Amazon SDE-1 Interview Experience (March - April 2025)

I recently completed my SDE-1 interview process at Amazon. The overall experience was intense yet rewarding. Here’s a detailed breakdown of all the rounds:

📅 Round 1 – Technical Interview

Note: This round was rescheduled twice.

1. OOPs Implementation Question
Given student data with fields: rollNo (alphanumeric and unique), marks, name, rank (not unique), etc.
Task:

• Write classes and functions to:
  • Retrieve all students for a given rank.
  • Retrieve a student by their roll number.

My Approach:
I used two HashMaps:

• One for mapping rollNo to Student.
• One for mapping rank to a list of Students.

The interviewer was satisfied with the approach.

Follow-up:

• Asked how HashMap works internally.
• I explained the underlying structure: array of buckets, hashing, handling collisions (via chaining or open addressing), resizing, etc.
• Based on this, he asked a few in-depth follow-up questions.

2. Binary Tree – Count Nodes with Two Children
Problem: Count the number of nodes in a binary tree that have both left and right children.
My Approach: Implemented using post-order traversal (recursive).

Follow-up:
He asked me to solve it iteratively, but I was unable to implement the iterative version in time.

📅 Round 2 – DSA + Leadership Principles

Note: This round was initially scheduled on some other date, but the interviewer didn’t show up and it was rescheduled.

1. Leadership Principle Question
Q: Tell me about a time when you were learning something that wasn’t part of your job. .

2. Follow-up:
Q: What did you like most about that technology?

3. String Compression Variant
Problem:
Given a string, replace each group of consecutive characters with the character and its count. If the count goes beyond 9, than start the counting again.

• s = "aaabbc" → a3b2c1
• s = "aaaaaaaaaaabbbcc" → a9a2b3c2

Status: Solved with an optimized solution.

4. Beautiful Nodes in a Graph
Problem:
Given an n x n adjacency matrix, find all beautiful nodes.

• matrix[i][j] = 1 means node i is connected to node j.
• A node is beautiful if:
  • It is connected to all other nodes.
  • No node is connected to it.

Status: Solved with correct and optimized solution.

📅 Round 3 – Leadership + DSA

1. Leadership Principle:
Q: Tell me about a time when you had to deep dive to solve a particular problem.
Cross-questions followed to test depth and clarity.

2. Leadership Principle:
Q: Tell me about a time when you received negative feedback and how you handled it.
More follow-up questions on this as well.

3. DSA – Longest Substring with All Distinct Characters
Problem: Given a string, return the length of the longest substring with all distinct characters.
Status: Solved with an optimized sliding window approach.

✅ Final Outcome

At the end of the third round, the interviewer said:

"Recruiter will reach out for next steps."

Which strongly indicates selection. 🎉

🔚 Final Thoughts

• Interviewers were very friendly and professional.
• Questions tested both depth of knowledge and problem-solving skills.
• Strong emphasis on Amazon Leadership Principles.
• Don't create fake answers for leadership principle questions because interviewer can ask cross questions and you might get into trouble.
• No core subjects asked, only LP and DSA questions.
• To prepare for leadership principles create few stories from your past experiences and form answers for each leadership principle.

Hope this helps others preparing for Amazon!