SDE - 2

You have been given ‘N’ courses and some courses may have prerequisites. Now consider a matrix ‘PREREQUISITES’ of size 'M' x 2 which represents that you must complete the course 'PREREQUISITES[i][1]' before the course 'PREREQUISITES[i][0]'.

Your task is to return the order of courses you should take to finish all courses.

Note:

If it is impossible to finish all courses, return an empty array. If there are multiple answers, return any one.

For example:

Input:
3 2
1 2
2 3

There are three courses to take. To start with, First course 3 is taken. Then course 2 is taken for which course 3 must be completed. 

At last course 1 is taken for which course 2 must be completed. So the correct course order is [3,2,1].    

System design of Netflix. (Learn)

Given a binary tree and the value of two nodes, find the distance between the given two nodes of the Binary Tree.

Distance between two nodes is defined as the minimum number of edges in the path from one node to another.

Given that integers are read from a data stream. Your task is to find the median of the elements read so far.

Median is the middle value in an ordered integer list. If the size of the list is even there is no middle value. So the median is the floor of the average of the two middle values.

For example :

[2,3,4] - median is 3.
[2,3] - median is floor((2+3)/2) = 2.

Design a parking lot. (Learn)