SDE - 1

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 have been given a binary tree of integers with N number of nodes. Your task is to check if that input tree is a BST (Binary Search Tree) or not.

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.

Example :

Answer :

Level 1: 

All the nodes in the left subtree of 4 (2, 1, 3) are smaller 
than 4, all the nodes in the right subtree of the 4 (5) are 
larger than 4.

Level 2 :

For node 2:
All the nodes in the left subtree of 2 (1) are smaller than 
2, all the nodes in the right subtree of the 2 (3) are larger than 2.
For node 5:
The left and right subtrees for node 5 are empty.

Level 3:

For node 1:
The left and right subtrees for node 1 are empty.
For node 3:
The left and right subtrees for node 3 are empty.

Because all the nodes follow the property of a binary search tree, the above tree is a binary search tree.

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 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.

You are given an expression 'exp' in the form of a string where operands will be : (TRUE or FALSE), and operators will be : (AND, OR or XOR).

Now you have to find the number of ways we can parenthesize the expression such that it will evaluate to TRUE.

As the answer can be very large, return the output modulo 1000000007.

Note :

‘T’ will represent the operand TRUE.
‘F’ will represent the operand FALSE.
‘|’ will represent the operator OR.
‘&’ will represent the operator AND.
‘^’ will represent the operator XOR.

Example :

Input: 'exp’ = "T|T & F".

Output: 1

Explanation:
There are total 2  ways to parenthesize this expression:
    (i) (T | T) & (F) = F
    (ii) (T) | (T & F) = T
Out of 2 ways, one will result in True, so we will return 1.

Get alternative odd records from the Employees table

Design an Elevator system. And then write an algorithm for that Design such that the user request should be completed in logN time in an N story building with M elevators.