Airtel

Role: FTE (Software Development Engineer)

College: Not Specified

Interview Date: 2024-10-01

Interview Type: On-Campus

Result: Selected

Difficulty: Medium

Rounds: 3 rounds

Topics Asked: Data Structures, Complexity Analysis, Aptitude, Coding (String rolling problem, Max occurrences of substring with constraints), Academic Projects, Database Concepts (critical section problem, thread concurrency, shared/binary locks, Timestamp methods, server-client architecture related to threads, ACID properties), Convert Binary tree into Mirror tree, Reverse a linked list, Insertion/deletion/extractMin in heap, Multithreading, Singleton class, Consistency of database, HR questions.

Experience:

The recruitment process started with resume shortlisting, followed by an Online Round on HackerRank. The online test had two sections: 20 MCQs (20 mins) on data structures, complexity analysis, and aptitude, and 2 coding questions (45 mins).

Coding Questions:
1. Given a string `s` and an array `roll` where `roll[i]` represents rolling the first `roll[i]` characters. Apply every `roll[i]` on the string and output the final string (rolling 'z' results in 'a', 'b' to 'c', etc.). Constraints: 1<=|s|<=10^5, 1<=roll[i]<=10^5. Example: Input: bca, 3, 1 2 3 -> Output: eeb.
2. Given a string `s`, find the maximum number of occurrences of a substring that follows constraints: `minLength <= L <= maxLength` (L is substring length) and `number of unique characters in substring <= maxUnique`. Given: 1<=minLength<=|s|, 1<=maxLength<=|s|, 1<=maxUnique<=26. Example: Input: abcdd, 1 2 3 -> Output: 2 (considering substring 'd').
11 students were shortlisted for PI rounds after this.

Technical Round 1 (1+ hour)
The interviewer started with "Tell me about yourself" and then discussed academic projects in detail, especially those related to database concepts. Questions covered critical section problems, thread concurrency, shared and binary locks, Timestamp methods, server-client architecture related to threads, and ACID properties of DBMS. Coding questions included: 1. Convert Binary tree into Mirror tree. 2. Reverse a linked list. 3. Insertion, deletion, extractMin, etc., in a heap. The interviewer was "kind of chill."

Technical Round 2
The interviewer asked about the first technical round. Questions were then asked about multithreading and related concepts. There was a detailed discussion on a solution provided by the candidate (likely from the previous round or a new problem). Topics like Singleton class and consistency of the database were also discussed.

HR Round (1+ hour)
The HR round involved situational questions like managing pressure, convincing a team/boss about a different approach, and future plans (MBA/MS/MTech). Questions about potential offers from "big companies" were also posed. The candidate was selected after this round.