Amazon ACMS Experience

Hey Everyone! Amazon visited our campus for ACMS selection. I am sharing
my experience of entire journey here.
ROUND 1: Everyone who satisfied the required cgpa (probably 7) criteria was
allowed to sit for this round. There were three coding questions to be
completed in 1.5 hrs.
1. Arrays and Strings
2. Linked list — A linked list was given : 1->1->1->2->2->3->
Required Output: 1->3->2->2->3 (finds the occurrence for each element in an
unsorted list and printing it next to the element is frequency is greater than
1)
3. Linked List
ROUND 2: Shortlisted students received a mail from Amazon with another test
link of duration of 1.5 hrs.
The test had two coding questions and 30 MCQs. MCQs were based on OOPS
concepts, DSA, DBMS, OS and networking, Pointers in C++: concepts of pointer
to a pointer, function pass by values versus pass by reference, expected
output.
The selected students received a mail after 3–4 weeks. Mentorship was started
where three people were assigned a mentor, SDE in Amazon who guided us
throughout. There were 4–5 technical sessions where we were taught
different topics like OOPS, Data structures, functional programming, DBMS,
Design patterns, scalable services, web hosting, database clustering, NoSQL
etc..
Along with the technical sessions, assignments were given each week. A
project was also assigned to us. Based on assignments and project, we were
shortlisted for interviews.
ROUND 3: INTERVIEWS
I had two interviews on same day.
First Interview:
1. I was asked about a puzzle. You can refer the link below to know exact

problem statement.
https://www.geeksforgeeks.org/puzzle-two-robot-parachute-line/
2. Second question was easy.. it was similar to trapping rain water
https://www.geeksforgeeks.org/trapping-rain-water/
Second Interview:
1. I was asked about my mentorship and projects.
2. He asked me questions about hashmap in detail.. collision handling,
hashing, hash code etc.. He covered almost every topic related to hashing and
hashmap in depth.
3. LRU Cache
4. Questions related to graphs and trees in depth.
Time complexity and space complexity for each question was asked.
After around 3–4 weeks, I got the mail of selection along with 3 other students
from my college.
TIPS FOR PREPARATION
I practiced for about 5–6 months . Initially I practiced topic wise , later when I
was confident enough I started practicing company wise ( mainly for those
companies which visited our campus). Also I made it a habit to read atleast
one interview experience from gfg daily.
TIPS FOR INTERVIEW
1. Think out loud. Interviewer is more interested in knowing your thought
process than the exact solution. So, speak whatever you are thinking while
creating a solution.
2. Don’t give the most optimised solution directly even if you know, tell the
brute force solution first and then optimise the solution.. (my mentor gave me
this tip since he had also interviewed many candidates and rejected few who
acted too smart because he thought they are more of textbook geeks)
3. Ask the interviewer before starting to write the solution
4. Explain your approach first using examples and walk the interviewer throughout the solution. This creates an impression of clarity.
5. Interviewers drop hint whenever you are going in wrong path during
interview, try to form your solution around that hint.