements.

Ex: 1->2->13->14->11->5->4->null

Give an efficient O(n) algo to sort such a LL. There can be multiple such orderings in the given LL.

find height of a node in BST

Given a BST T and a node N in T such that all leaf nodes are connected in doubly linkedlist fashion, find height of the node N in T.