Amazon SDE Intern Interview Experience~ 2 Rounds, 4 Coding Problems | Selected

Interview Overview

• Role: SDE Intern
• Company: Amazon
• Experience Level: Fresher
• Interview Date: October 2025
• Result: Selected
• Rounds: 2 Interview Rounds + Online Assessment
• Total Coding Problems: 4
• Mode: Campus Placement

Interview Preparation Journey

My preparation journey was focused less on shortcuts and more on building strong fundamentals consistently over time. Instead of chasing only interview-specific tricks, I spent most of my preparation understanding the core concepts of computer science deeply, especially Data Structures, Algorithms, Operating Systems, OOP, DBMS and problem-solving techniques.

In the beginning, progress felt slow. Solving coding problems often took a lot of time and many concepts seemed difficult initially. However, regular practice and reviewing mistakes carefully helped me improve gradually. One important lesson I learned was that interview preparation is not about solving hundreds of random problems blindly; it is about understanding patterns, improving reasoning ability and learning how to approach unfamiliar questions logically.

Alongside coding preparation, I also worked on projects and internships that helped me understand how real systems work in production environments. These experiences improved my debugging skills, taught me how to think under pressure and strengthened my understanding of software engineering beyond just DSA questions. There were also difficult phases during the preparation journey:

• rejections
• self-doubt
• comparison with others
• inconsistent confidence

But instead of treating setbacks as failures, I used them as feedback. Whenever I struggled in a topic or interview, I revisited fundamentals, identified weak areas and refined my preparation strategy. By the time the Amazon interview arrived, preparation no longer felt like last-minute pressure. It felt like the natural result of months of consistent effort and disciplined learning.

One of the biggest lessons I learned from this journey is: Strong fundamentals, consistency and patience matter far more than shortcuts.

Application Process

I applied for the role through my college’s on-campus placement process after the opportunity was shared by the placement cell. The process was structured clearly and communication regarding each round was smooth throughout the recruitment cycle. The application journey included:

• Resume shortlisting
• Online Assessment
• Technical Interview Round

After successfully clearing all stages, I received the final selection confirmation for the SDE Intern role.

Why I Think I Was Selected

I believe my selection was not based only on coding ability but on a combination of multiple factors:

• Strong CS fundamentals
• Consistent problem-solving approach
• Clear explanation of thought process
• Good understanding of projects
• Ability to discuss trade-offs and optimizations
• Calm communication during interviews

One thing I noticed during the process was that interviewers cared not only about arriving at the correct solution, but also about:

• how clearly the approach was explained
• how edge cases were handled
• how logically the problem was broken down
• how confidently decisions were justified

This reinforced an important realization: Communication and clarity are as important as coding skills in technical interviews.

Preparation Strategy

Preparation Duration

Approximately 3 months of focused preparation.

Main Topics Covered

• Data Structures and Algorithms
• Object-Oriented Programming
• Operating Systems
• Database Management Systems
• Computer Networks
• Problem Solving
• Coding Practice
• Basic System Design

My preparation mainly focused on strengthening core concepts and practicing coding patterns repeatedly rather than memorizing solutions. Many interview questions eventually become manageable once you develop strong pattern-recognition skills.

Preparation Tips

Tip 1: Focus on Fundamentals

Strong fundamentals are far more valuable than memorizing tricks. Understanding why an approach works is more important than remembering solutions.

Tip 2: Practice Consistently

Daily problem solving builds confidence gradually. Consistency matters more than occasional long study sessions.

Tip 3: Explain Your Thinking Out Loud

One of the most underrated interview skills is communication. During interviews, explaining your approach clearly is extremely important. Amazon interview preparation resources and candidate experiences repeatedly emphasize communication and thought-process explanation during coding rounds.

Tip 4: Review Mistakes Properly

After solving problems, spend time analyzing:

• why the mistake happened
• what optimization was missed
• how the solution could improve

This accelerates learning significantly.

Resume Tips

Tip 1: Keep Resume Clean and Concise

A one-page resume with clear formatting and readable bullet points creates a better impression.

Tip 2: Focus on Impact

Instead of listing only technologies, explain:

• performance improvements
• scale handled
• measurable outcomes
• optimization impact

Tip 3: Understand Everything You Mention

Interviewers may deeply discuss any project or technology written on the resume. Only include topics you genuinely understand.

Tip 4: Avoid Buzzwords

Using unnecessary buzzwords without understanding them often creates negative impressions during technical discussions.

Interview Round 1 : Online Assessment

• Difficulty: Medium
• Duration: 90 Minutes
• Date: 4 October 2025
• Problems Solved: 2 Coding Questions

The Online Assessment focused heavily on:

• problem-solving ability
• coding accuracy
• DSA fundamentals
• optimization thinking
• time management

The questions were medium-level and required both correctness and efficient implementation.

Problem 1: Longest Substring Without Repeating Characters

Problem Type Sliding Window / Two Pointer Pattern Difficulty Moderate

Given a string, find the length of the longest substring without repeating characters.

My Approach

I identified this as a classic Sliding Window problem. The brute-force approach would check all substrings, resulting in high time complexity. Instead, I used:

• two pointers
• a HashSet / HashMap
• dynamic window expansion and shrinking

Steps

1. Maintain left and right pointers

2. Expand the right pointer

3. Store characters in current window

4. If duplicate appears:

   • shrink the window from left

5. Update maximum length continuously

This optimized the solution to linear complexity.

Key Learning

This problem reinforced how important pattern recognition is in coding interviews. Once the Sliding Window pattern becomes familiar, many substring problems become significantly easier.

Problem 2: Rotting Oranges

Problem Type : Graph Traversal (Multi-Source BFS) Difficulty : Moderate

Given a grid containing fresh and rotten oranges, determine the minimum time required to rot all oranges.

My Approach

I recognized this as a BFS traversal problem because the infection spreads level by level.

Steps

1. Traverse the grid initially
2. Push all rotten oranges into a queue
3. Count fresh oranges
4. Perform BFS simultaneously from all rotten oranges
5. Process each BFS level as one minute
6. Rot adjacent fresh oranges
7. Continue until queue becomes empty

Important Insight

The key realization was understanding that this is not normal BFS from a single source. It is: Multi-Source BFS This pattern appears frequently in graph and matrix interview problems.

Interview Round 2 : Technical Video Interview

• Difficulty: Medium
• Duration: 60 Minutes
• Date: 9 October 2025
• Problems Solved: 2 Coding Questions

The interview environment was professional, calm and well-structured. The interviewer was polite and encouraged discussion throughout the session. One thing I noticed was that the interviewer focused heavily on:

• thought process
• clarity of explanation
• optimization reasoning
• edge-case discussion

instead of only final code correctness. This aligns with many recent Amazon candidate experiences where communication and reasoning clarity are strongly evaluated alongside coding ability.

Problem 1: Basic Calculator II

Problem Type : Stack / Expression Parsing Difficulty : Moderate

You are given a string ‘STR’, which represents an expression. Your task is to evaluate the value of the expression. The integer division should truncate toward zero. For Example: Consider STR = "3+2*2" Using the BODMAS rule, the expression after evaluation gives 7. Hence, the answer is 7.

My Approach

Instead of using a full stack-heavy parser, I implemented a one-pass optimized solution.

Steps

1. I noted that the expression has no brackets, only operators with precedence.
2. Traverse the string character by character
3. Build numbers dynamically
4. Process operators immediately
5. Handle multiplication/division instantly
6. Handle addition/subtraction using accumulated result

Key Learning

The interviewer was interested not only in correctness but also in:

• why this approach was chosen
• time complexity
• space optimization
• handling precedence efficiently

This made discussion clarity extremely important.

Problem 2: Find The Single Element

Problem Type : Bit Manipulation (XOR) Difficulty : Easy

In a sorted array where every element appears twice except one, find the unique element.

My Approach

I used the XOR property:

• a ^ a = 0
• a ^ 0 = a

Steps

1. Initialize result as 0
2. XOR every element
3. Duplicate values cancel each other
4. Remaining value becomes the answer

Key Insight

Even though the problem itself was simpler compared to previous questions, the interviewer still evaluated:

• explanation clarity
• confidence
• reasoning ability
• edge-case awareness

Final Thoughts

One of the biggest lessons from this interview experience was: Technical knowledge alone is not enough to clear interviews at top companies.

Interviewers also evaluate:

• communication
• structured thinking
• problem-solving clarity
• confidence
• project understanding

Strong coding skills may help you clear assessments, but your ability to explain your reasoning clearly often becomes the deciding factor during interviews. For candidates preparing for Amazon or similar product-based companies, I would strongly recommend:

• focus on fundamentals
• practice coding patterns deeply
• explain your thinking while solving problems
• revise projects thoroughly
• stay consistent instead of rushing preparation

Interview preparation is rarely about sudden breakthroughs. Most of the time, success is simply the result of consistent effort repeated over a long period.