SDE - 1

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. 

You are a student of Netaji Subhas Institute of Technology. You have to take ‘N’ number of courses labelled from 1 to N to complete your B.Tech Degree.

Some courses may have prerequisites, for example, to take course 1 you have to first take course 2, which is expressed as a pair: [1, 2]. Now, your task is to find is it possible for you to finish all courses.

Note: There are no duplicate pairs in the prerequisites array.

For example-

If N = 2 and prerequisite = [[1, 2]]. Then, there are a total of 2 courses you need to take. To take course 1 you need to finish course 2. So, it is possible to complete all courses. 

You are given an array 'ARR' of N integers. Each integer represents the height of a balloon. So, there are N balloons lined up.

Your aim is to destroy all these balloons. Now, a balloon can only be destroyed if the player shoots its head. So, to do the needful, he/ she shoots an arrow from the left to the right side of the platform, from an arbitrary height he/she chooses. The arrow moves from left to right, at a chosen height ARR[i] until it finds a balloon. The moment when an arrow touches a balloon, the balloon gets destroyed and disappears and the arrow continues its way from left to right at a height decreased by 1. Therefore, if the arrow was moving at height ARR[i], after destroying the balloon it travels at height ARR[i]-1. The player wins this game if he destroys all the balloons in minimum arrows.

You have to return the minimum arrows required to complete the task.

Given a singly linked list of integers. Your task is to return the head of the reversed linked list.

For example:

The given linked list is 1 -> 2 -> 3 -> 4-> NULL. Then the reverse linked list is 4 -> 3 -> 2 -> 1 -> NULL and the head of the reversed linked list will be 4.

Follow Up :

Can you solve this problem in O(N) time and O(1) space complexity?

Given two binary trees T and S, check whether tree S has exactly the same structure and node values with a subtree of T, i.e., check if tree S is a subtree of the tree T.

A subtree of a tree T is a tree S consisting of a node in T and all of its descendants in T. The subtree corresponding to the root node is the entire tree; the subtree corresponding to any other node is called a proper subtree.

You have been given a grid containing some oranges. Each cell of this grid has one of the three integers values:

Value 0 - representing an empty cell.

Value 1 - representing a fresh orange.

Value 2 - representing a rotten orange.

Every second, any fresh orange that is adjacent(4-directionally) to a rotten orange becomes rotten.

Your task is to find out the minimum time after which no cell has a fresh orange. If it's impossible to rot all the fresh oranges then print -1.

Note:

1. The grid has 0-based indexing.
2. A rotten orange can affect the adjacent oranges 4 directionally i.e. Up, Down, Left, Right.

They asked questions about two of my projects. For one, they went in depth while for other they just skimmed it,
In the end, they asked what are you most excited about for joining Rupeek? What you'll bring to table?