1. Cracking the Technical Interview Cracking the Technical 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 120+ candidates

3. CareerCup Founded 2005 Largest source for technical interview questions (3000+ FREE questions) Services: Book Video 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. Evaluation (What They Say)

8. Big Company Evaluation (Actual) Experience

9. Big Company Eval = No Red Flags “Better to lose a good candidate than to hire a bad one.” “Better to lose a good candidate than to hire a bad one.”

10. Smaller Companies Interview process varies Care more about experience / personality Might ask to see “portfolio”

11. What do companies look for? Applying

12. What do companies look for? Project experience! Course work Open source Independent studies Weiss Tech House Know C++ or Java well Skills Passion Work Ethic

13. Resume Advice: One Page. Seriously. 3 Sections: Education, Employment, Projects List languages with experience level Pet Peeve: Save file with your name

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

15. Research the company / team Prepare questions: Genuine Questions Things you really want to know Insightful Questions Technical questions that show your CS knowledge Passion Questions Questions that show your tech passion Soft Prep – The Company / Team

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

17. 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

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

19. Data structures Algorithms Concepts What to study

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

21. Implementation Space vs Time Complexity Algorithms

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

23. Don’t practice on computer!

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

25. The Interview: Chit Chat Beginning + End of Interview What? Resume questions (hardest bug, etc) General questions Opportunity for you to ask questions Why? Get to know your personality / interests RELAXES you

26. The Interview: Chit Chat - 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.” Limited details (else too hard to follow) Ask good questions!

27. ituation ction esponse The Interview: Chit Chat - Tips S structure your responses A R

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

29. General Advice for Technical Questions Talk out loud – show us how you think! Good interviews = hard questions Don’t be nervous if you can’t solve something! You’re not done until they say you’re done.

30. 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++”

31. Standard Coding and Algorithms Question Type #1

32. 5 Steps #1 Standard Coding and Algorithms

33. Asking Questions What are the data types? How much data? What assumptions do you need? Who is the user? NOTE: Especially important at Microsoft. #1 Standard Coding and Algorithms

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

35. 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

36. Algorithm Generation Pattern Matching Write code to reverse the order of words in a sentence. Example: input: “iPad is an awful name” output: “name awful an is iPad” #1 Standard Coding and Algorithms

37. 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

38. Algorithm Generation Base Case & Build Design an algorithm to print all valid combinations of n pairs of parentheses. Example: input: n = 3 output: ( )( )( ), ( ) ( () ), ( () )(), ((())) #1 Standard Coding and Algorithms

39. 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

40. Poking Holes 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? #1 Standard Coding and Algorithms

41. 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 #1 Standard Coding and Algorithms

42. Testing Test your code! Extreme cases Check for user error Test general cases CAREFULLY FIX MISTAKES #1 Standard Coding and Algorithms

43. Object Oriented Design Question Type #2

44. OOD Steps #2 Object Oriented Design Clarifying Questions What are the core objects? What is the interaction (eg, methods)? Walk through uses. Have you missed anything? Are there any algorithms you need?

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

46. Restaurant OOD #2 Object Oriented Design 1. Clarifying Questions How many guests? Buffet or entrees? What meals does it serve?

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

48. Restaurant OOD #2 Object Oriented Design 3. Interaction Server assigned to Table by Host Guests order Meal from Menu via Server Oops! Forgot menu!

49. Restaurant OOD #2 Object Oriented Design 4. Walk Through Uses Party enters with Guest(s). Assigned to Table. Order items.

50. Restaurant OOD #2 Object Oriented Design 5. Algorithms How do you find a free table? How do you remove out-of-stock item from menu?

51. Large Scale System Design Question Type #3

52. Large Scale Steps #3 Large Scale System Design Simplify Develop algorithm for simple case Generalize What problems do you hit? Can you solve them?

53. Trivia Question Type #4

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

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

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

57. The Offer It’s always negotiable Helps if you have competing offer Don’t lie – companies know what competitors offer Is it really what you want? Money, career options, etc

58. My Red Flags: People who… … wrote code and didn’t test it … found mistakes and would make random fixes … jammed things messily into an existing data structure … didn’t consider the impact of their algorithms … were scared to try

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

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

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

62. Other Resources E-Book Video Mock Interviews Slides posted at CareerCup.com/slides www.CareerCup.com20% discount with code: [removed from online posting – email me to get it] I have removed the discount code from online posting because, well, things are Google-able and the code is intended for penn students. Please email gayle@careercup.com from your UPENN email address to get the code.