Senior Software Engineer

You are given an array ‘ARR’ of ‘N’ integers, you need to find the maximum length of the sub-array such that the product of elements of the sub-array is positive.

For Example:

Let us say we have array 'ARR' =[-1,3,5,-2,4,-9]. The longest sub-array with the positive product is [3,5,-2,4,-9]. 

You are given an array/list 'prices' where the elements of the array represent the prices of the stock as they were yesterday and indices of the array represent minutes. Your task is to find and return the maximum profit you can make by buying and selling the stock. You can buy and sell the stock only once.

Note:

You can’t sell without buying first.

For Example:

For the given array [ 2, 100, 150, 120],
The maximum profit can be achieved by buying the stock at minute 0 when its price is Rs. 2 and selling it at minute 2 when its price is Rs. 150.
So, the output will be 148.

You are given the root of a complete binary tree, you need to calculate the number of nodes in the given complete binary tree.

A complete binary tree is a tree in which all the levels are completely filled except the last level. Nodes in the last level are as left as possible.

For Example:

In the above complete binary tree, all the levels are filled except for the last. In the last level, all the nodes in the last level are as far left as possible.

Explain Polymorphism
What is Method Overloading & Method Overriding
Explain Inheritance
What are Abstract Classes
Explain Pure Virtual Functions.

You are given two integers N and M. Can you find a number closest to N and divisible by M.

Here closest number to N means a number whose absolute difference is minimum with N. If there are two integers closest to N then the answer will be the one which is a smaller integer.

For Example:

Let N = 8 and M = 3
The numbers divisible by 3 are 3, 6, 9, …
From these numbers 9 is closest to 8. Thus, the answer is 9.

What is thrashing
What is caching
Explain mutex locks

Design a system, that will help us to store the details of a person, countries he visited & where he stayed in the country & other details.

The values should not get changed by the process in between when we fetch it. This means once stored, it will not change forever (i.e It should be Immutable). 

I told him that we can use unordered_map to store person's details. He said that he wanted to see Low Level Design for this.

What are Mutable Objects & Immutable Objects.?
How can you create Immutable objects, so that they don't get changed while processing by CPU?
Give real life scenario for both mutable & Immutable objects.

You have been given a Binary Tree where the value of each node is either 0 or 1. Your task is to return the same Binary Tree but all of its subtrees that don't contain a 1 have been removed.

Note :

A subtree of a node X is X, plus every node that is a descendant of X.

For Example :

Look at the below example to see a Binary Tree pruning.
Input: [1, 1, 1, 0, 1, 0, 1, 0, 0, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1]

Output: [1, 1, 1, -1, 1, -1, 1, -1, -1, -1, -1]

For example, the input for the tree depicted in the below image would be :

1
2 3
4 -1 5 6
-1 7 -1 -1 -1 -1
-1 -1

Explanation :

Level 1 :
The root node of the tree is 1

Level 2 :
Left child of 1 = 2
Right child of 1 = 3

Level 3 :
Left child of 2 = 4
Right child of 2 = null (-1)
Left child of 3 = 5
Right child of 3 = 6

Level 4 :
Left child of 4 = null (-1)
Right child of 4 = 7
Left child of 5 = null (-1)
Right child of 5 = null (-1)
Left child of 6 = null (-1)
Right child of 6 = null (-1)

Level 5 :
Left child of 7 = null (-1)
Right child of 7 = null (-1)

The first not-null node (of the previous level) is treated as the parent of the first two nodes of the current level. The second not-null node (of the previous level) is treated as the parent node for the next two nodes of the current level and so on.
The input ends when all nodes at the last level are null (-1).

Note :

The above format was just to provide clarity on how the input is formed for a given tree.

The sequence will be put together in a single line separated by a single space. Hence, for the above-depicted tree, the input will be given as:
1 2 3 4 -1 5 6 -1 7 -1 -1 -1 -1 -1 -1