HackerEarth

Role: Problem Setter Intern

College: Not Specified

Interview Date: Not Specified

Interview Type: Internship, Referral

Result: Selected

Difficulty: Medium to Hard

Rounds: 4 rounds

Topics Asked: Data Structures and Algorithms, Competitive Programming, Prime Number Theory, Inclusion-Exclusion Principle, DSU, String Hashing, KMP, Graph algorithms

Experience:

This candidate secured a Problem Setter Intern role at HackerEarth through a referral. The preparation involved practicing on various coding websites like Codechef, Codeforces, Atcoder, and HackerEarth for 1-4 months, focusing on Data Structures and Algorithms and competitive programming.

Round 1: Online Coding Test

This round consisted of 3 coding questions. Two were of Codeforces Div2 B/C level, and one was a Codeforces Div2 D level problem requiring prime number theory and the inclusion-exclusion principle.

Round 2: Video Call and HackerEarth's FacePrep

This round focused on Data Structures and Algorithms and involved 3 problems.

• Problem 1: Given a string, find the number of substrings with an equal number of all five vowels. Example: Input: N = 6, S = "aeioua", Output: 2 (Substrings "aeiou" and "eioua").
• Problem 2: Given a number N, find the number of even factors of N!. Example: Input: N = 3, Output: 2 (Even factors 2 and 6).
• Problem 3: The exact problem was not remembered, but the candidate initially solved it with an O(NlogN) binary search approach and later optimized it to an O(N) two-pointer solution.

After these coding questions, the interviewers asked various questions from DSU (Disjoint Set Union), String Hashing, KMP (Knuth-Morris-Pratt algorithm), and Graph algorithms.

Round 3 & 4: Team Lead and Hiring Manager Rounds

These were two separate rounds, one with the Team Lead of the problem setter team and another with the hiring manager. The specific details of these rounds are not provided, but they are typically focused on behavioral aspects, project discussions, and cultural fit.

Verdict: Selected.

Message to Aspiring Students: The candidate advised that competitive programming experience and deep DSA knowledge are crucial. It's important to review DSA topics before the interview as questions will be asked.