SDE - 1

You are given an array/list 'ARR' of ‘N’ integers and an integer value ‘TARGET’. You need to check whether there exist four numbers (ARR[i], ARR[j], ARR[k], ARR[l]) such that (0 <= i < j < k < l < N) and ARR[i] + ARR[j] + ARR[k] + ARR[l] = 'TARGET'.

Note:

1. All four numbers should exist at different indices in the given array.
2. The answer is case-sensitive.

Given a singly linked list, you have to detect the loop and remove the loop from the linked list, if present. You have to make changes in the given linked list itself and return the updated linked list.

Expected Complexity: Try doing it in O(n) time complexity and O(1) space complexity. Here, n is the number of nodes in the linked list.

You are given a binary search tree of integers with N nodes. You are also given references to two nodes 'P' and 'Q' from this BST.

Your task is to find the lowest common ancestor(LCA) of these two given nodes.

The lowest common ancestor for two nodes P and Q is defined as the lowest node that has both P and Q as descendants (where we allow a node to be a descendant of itself)

A binary search tree (BST) is a binary tree data structure which has the following properties.

• The left subtree of a node contains only nodes with data less than the node’s data.
• The right subtree of a node contains only nodes with data greater than the node’s data.
• Both the left and right subtrees must also be binary search trees.

For example:

'P' = 1, 'Q' = 3
tree = 2 1 4 -1 -1 3 -1 -1 -1,

The BST corresponding will be- 

Here, we can clearly see that LCA of node 1 and node 3 is 2.

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".

Was given a schema and for which SQL queries were asked

About myself and what I did new in the lockdown. Had a healthy discussion