Hi, I recently went through the interview process at Amazon. In April, a recruiter from Naukri.com reached out to me regarding the SDE1 position at Amazon.
Timeline: The complete process took around 1.5 months.
Online Assessment: Platform: HackerRank. 2 Questions of medium difficulty level to be solved in 60 minutes. I had to write code as well as explain the approach, how I came up with the solution, and mention the time and space complexity of the problems.
- Given an array, return the index of the pair in the array whose sum is K. If there is more than one pair, return the index of the pair which has the biggest individual element. Similar to https://www.geeksforgeeks.org/given-an-array-a-and-a-number-x-check-for-pair-in-a-with-sum-as-x/
- A book is represented by a Binary string having two types of pages, ‘0’ is an ordinary page, and ‘1’ is bookmarked page. Find the number of ways to select 3 pages in ascending index order such that no two adjacent pages are of the same type.
There were some behavioral questions as well. And some MCQ questions on Workstyle.
This round went well. I was able to solve all the questions in the given time. One week later I got a call from HR saying that my Online Assessment went well. And they’ll be moving forward with the next rounds. She told me there will be 3 more rounds. 2 Technical rounds, and 1 BarRaiser Round (This is a decider round).
My two technical rounds were scheduled for the 20th of April.
Technical Round 1: This round went on for 70 minutes. The interviewer introduced himself and ask a little about me then directly jumped into questions.
- First Question: https://www.geeksforgeeks.org/maximum-width-of-a-binary-tree-with-null-value/amp/
- He asked about my approach and time complexity then he asked me to implement it. I was able to write code for it with all cases covered.
- Second Question: Find whether it is possible to finish all tasks or not from given dependencies
- I had already practiced this question. I solved it using DFS. I maintained two visited arrays. I explained the approach and then he asked me to code.
I was able to code both questions within the given time, and the interviewer was impressed. He then asked me if I had any questions.
Technical Round 2: This round happened on the same day. It went on for an hour. The interviewer introduced himself and ask a little about me then directly jumped into questions. This round had one coding question + one behavioral question based on the Amazon Leadership principle.
-
First Question: Rotten Oranges.
- I explained to him the BFS-based approach using a queue. He asked me how would I make sure that all fresh oranges have been rotten and no fresh oranges are remaining. I told him after the BFS we could go through the matrix and see if there is any 1 available. He then asked me to check it without doing this extra traversal (As we are already doing one traversal for pushing all the first instances of 2 (rotten oranges) in the queue). I told him that we would keep a variable one_count and during the first traversal, we’ll check for 1 and increment the counter. And whenever we push a ‘1’ to queue for BFS we’ll decrement the one_count. Now after the BFS is done we’ll check if one_count == 0, meaning no fresh orange is left. He was happy with my solution. He asked to write full working code and I was able to code it.
-
Second Question: Tell me about a time when you felt challenged at work. How did you handle being challenged?
- You have to answer this leadership question by Keeping the STAR method in mind. I had a similar experience in my current company so I was able to explain it.
He then asked me if I had any questions. I then asked him about his current role and the projects he is working on.
The recruiter called me 2 days later and told me that I have cleared both rounds and they’ll be having one more round called the BARRAISER round, which is the decider round. I asked her when can we have the last round she told me that she doesn’t know when can we have the final round as getting slots for the Barraiser round is very difficult. She told me that she’ll update me 3-4 days before the interview.
Till here the interview process was going smooth. But from here the process started getting tidy.
I waited two weeks and there was no response from the Recruiter. I called her 2-3 times asking if there was any update but no response from her side. Then suddenly on 8th May at midnight (around 12:30 AM), I received an email from the recruiter saying I have my final round today at 2:00 PM. I was asleep at that time. I woke up the next morning around 10:00 AM and saw the mail. I only had 4 hours till my final interview. I called the recruiter to see if it can be rescheduled as I was not free that day. I had a meeting at the same time. But the recruiter told me that interview can’t be rescheduled. Somehow I managed and gave the interview that day at 2:00 PM.
BARRISTER ROUND: The interviewer introduced himself and ask a little about me then directly jumped into questions. This round was mainly based on Amazon LP. It also had one coding question.
The interview started with Leadership questions.
Leadership Questions
- Tell me about a time when you took a calculated risk.
- Tell me about a time when you went above and beyond to fulfill customers’ expectations.
- Tell me about a time when you did something that you are proud of. (Professional)
- Tell me the coolest thing that you have ever done.
- Tell me about a time when you had to react quickly to a problem. What was the outcome?
He went deep into all the questions and kept asking follow-up questions.
PS: always try to use real-life scenarios for these types of questions.
Coding Question
-
Sliding Window Maximum (Maximum of all subarrays of size k)
- I first told him about the brute force approach of O(n2). He then asked me to optimize it.
- I then told him the approach of using max_heap, I told him that we would store the index as well as the array element in max_heap. We’ll first insert k elements in max_heap and append the top of max_heap to our result vector. And if the top of maxheap doesn’t lie in the range of I -> i-k, then we’ll pop the element otherwise we’ll keep it in the max_heap.
vector<int> max_of_subarrays(vector<int> arr, int n, int k) {
priority_queue<pair<int, int>> pq;
for(int i = 0; i < k; i++){
pq.push({arr[i], i});
}
vector<int> ans;
ans.push_back(pq.top().first);
for(int i = k ; i < arr.size(); i++){
pq.push({arr[i], i});
while(pq.top().second <= (i - k)){
pq.pop();
}
ans.push_back(pq.top().first);
}
return ans;
} |
He asked me to explain the complete approach and asked for time complexity. I told them that it’s O(log) as the heap size at any moment can not be more than K. He didn’t seem satisfied with the solution. He then asked me to implement it. I was able to write the code and he dry ran the code against many cases. It was working fine. It was more than an hour by the time he was done checking the code. He was still not looking completely satisfied. He was probably looking for a more optimized solution, but we were already running out of time. He wrapped up the session. I knew about the linear time solution of this problem using deque but it didn’t come to my mind during the interview. He was probably looking for a dequeue-based approach but I couldn’t think of that. The best I thought was the heap-based approach of nlogk.
I was disappointed after this round as I knew. I had bombed my interview. The last round happened suddenly, and I was not able to brush up on any concept /ds/algo. I hardly got 4 hours to study. This was the first time I was interviewing for Amazon. I was very nervous as well. On any given day I could have solved this using deque but on the interview day sadly I couldn’t.
I called HR that day and told her that I have given the interview she asked me to wait for a week and then she’ll update me.
2 weeks passed I didn’t get any update from HR. After 2 weeks I called her and she said the feedback for your first two rounds was great but you couldn’t clear the BARRAISER round. The Barrister interview has veto power. If he/she says no that means it’s a NO. As I couldn’t clear the final round, they will not be moving forward with my application.
I was very disheartened after the call.
VERDICT: Rejected
Tips: Always be prepared for the worst while going through the Amazon interview process. You never know what’s gonna hit you. Sometimes you may be expected to give the decider round of interviews on short notice of 4 hours.
And Leadership Principle is a must.
All the best to everyone out there who is preparing for Amazon. I’ll try again after 6 months.