I got the placement when the company visited my campus. There were 4 rounds to qualify for finals.

The first round was an aptitude test where they asked data structure MCQs and aptitude questions. The time limit to solve all the problems was quite limited, so time management was crucial. The data structure questions covered linked lists, trees, BSTs, and AVL trees. One having good knowledge of Java could have solved the problems easily.

The second round was a coding round where we were given two coding questions to solve online. The first question was a brute-force approach problem, and the second required graph implementation.

Technical Round 1:

• Brief introduction of myself.
• Then, I was asked how I would create a database of people with Aadhaar number, name, and father’s name.
• The second question was to implement a calculator that performs basic operations: +, -, *, and /.

I was asked to write full, working code with boundary cases handled in C, C++, or Java. Then, the interviewer went through my resume and, after I wrote the code, asked me to explain it. He also inquired how I would extend my code to handle scientific calculations like sin(x), cos(x), etc.

After reviewing my resume, he asked me to explain a recently solved question from an online programming platform. I had recently solved a Codeforces Div 2 question and explained it to him. He also asked about my approach to solving it. I walked him through the solution, demonstrating the optimization from O(n^2) to O(n) complexity.

Technical Round 2:

• Brief introduction of myself.

• Difference between an array and a linked list, and the advantages of an array over a linked list.

• Which language I preferred between C and C++, and why.

• My favorite data structure and algorithm, and why. I replied with 'array' and 'DFS' and explained my reasoning.

• Why I was interested in Data Structures and Algorithms.

• Which data structure, between an array and a linked list, I would prefer for 10, 100, and 1000 elements. I had to provide answers in terms of both time and space complexity.

• Consider the following code: cpp class A { ... }; A ob; // Declaration 1 A *ptr = new A(); // Declaration 2

  What is the difference between these two declarations?

• To write code explaining the working of a copy constructor.

• Static classes.

• Given a linked list of size 'N', how would I delete the 5th element from the last?

• He asked me to write working code for reversing a linked list.

• Difference between calloc and malloc. He also asked for the syntax of both.

• Given a stack and a queue. At any point, let the stack hold N1 elements and the queue hold N2 elements.

  1. If N1 and N2 are both odd, swap the middle elements of the stack and the queue.
  2. If N1 and N2 are both even, there would be two middle elements in the stack and two in the queue. Out of these four elements, swap the maximum element with the minimum element.
  3. Do nothing otherwise.

Although I couldn’t solve the question fully, I presented my approach. He suggested I solve it using the min-stack algorithm and implementing a queue using two stacks.

• Why I started competitive programming.