SDE - Intern

You have been given a singly Linked List in the form of 'L1' -> 'L2' -> 'L3' -> ... 'Ln'. Your task is to rearrange the nodes of this list to make it in the form of 'L1' -> 'Ln' -> 'L2' -> 'Ln-1' and so on. You are not allowed to alter the data of the nodes of the given linked list.

For example:

If the given linked list is 1 -> 2 -> 3 -> 4 -> 5 -> NULL.

Then rearrange it into 1 -> 5 -> 2 -> 4 -> 3 -> NULL. 

Given a complete binary tree, you are supposed to return the number of nodes in the given tree.

In a complete binary tree every level, except possibly the last, is completely filled, and all nodes in the last level are as far left as possible.

For example:

For the binary trees in the image below.

The left tree in the image is not a complete binary tree that’s why it is invalid and the right tree in the image is a valid complete binary tree which contains total 6 nodes.

You are given an array/list ARR consisting of N integers. Your task is to find all the distinct triplets present in the array which adds up to a given number K.

An array is said to have a triplet {ARR[i], ARR[j], ARR[k]} with sum = 'K' if there exists three indices i, j and k such that i!=j, j!=k and i!=j and ARR[i] + ARR[j] + ARR[k] = 'K'.

Note:

1. You can return the list of values in any order. For example, if a valid triplet is {1, 2, -3}, then {2, -3, 1}, {-3, 2, 1} etc is also valid triplet. Also, the ordering of different triplets can be random i.e if there are more than one valid triplets, you can return them in any order.
2. The elements in the array need not be distinct.
3. If no such triplet is present in the array, then return an empty list, and the output printed for such a test case will be "-1".

Ninja is in the process of constructing a racecourse, which can be represented as a singly linked list. This list contains ‘N’ checkpoints, each represented as a node, and concludes at the final node.

However, Ninja accidentally connected the final checkpoint of the racecourse to the ‘Kth’ checkpoint (indexed from 0), creating an infinite loop for the racecars.

Your task here is to remove all the checkpoints that are in the loop and print the racecourse after the removal of the loop.

Refer example for better understanding.

Example :

 N = 4
 K = 1
 NODE = 1->2->3->4

You can see there is a loop from the ‘1st’ node to the ‘3rd’ node (0 based), so we will remove all nodes from (1 - 3), so the answer is [ 1 ].