Amazon SDE I Intern Interview Experience | Round 1 — Technical Interview

Amazon SDE I Intern | Round 1 - Technical Interview

Hi everyone!

I recently appeared for the Amazon SDE I Intern interview. I am sharing my Round 1 interview experience to help other students preparing for Amazon SDE internship interviews.

Interview Details

• Company: Amazon
• Role: SDE I Intern
• Batch: 2027
• Round: Round 1 - Technical Interview
• Interview Duration: 1 hour (lasted 1 hour 15 minutes)
• Interview Mode: Online

Technical Interview Experience

The interview started with a brief introduction, followed by a discussion about my projects and some behavioral questions. The majority of the interview focused on a single DSA problem, where the interviewer asked me to explore different approaches and optimize the solution.

1. Introduction and Project Discussion

The interview began with my introduction, after which the interviewer asked me about my projects.

2. Behavioral Questions

The interviewer asked me the following behavioral questions:

• Have you made any mistakes while working in a team during the past year?
• Why did you blindly trust your teammates?

These questions focused on teamwork, decision-making, and learning from past experiences.

3. DSA Question: Searching for an Element in a Stream

The interviewer presented a problem involving a stream of elements. New elements arrive over time, and queries can be made at any point to determine whether a particular element exists in the stream.

Before proposing a solution, I asked about the maximum number of elements the stream could contain. Initially, the interviewer asked me to assume that the stream was infinite.

I pointed out that storing an infinite number of elements would not be feasible. After some discussion, the interviewer clarified that the number of elements was limited and that I could store them using a data structure.

We then explored different approaches.

Approach 1: Unordered Set

I proposed using an Unordered_set to store the elements and check whether a queried element existed in the stream.

The interviewer then asked me how an unordered set works internally.

Approach 2: Vector

Next, the interviewer asked me to solve the problem without using an unordered_set or an unordered_map.

I suggested storing the elements in a vector and performing a linear search whenever a query arrived.

• Search time complexity: O(n) in the worst case
• Insertion: O(1) amortized at the end of a vector

The interviewer then asked me to optimize the solution further.

Approach 3: Binary Search Tree (BST)

I suggested using a binary search tree to improve the search time.

I also explained that an ordinary BST could become skewed, resulting in O(n) worst-case search time.

The interviewer then asked how I would handle this issue.

Approach 4: Self-Balancing Binary Search Tree

I suggested using self-balancing BSTs, such as AVL trees and Red-Black trees, to maintain efficient search operations.

We discussed AVL trees in more detail, and the interviewer specifically asked me to write the code for the AVL tree rotation function.

The discussion covered different data structures, their internal working, time complexity, optimization, and the implementation of AVL tree rotations.

Time spent on this problem: Approximately 45–50 minutes.

4. Questions for the Interviewer

Towards the end of the interview, the interviewer asked whether I had any questions.

I asked a few questions, after which the interview concluded.

Good luck to everyone preparing !!