Question

How long does it take to master algorithms and data structures to get a job at Amazon as SDE?

Answer 1

It depends on how much depth you already have and where you are at your preparation. I have been lucky to get offers from Amazon. Microsoft, Adobe just this year. Here is my suggested plan :

a) Spend enough time on data structure and algorithms.

This is the number one thing for all kinds of software engineer interviews. Make sure you are very familiar with those basic stuffs like binary tree, linked list, sorting algorithms etc. and also be fast at estimating efficiency of your code because most of the interviewers will ask time/space complexity of your code.

• Revise your knowledge of data structures.
• Pay special attention to Stacks, Queues, Heaps, Hash Maps and Trees.
• Go through the standard algorithmic paradigms (Greedy Algorithms, Dynamic Programming, Divide and Conquer, etc).
• Solve the related assignments and coursework

2–2.5 months should be enough to build the appropriate depth.

b) Practicing writing code on paper or whiteboard.

Online or onsite interviews with these companies require you to write solid code on online doc, paper, whiteboard etc. It might seem easy at first glance, but once you try it, you'll miss your favorite text editor or IDE so much! There's no indentation, syntax highlight and auto completion. I'd suggest you at least write some codes on paper to get you familiar with it.

1–1.5 months of coding on paper or whiteboard should give you enough speed and clarity on how to approach the coding part.

c) Practice with real interview questions for Amazon.

Solve real interview questions from companies that you are targeting, which in this case is Amazon. LeetCode is a very good resource for that.

1–1.5 months of solving real interview questions should cover famous patterns which can be asked again.

d) Mock Interviews.

It's a great experience for you to practice in a way where you can't fail. You can do this with your friends and interview them back.

I also got my mock interview from ExpertMitra whose interviewers are working at Google, Facebook etc. and gave me tons of feedback.

Overall 4–6 months would be decent to crack interviews at Amazon but of-course it depends a lot on the focus.

Answer 2

I was working with TCS for 2.5 years. So if you are a fresher you might be able to crack it in lesser time.

Here is my Experience,

I started my preparation on Jan 10′th of 2019. I did not do much coding in college as i was from a circuit branch. I picked Python in the beginning, as it gave me the felxibility to just think about the logic and not that much about the syntax.

It took a months time to get myself comfortable with loops, variables, scope, storage classes, primitive data types, condition based branching and some basic problems about array’s and strings .

Then i took time to get myself used to Data structures like Linked list, hash map, Binary Tree’s, BST, DP, Backtracking, Greedy Algorithms, Heaps .

All these topics are complex and a lot of times you would feel dumb and useless when you see a new question. It took 6 months for me to not feel scared when i see a new question and see the patterns for these questions. So It was August.

Then i started leetcode grinding, solved problems, everyday. Daily one problem in the morning before i went to work , another problem after i come home. I could see myself getting better at these problems, and i gained confidence every day. I also got myself used to some basic CS fundamentals like Computer Networks, OS and DBMS and this took up two more months . So it came up to November.

And I vividly remember DEC 4 there was a Amazon SDE off campus drive which happened and i had 6 rounds ( 1 online test , followed by 4 rounds, 1 bar raiser round). I remember Acing every question and i was finally told that i am hired after the bar raiser round. I was in tears of joy, because it took a year’s effort for me. Again I was working and i learn things slowly. You might be able to complete it earlier.

There are some paid resources that would help you fast track the learning. But if you learn it the hard way, then you won’t forget it and that will be shown in the interview .

Try practicing problems in white board as you go along.

Note down why your approach did not work and note down why the right approach is working.

Revise everyday . You will be bogged down with information everyday so it is always good to make notes.

Thanks.