Job Interview Tips

Here are
some hints and tips to help you prepare for success! Those who study tend to do
FAR better on their interviews!

**1) Plan ahead:
**The Google engineers who will be interviewing you have only limited

time set aside from their projects, so please reserve time in your

schedule, too! This also helps you relax and perform better at

interview. Please have a pen and paper handy in the case that you are

asked to write some things down.

The interviewer will be interested in your knowledge of computer

science principles (data structures, algorithms etc.) and how they can

be used in your solutions.

stated that you are an expert!), whiteboard coding questions, building

and developing complex algorithms and analyzing their performance

characteristics, logic problems, systems design and core computer

science principles - hash tables, stacks, arrays, etc. Computer

Science fundamentals are pre-requisite for all engineering roles at

Google, regardless of seniority, due to the complexities and global

scale of the projects you would end up participating in.

importantly, you'll need more information from the interviewer to

analyze & answer the question to its full extent.

* Its OK to question your interviewer.

* When asked to provide a solution, first define and frame the

problem as you see it.

* If you don't understand - ask for help or clarification.

* If you need to assume something - verbally check whether it is a correct assumption!

* Describe how you want to tackle solving each part of the question.

* Always let your interviewer know what you are thinking as he/she

will be as interested in your process of thought as your solution.

Also, if you're stuck, they may provide hints if they know what you're

doing.

* Finally, listen - don't miss a hint if your interviewer is trying to

assist you!

5) What is Google looking for?:

"We are not simply looking for engineers to solve the problems they

already know the answers to; we are interested in engineers who can

work out the answers to questions they had not come across before."

Interviewers will be looking at the approach to questions as much as

the answer -

* Does the candidate listen carefully and comprehend the question?

* Are the correct questions asked before proceeding? (important!)

* Is brute force used to solve a problem? (not good!)

* Are things assumed without first checking? (not good!)

* Are hints heard and heeded?

* Is the candidate slow to comprehend / solve problems? (not good!)

* Does the candidate enjoy finding multiple solutions before choosing

the best one?

* Are new ideas and methods of tackling a problem sought?

* Is the candidate inventive and flexible in their solutions and open

to new ideas?

* Can questioning move up to more complex problem solving?

Google is keen to see really high quality, efficient, clear code

without typing mistakes. Because all engineers (at every level)

collaborate throughout the Google code base, with an efficient code

review process, it's essential that every engineer works at the same

high standard.

7) Ask more questions!:

Make sure you have a decent understanding of Google as a business -

further than Google's main products - find out about what we do here:

http://www.google.com/corporate/ OR:

http://en.wikipedia.org/wiki/Google

At the end of the interview, most interviewers will ask you if you

have any questions about the company, work environment, their

experience, etc. Its clever to have some pre-prepared for each

interview, but don't worry too much if your mind goes blank.

If you have questions about the interview process, remuneration or

your performance, please direct these to your recruiter.

8) Further reading:

*To understand how Google's development teams work -

http://en.wikipedia.org/wiki/Agile_development

*To know more about Google's core projects -

http://labs.google.com/why-google.html

If you have not already read through Steve Yegge's technical prep

tips, please check out his blog -

http://steve-yegge.blogspot.com/2008/03/get-that-job-at-google.html

*Due to the size of the products you'll be building, its imperative

you're comfortable with big O notation, here's where to brush up -

http://en.wikipedia.org/wiki/Big_o_notation

9) Technical Preparation tips!:

The main areas software engineers should prepare to succeed at

interview at Google:

Algorithm Complexity: You need to know Big-O. If you struggle with

basic big-O complexity analysis, then you are almost guaranteed not to

get hired.

Sorting: Know how to sort. Don't do bubble-sort. You should know the

details of at least one n*log(n) sorting algorithm, preferably two

(say, quicksort and merge sort). Merge sort can be highly useful in

situations where quicksort is impractical, so take a look at it.

Hashtables: Arguably the single most important data structure known

to mankind. You absolutely should know how they work. Be able to

implement one using only arrays in your favorite language, in about

the space of one interview.

Trees: Know about trees; basic tree construction, traversal and

manipulation algorithms. Familiarize yourself with binary trees, n-ary

trees, and trie-trees. Be familiar with at least one type of balanced

binary tree, whether it's a red/black tree, a splay tree or an AVL

tree, and know how it's implemented. Understand tree traversal

algorithms: BFS and DFS, and know the difference between inorder,

postorder and preorder.

Graphs: Graphs are really important at Google. There are 3 basic ways

to represent a graph in memory (objects and pointers, matrix, and

adjacency list); familiarize yourself with each representation and its

pros & cons. You should know the basic graph traversal algorithms:

breadth-first search and depth-first search. Know their computational

complexity, their tradeoffs, and how to implement them in real code.

If you get a chance, try to study up on fancier algorithms, such as

Dijkstra and A*.

Other data structures: You should study up on as many other data

structures and algorithms as possible. You should especially know

about the most famous classes of NP-complete problems, such as

traveling salesman and the knapsack problem, and be able to recognize

them when an interviewer asks you them in disguise. Find out what

NP-complete means.

Mathematics: Some interviewers ask basic discrete math questions.

This is more prevalent at Google than at other companies because we

are surrounded by counting problems, probability problems, and other

Discrete Math 101 situations. Spend some time before the interview

refreshing your memory on (or teaching yourself) the essentials of

combinatorics and probability. You should be familiar with n-choose-k

problems and their ilk – the more the better.

Operating Systems: Know about processes, threads and concurrency

issues. Know about locks and mutexes and semaphores and monitors and

how they work. Know about deadlock and livelock and how to avoid them.

Know what resources a processes needs, and a thread needs, and how

context switching works, and how it's initiated by the operating

system and underlying hardware. Know a little about scheduling. The

world is rapidly moving towards multi-core, so know the fundamentals

of "modern" concurrency constructs.

Coding: You should know at least one programming language really

well, and it should preferably be C++ or Java. C# is OK too, since

it's pretty similar to Java. You will be expected to write some code

in at least some of your interviews. You will be expected to know a

fair amount of detail about your favorite programming language.

10)Sample Topics:

Coding

Sample topics: construct / traverse data structures, implement system

routines, distill large data sets to single values, transform one data

set to another.

Algorithm Design / Analysis

Sample topics: big-O analysis, sorting and hashing, handling obscenely

large amounts of data. Also see topics listed under 'Coding'.

System Design

Sample topics: features sets, interfaces, class hierarchies, designing

a system under certain constraints, simplicity and robustness,

tradeoffs.

Open-Ended Discussion

Sample topics: biggest challenges faced, best/worst designs seen,

performance analysis and optimization, testing, ideas for improving

existing products.

To practice for your interview you may want to visit the website

www.topcoder.com

If you launch the "Arena" widget and then go to the practice rooms

where you can play with the problems in the first/second division as a

warm up.

I know this was a lot to read, but I wanted you to be prepared.