SDE - Intern

You are given a Binary Tree.

Return the length of the diameter of the tree.

Note :

The diameter of a binary tree is the length of the longest path between any two end nodes in a tree.

The number of edges between two nodes represents the length of the path between them.

Example :

Input: Consider the given binary tree:

Output: 6

Explanation:
Nodes in the diameter are highlighted. The length of the diameter, i.e., the path length, is 6.

You are given an array of integers 'ARR' of length 'N' and an integer Target. Your task is to return all pairs of elements such that they add up to Target.

Note:

We cannot use the element at a given index twice.

Follow Up:

Try to do this problem in O(N) time complexity. 

Although it was an HR round but this question was quite a mix of tech+HR round. Some puzzles and guesstimates were asked.

If we light a stick, it takes 60 minutes to burn completely. What if we light the stick from both sides? It will take exactly half the original time, i.e. 30 minutes to burn completely.

0 minutes – Light stick 1 on both sides and stick 2 on one side.

30 minutes – Stick 1 will be burnt out. Light the other end of stick 2.

45 minutes – Stick 2 will be burnt out. Thus 45 minutes is completely measured.