This is the crude stuff about how my interview at Amazon went, I did not want to bore my dear friends with it, but then I thought may be someone would find it useful. So this will be one among that few that's just there in my blog but not for my readers to read. This is for that tech crazy job aspiring people who would really find this useful as I found many such blogs useful for my preparations.
Amazon’s interview process is sure one of the toughest to crack,
especially since they come with a very specific list of skills. Amazon’s
interview process is intended to analyse one on the basis of a set of data
points and the cumulative of all data points are taken to find the final
result. It must also be noted that if one candidate fails to satisfy the
company’s requirement even on one data point he or she will be eliminated
instantly.
An Overview of Amazon's Interview process
Amazon looks for the following in any candidate
- Programming
skills
- Problem
solving skills
- Knowledge
of Data Structures and Algorithms
- Problem
identification skills
Amazon’s recruitment/placement process is divided mainly into two parts
- The
preliminary test
- The
technical interviews ( 3 – 4 interviews
in the span of a day)
The preliminary test contains both technical and aptitude based
questions and it also includes two programming questions that have to be coded
in an environment provided by amazon. The primary aim of the programing questions are
not to test your ability to produce outputs but the focus is on finding the
better answer or the faster easier logic.
The interviews purely
focuses on ones ability to solve problems and the depth of ones knowledge in
the field of data structures and algorithms. The more important thing is that
one should be able to code on paper as they will ask for complete working
programs and they wont provide you a compiler to test it on. Further care
should be taken when coding for the edge cases as all edge cases will be
explicitly tested on your code by them.
The Aptitude / Technical
Test
If ones dream of getting
into Amazon must come true then it is mandatory that this round be cleared and
clearing this is not very easy.
They ask around 20 wildly
assorted questions spanning everything in computer science fundamentals and a
few from aptitude section as well. One could always expect a few output
questions from c and cpp. The only trick is to be through with the
fundamentals. The list of questions and their topics I remember will be listed
at the end.
Programming Questions
The more crucial part of
the preliminary test is the coding section where you will be asked to code two rather simple programs ( simple in
reference to other programs that usually appear for coding contests or online
coding tests) within a time span of 45 mins. Though Amazon as such does not
explicitly specifies any restrictions with respect to the time and memory
conception of the code, they do evaluate by hand the optimality and efficiency
of the code to decide whom they should let in to the interviews.
Getting an output is not
the primary criteria for getting a safe passage into the interviews. Do take
extra care to make sure that a better solution is provided for each problem being
asked. One more thing that should be kept in mind is that though the environment
accepts your program if it provides the correct output for the provided
test case it may not get you to the next round. Make it a point to construct
your own test cases and test your code on that too. These should guarantee you
a safe passage to the next round.
Again the question that I
was asked and I remember will be provided at the end of the so called long
prose.
PS: By the way don’t think
about copying, they do use dif on the
codes.
The Interviews
I did have to go through a sum
total of about 6 hours of interview process before I was selected and it was
divided into 3 sessions. First a 45 minutes interview that tested me on problem
solving, next was an another 1 and a half hour interview on Data structures and
lastly a 3 hour 15 min interview on more advanced and tricky use of data
structures, algorithms and problem solving.
The first interview
included a warm welcome and two very straight forward questions, It only
included a basic understanding of data structures and some very crucial logic
to get past this one
The second one was a HR
interview and a technical interview rolled into one. The HR questions asked
were pretty basic and included questions like, what is your achievements and
why amazon so on and so forth. The one thing to be sure about is that you
should know your resume back and forth. They have asked me everything that was
there on that piece of paper. Again all questions I remember will be appended
to the document.
The third interview was the
toughest one of all, it was a gruelling three hour process and some tough
questions. There were two programming questions again one was really tough and
the next was relatively easier which was then followed by lots of direct
questions on data structures, more like rapid fire back to back questions
round.
Every time they do ask if we
have questions and its appreciated that one asks them questions and they do
like being asked questions about the company and how work happens in Amazon.
Tips and Tricks
· Learn to be able to deduce logic for solving a problem
and then convert the logic into code. Do follow the distinction between the
two. This helps achieve a generic approach to solving adhoc problems. I suggest
using of flowcharts to deduce this logic as it helps convert complex logic to
code very easily.( It aided me in coming out of the final interview in flying
colours).
· Try programming puzzles in sites like codechef and do
participate in coding contests. This helps in developing an appetite and aptitude for solving programing puzzles.
·
Do study data structures and algorithms very well, they
are absolutely necessary for Amazon and do practise such that you be able to
identify immediately what databases serves best when used to solve a particular problem.
The Questions
Preliminary
MCQ:
- Given a rectangle of given size what is the minimum no
of squares needed to exactly cover the rectangle.
- Identify a given algorithm.
- Given several pipelines their time costs and the delay
in starting each pipeline what is the time taken to execute a certain no of
instructions that are depended on each other.
- What is the maximum number of processors that can run
using 11 resources such that deadlock will not occur.
- Which of the following happens ( deadlock and
starvation), deduce for the given code.
- Several output questions.
- One question to identify the suitable characteristics
of a network to be used under specified circumstances.
- A question for speed distance and time.
Sorry that’s all I can
recall.
The two programming
questions are
- Given that amazon wants to recruit only one from a
group of n equally qualified candidates, they have decided to make them all
stand in a row and them ask the ones standing at odd places to go home,
repeatedly till one exists. Given n by standing at what position shall ensure a
sure recruitment by Amazon.
- Given a linked
list containing a sequence of characters, reorganise the string such that all
the vowels appear first and the consonants next and they be sorted in the order
they appeared.
Interview Round 1
- Given that amazon wants to recruit only one from a
group of n equally qualified candidates, they have decided to make them all
stand in a row and them ask the ones standing at odd places to go home, repeatedly till one exists. Given n by standing at what position shall ensure a
sure recruitment by Amazon. Assume that the list given is a linked list and all that you will have is
the pointer to the start of the linked list.
- Print the elements in a n x m matrix diagonally and
from bottom to top
Egs for a simple 3x3 matrix filled with number 1 - 9 print 7 , 4 8, 1 5 9, 2 6, 3
Interview Round 2
- Given a stack add the following feature without
changing any of the characteristics of the stack. getminelement() with unit
complexity, O(1).
- Everything in the resume round.
- What are my best achievements and why I consider it my
best achievement?
- What are my weaknesses and when and how has it affected
my productivity?
- What are my projects and explain in detail what I did?
- Explain how I managed my team and concentrated my teams
effort to achieve our aim.
Interview Round 3
- Given that the input is a binary tree connect all the
elements in the same level or depth using links.
- Given the stack what additional modification can you
bring to the stack such that you are able to check the presence of an element
in the stack.
- Direct questions on Hashing( predominantly )and other
data structures.
Additional Questions
- To swap adjacent elements of a linked list by modifying only the pointers. 1->2->3->4 becomes 2->1->4->3 and 1->2->3->4->5 becomes 2->1->4->3->5
- To sort the elements of a vector. Stable sort. The elements are sorted based on element%7. {1,2,3,4,5,6,7,14} becomes {7,14,1,2,3,4,5,6}
- To find number of sequences of the form 1...N such that each element differs from the previous by +1 or +2. N is the input. Bonus: Generate all possible sequences for given N.
- An array is given. Each element differs from the previous by +1 or -1. Best way to find the first occurrence of given number.
- Given an array of extremely huge size, find the sum of elements from ith index to jth index. There will be lots of queries even for a single array. So some sort of pre calculation is expected.
The first time I met her was in my first days
of college, in the most casual way, unnoticed and perturbing of each other’s
existence. The first time I talked to her was in the gleaming presence of
borosil glasses of the many million shapes and the vast variety of colourful
liquids that it contained. Under its silent and tinted rendering of a magnificent
evening was the first ever sounds greeted her in menial enquires. Then the
first share the first touch, the first embrace and the first kiss and above all
the first tear drop of love. 
