TODO(you): Upvote my original post and other good (better?) answers on Quora. The following is my answer to the question "How should I prepare for my Google interview if I have 1 month left?"
With over ten years of programming experience and a CS degree, it took me about a month and a half of daily practice to get ready for the interview. “Ready,” for me, isambitiouslydefined as the ability to tackle almost any technical interview question in 30 minutes or less and reach an optimal solution. The following is based upon what I did to prepare—your mileage may vary.
Ingredients:
- About two years of solid coding experience
- Pencil and paper
- Cracking the Coding Interview (CTCI)
- Your favorite algorithms book—Introduction to Algorithms,The Algorithm Design Manual, andProgramming Pearlsare a few good choices. Might I suggest you go low tech and buy physical copies?
- Two or three hours a day
- Highly recommended: Whiteboard
- Highly recommended: CS degree
- Optional:MIT OpenCoursewareor another learning site
Directions:
1) Learn as much as you can about the Google interview process (days 1–2)
Just like an incomplete understanding of a technical question will ruin you in the actual interview, misinformation will derail your preparation leading up to it.I learned this the hard waywhen I failed at my first attempt after emphasizing brain teasers over studying algorithms and data structures.
Start with the source—check outgoogle.com/careersfor info on how Google hires. Then watchthis videofrom Google about what interviewers look for in the interview, and finally check outan example interviewfeaturing real Google engineers.
Once you have a solid foundation, I’d recommend following up by readingCTCI. Particularly focus on chapters 5 and 6 entitledBehavioral QuestionsandTechnical Questions.
By the time you finally read my short article about thesix things you absolutely need to doduring the actual interview, you should have a good grasp of what a well prepared candidate looks like.
2) Benchmark yourself (days 3–5)
Now that you know how prepared you need to be, figure out where you are right now. UseCTCIfor this. Take a couple of questions from each section and solve them using thesix steps I mentioned earlier. Keep track of how long it takes you to reach an optimal solution for each problem you solve.
If and only if you’ve solved the problem yourself, take a look at the accompanying solution to assess how you did. Did you reach the optimal solution or at least progress beyond the naive/brute force answer? How long did it take you? Was your code written in the fewest lines possible?
Do this for every section. When done, you can prioritize the sections that you didn’t do so well on up front in your practice regimen and leave the other sections for later. You should repeat this exercise just before your interview so that you know your weak spots going into the day of the interview.
3) Make a study list (days 3–5)
Using the data you acquired from the previous step, make a prioritized list of things you need to study. This list should include:
- Memorizing two good sorting algorithms andtheir Big-O
- Memorizing binary search
- Memorizing how to implement basic data structures such as hashmap, linked list, stack, queue, and trees (n-ary, trie, heap) andtheir Big-O complexities
- Memorizing graph traversal algorithms (BFS, DFS, and a shortest path algorithm like Dijkstra's)
- Memorizing powers of 2
- Practice bit manipulation exercises (working with bit maps, bit shifting)
- Object-Oriented Programming terminology (abstraction, inheritance, cohesion, coupling)
- Know the collections and math APIs for your given programming language
- Recursion, backtracking, and memoization
- Review principles of basic discrete mathematics and statistics
This is all covered inCTCIand your favorite algorithms book.Note:the point of the memorization is understanding! You will probably never be asked to write out an algorithm verbatim. Rather, you’ll be expected to know each well enough that you can use them creatively to solve a problem you’ve never seen.
4) Practice algorithms and data structures daily (days 6–30)
Pick a two or three items from your list and commit about two or three hours each day working on these things (e.g. 1 hr before work, lunch break, 1 hr after work). As you memorize things, test yourself by writing out an algorithm or data structure on paper or on a whiteboard. Write down the worst case Big-O time and space complexities for the algorithm when you’re done. Always check your work, always!
Now copy what you’ve written to your favorite IDE and compile. Take note of any compilation errors so that you can avoid them when you repeat the exercise again. You can and should also create unit tests to verify the correctness of your code.
Keep doing this until you can transcribe and compile your code without logical or syntactical errors.
5) Tackle as many programming questions as you can (days 16–30)
By now, you should have a pretty good handle on the skills you need to succeed on an interview question. Starting with CTCI, tackle every single programming problem you can, again usingthe six steps. Devote about half your study time to this while you spend the other half reviewing items from your study list.
If you’re doing well, you’ll probably start to run out of questions in the book. You can find tons more of real samples online from sites likeCareerCuporInterview Cake. Or, just use your favorite search engine. I know apretty good oneyou can use ;).
Practice a few times with another person, both with someone technicalandsomeone non-technical. Ask them if:
- You looked and sounded relaxed
- You looked like a disciplined problem solver
- You kept thinking out loud throughout the entire exercise
6) Relax and get some good sleep (day 30)
Congratulations! You’ve worked really hard. There’s nothing else you can do. Relax and get into your good place. You’ve made it this far. That means you either really enjoy coding or that you will stop at nothing to get that job at Google. I think you will genuinely enjoy your interview experience. Make sure to have fun! I look forward to seeing you in the meeting room.
