ALT Problem: Two Sum IV - Input is a BST Problem Statement: You have been given a Binary Search Tree and a target value. You need to find out whether there exists a pair of node values in the BST, such that their sum is equal to the target value. A binary search tree (BST), also called an ordered or sorted binary tree, is a rooted binary tree whose internal nodes each store a value greater than all the values keys in the node's left subtree and less than those in its right subtree.

ALT Problem: LCA Of Binary Tree Problem Statement: You have been given a Binary Tree of distinct integers and two nodes ‘X’ and ‘Y’. You are supposed to return the LCA (Lowest Common Ancestor) of ‘X’ and ‘Y’. The LCA of ‘X’ and ‘Y’ in the binary tree is the shared ancestor of ‘X’ and ‘Y’ that is located farthest from the root. Note : You may assume that given ‘X’ and ‘Y’ definitely exist in the given binary tree.

ALT Problem: N Queue Using Array Problem Statement: You will be given ‘N’ queries. You need to implement ‘N’ queues using an array according to those queries. Each query will belong to one of these two types: 1 ‘X’ N: Enqueue element ‘X’ into the end of the nth queue. Returns true if the element is enqueued, otherwise false. 2 N: Dequeue the element at the front of the nth queue. Returns -1 if the queue is empty, otherwise, returns the dequeued element. Note: Please note that Enqueue means adding an element to the end of the queue, while Dequeue means removing the element from the front of the queue.

ALT Problem: Circular Tour Problem Statement: You have been given a circular path. There are N petrol pumps on this path that are numbered from 0 to N - 1 (Both inclusive). Each petrol pump has two values associated with it: 1)The amount of petrol that is available at this particular petrol pump. 2)The distance to reach the next petrol pump. You are on a truck having an empty tank of infinite capacity. You can start the tour from any of the petrol pumps. Your task is to calculate the first petrol pump from where the truck will be able to complete the full circle or determine if it is impossible to do so. You may assume that the truck will stop at every petrol pump and it will add the petrol from that pump to its tank. The truck will move one kilometre for each litre of petrol consumed.