1. Cracking the Technical Interview Cracking the Coding Interview Gayle Laakmann Founder / CEO, CareerCup.com

2. My Background Penn BSE / MSE ‘05 in CS Ex-Engineer at Google, Microsoft and Apple + Offers from Amazon, IBM and others 3 Years on Google Hiring Committee Interviewed 150+ candidates

3. CareerCup Founded 2005 Largest source for technical interview questions (3000+ FREE questions) Services: Book (Cracking the Coding Interview) Video of interview Resume review Mock interviews

5. How are interviews structured? How are you evaluated? Process

6. Technical Interview Process Initial Screen (Phone / Campus) 4 - 5 on site interviews 10 min General 40 min Technical 10 min Closing Sometimes “blind” interview

7. Big Company Evaluation Experience Personality and… No Red Flags

8. What are red flags? Arrogance Communication Issues Arguing (too much) Dishonesty

9. Smaller Companies Tend to look for broader skills Care more about experience / personality Might ask to see “portfolio” but… It varies!

10. What do companies look for? Applying

11. What can you do? Get project experience! Course work Open source Independent studies Weiss Tech House Part-time job Start a business! Know C++ or Java well Good grades are nice – but not enough! Skills Passion Work Ethic Creativity Initiative

12. 3 Hallmarks of a Great Resume: Short and sweet One page – no more! Short bullets (1 – 2 lines). No paragraphs! Accomplishments, not responsibilities Quantify! Clean, Professional and Well Structured Projects section No spelling / grammar mistakes Nice resume format (don’t format via spaces!)

13. Why do you want to work here? What was your favorite project? Interview prep – SOFT SKILLS

14. Research the company / team Prepare questions (around 10) Know: What they do (duh) Specific products – what is good / bad What their hardest problems are Why you want to work there What value you can add (esp. if non-coding role) Soft Prep – The Company / Team

15. Create Preparation Grid for Projects + (maybe) Behavioral Grid Soft Prep – Yourself

16. Strengths vs. Weaknesses Mediocre answer: “it was hard because I had to learn new languages / technologies” Not just answering Q’s – show who you are! Soft Prep – Yourself

17. How do you prep for coding questions? What do you prep? Interview prep – Tech SKILLS

18. Study the basics: CLR algorithms book is great – but too complex for interviews Write code on paper Put away the compiler Look up sample interview questions Focus on the topics you’re struggling with How to study

19. How to implement When to use (pros / cons) Data Structures

20. Implementation Space vs Time Complexity Algorithms

21. Concepts Not just a concept – know how to code!

22. Don’t practice on computer!

23. What do companies look for? Interview – soft SKILLS

24. Communication Tips Be specific – not arrogant “Yeah, I did all the hard work for the team” “I implemented the file system, which was considered one of the hardest components.” Be concise and structured Nugget First S.A.R.: Situation, Action, Result

25. Lead with your “thesis” / nugget Nuggets grab the listener’s attention, and tell them where you’re going Q: What accomplishment are you most proud of? A: The time that I convinced the engineering school to switch to paperless time logs. Structure 1: Nugget First

26. ituation ction esult Structure 2: S.A.R. S What did you do? What should I care? A R

27. How do you tackle hard tech questions? Interview – tech SKILLS

28. Mastering the Technical Questions Ask Questions! Questions are more ambiguous than they appear Talk out loud Show us how you think Think critically Does your algorithm really work? What’s the space and time complexity? Code slowly and methodically It’s not a race Test your code You’re not done until they say you’re done!

29. Step 1: Ask Questions What are the data types? How much data? What assumptions do you need? Who is the user? NOTE: Especially important at Microsoft.

30. Step 2: Think Critically What’s space / time complexity? What if there’s lots of data? Does your design cause other issues? If there are other issues, did you make the right trade offs?

31. Step 3: Talk Out Loud Approach is more important than answer Talking out loud: Shows us how you think Lets the interviewer guide you Makes you not appear “stuck”

32. Step 4: Pseudo Code & Code Pseudo code first – but say that! Use data structures generously What are the right ones? Define your own = shows good style Don’t crowd your coding Start in the upper left corner of board, not bottom

33. Step 5: Testing Test your code! Extreme cases Check for user error Test general cases CAREFULLY FIX MISTAKES

34. RELAX! Interviews are supposed to be hard! Everyone makes mistakes. Everyone!

35. Question Types Standard Coding and Algorithms “Reverse a linked list” Object Oriented Design “Design a parking lot” Large System Design “Design a program to crawl the web” Trivia “What does a “vtable” refer to in C++”

36. Standard Coding and Algorithms Question Type #1

37. Algorithm Generation #1 Standard Coding and Algorithms OMG! I have no idea how to solve this problem!

38. Algorithm Generation Pattern Matching What problem is this similar to? Simplify / Generalize What if the data was a different type? Base Case & Build Can you do this just for element 1? 1 and 2? … Data Structure Brainstorm Go through all data structures – can they help? #1 Standard Coding and Algorithms

39. Algorithm Generation Pattern Matching Write code to reverse the order of words in a sentence. Example: input: “she ran to the store” output: “store the to ran she” #1 Standard Coding and Algorithms

40. Algorithm Generation Simplify / Generalize Write a program to remove the duplicate characters in a string without using any additional buffers. #1 Standard Coding and Algorithms

41. Algorithm Generation Base Case & Build Design an algorithm to print all subsets of a set (e.g., the power set) Example: input: {a, b, c} output: {{}, {a}, {b}, {c}, {a, b}, {a, c}, {b, c}, {a, b, c}} #1 Standard Coding and Algorithms

42. Algorithm Generation Data Structures Brainstorm Design an algorithm to figure out if someone has won a game of tic-tac-toe. Make it as fast as possible. #1 Standard Coding and Algorithms

43. Object Oriented Design Question Type #2

44. Core objects what are the core objects? Relationships what is their relationship to each other? Interactions how do they interact? Algorithms what are the tricky / interesting algorithms? OOD Steps (C.R.I.A.) #2 Object Oriented Design

45. OOD Example #2 Object Oriented Design Design the data structures for a restaurant

46. Restaurant OOD #2 Object Oriented Design 1. Core Objects Guest Party Server Table Meal Order

47. Restaurant OOD #2 Object Oriented Design 2. Relationships Each party has many guests. Each guest has one party. (“One to many”)

48. Restaurant OOD #2 Object Oriented Design 3. Interactions Party enters with Guest(s). Host assigns Party to Table.

49. Restaurant OOD #2 Object Oriented Design 4. Algorithms How do you find a free table?

50. Large Scale System Design Question Type #3

51. Large Scale Steps #3 Large Scale System Design Simplify Generalize Generalize to more data:find & solve problems Solve for simple case (less data)

52. Trivia Question Type #4

53. Trivia #4 Trivia Hopefully you know the answer! Practice more  Else… Admit that you don’t know Try to derive the answer

54. (eg, things that wouldn’t fit in elsewhere) FINAL THOUGHTS

55. The Interview: Ending It Smile, be positive If you think you bombed, don’t worry Follow up with your recruiters (sometimes they forget)

56. The Offer It’s always negotiable Helps if you have competing offer Don’t lie – companies know what competitors offer Negotiate on multiple factors (salary, signing bonus, stock, etc) Is it really what you want? Money, career options, etc

57. My Red Flags: People who… … didn’t test their code … found mistakes and would make random fixes … messy code (lack of data structures / redundant code) … didn’t consider the impact of their algorithms … were scared to try

58. Take Aways – Getting Ready Get Project Experience Show project experience on resume S. A. R. (Situation Action Result) Prepare Project / Behavioral Grids

59. Technical Interview Prep Things to know (data structures, algorithms, concepts) Simple  Know Implementation Complex  Know Concepts Practice interview questions!

60. At The Interview Be nice RELAX! Interviews are supposed to be hard Approaches Pattern Matching Simplify / Generalize Base Case & Build Data Structure Brainstorm

61. Other Resources Book (sold today - $20) Interview video Mock Interviews Resume Review Slides posted at CareerCup.com/slides #1 book for interviewing on Amazon! PS: CareerCup is hiring a part-time dev! (remember that part about needing coding experience?) If you know Ruby on Rails (or even if you don’t), contact gayle@careercup.com.