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Failing the coding interview

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Failing the coding interview

  1. 1. Cracking the coding interview Soohan Ahn Freakout Inc Failing
  2. 2. Survey
  3. 3. Resume Screening
  4. 4. 200+@ Applied
  5. 5. + Applied by the company website.. By the Linkedin...
  6. 6. Number of process to the next step? 10+@
  7. 7. Well.. Better than none
  8. 8. Check points ● Write a ‘hip’ resume. ○ Maybe, some recruiters would help you!
  9. 9. Check points ● Don’t waste time on the cover letter.
  10. 10. However... VISA WORK PERMIT
  11. 11. ● Citizen! Nationality. ● Or, Degree! ○ Funding…. Visa, Work permit
  12. 12. ● Japan, Singapore <<<< Australia, Canada <<<<<<< US Visa sponsorship difficulty (In my opinion..)
  13. 13. ● Possibility of relocation! ○ Indeed Tokyo -> Indeed US ○ Google Tokyo -> Google Palo Alto ○ Amazon Vancouver -> Amazon Seattle ○ etc.. Visa, Work permit
  14. 14. Online Coding Assesment
  15. 15. Invitement!
  16. 16. Online assesment platforms
  17. 17. Online assesment - 2018/01 ● Codility ○ https://www.codility.com/ ○ Failed….
  18. 18. Shocked… End of the world...
  19. 19. Silicon Valley - HBO
  20. 20. Practice, Practice, Practice!!!! ● Codeforces ○ http://codeforces.com/
  21. 21. Practice, Practice, Practice!!!!
  22. 22. Practice, Practice, Practice!!!! ● Atcoder ○ https://atcoder.jp/
  23. 23. Difficulty ● Atcoder ○ Beginner contest: A,B,C ○ Reguler contest: A,B ● Codeforces ○ Div2: A,B,C
  24. 24. Online assesment - 2018/8 ● Atcoder ○ Difficult.. ○ 2/4 (50%) is enough. ○ Passed!
  25. 25. Online assesment - 2018/08 ● Codility ○ Passed!
  26. 26. Online assesment - 2018/08 ● Hackerrank ○ Passed!
  27. 27. Online assesment - 2018/11 ● Hackerrank ○ Passed!
  28. 28. Project Assignments
  29. 29. Project assignment ● Implement simple project, and share it to the private repository.
  30. 30. Project assignment - 2018/11 ● A simple version of Imgur ● Floyd-warshall
  31. 31. Phone-Online interview
  32. 32. Online VS Phone - Onsite Interview Online Phone, Onsite Platform Programming platform Whiteboard, Text editor Space complexity Not so important.. It is important!!! Time complexity It matters.. It is important!!! Mission Shut up and write down the code. Shut up and you fail!
  33. 33. Online Interview - 2018/8 ● Casual tech talk. ○ Failed to review my resume well... ○ Failed.... ○ Resume review is IMPORTANT!!
  34. 34. Online Interview - 2018/09 ● Design a chatting app. ● Implement LRU Cache.
  35. 35. Online Interview - 2018/09
  36. 36. Practice, Practice, Practice!!!!
  37. 37. Practice, Practice, Practice!!!!
  38. 38. Practice, Practice, Practice!!!!
  39. 39. Practice, Practice, Practice!!!! ● Easy, Medium : Essential ● Hard: Popular problems. ○ LRU Cache
  40. 40. Online Interview - 2018/12 ● Implement a random number distributor. ○ Std::vector::push_back… ● Should study STL, little bit deeper!
  41. 41. Online Interview - 2018/12
  42. 42. STL ● Standard template library for C++. ● JAVA: Collection (?)
  43. 43. Essential STL classes ● std::vector ○ Kind of array. ○ Using reserve makes better performance. ○ vector::push_back : Constant time.
  44. 44. Essential STL classes ● std::vector ○ https://en.cppreference.com/w/cpp/container/vector
  45. 45. Essential STL classes ● std::unordered_(map / set) ○ Hashmap. ○ Unsorted.
  46. 46. Essential STL classes ● std::map / set ○ Sorted hashmap. ○ http://www.cplusplus.com/reference/map/map/
  47. 47. Essential STL classes ● std::priority_quque ● std::stack ● std::queue ● std::list ● std::pair ● std::sort
  48. 48. Online Interview - 2018/11 ● Simple algorithm questions.
  49. 49. Online Interview - 2018/12 ● C++ and low-level questions. ● Failed. + No notice.
  50. 50. Online Interview - 2018/12 ● Light tech talk. ● About an assignment.
  51. 51. Onsite Interview
  52. 52. Before jumping to the onsite interview..
  53. 53. Online Interview - 2018/09 ● Signed NDA… ● Problem was simple. ● Be careful at the simple problem! ○ Check requirements and the edge cases!
  54. 54. Online Interview - 2018/12 ● 30 min tech talk. ● 1 algorithm problem
  55. 55. Onsite Interview - 2018/10
  56. 56. Onsite Interview - 2018/10 https://www.ana.co.jp
  57. 57. Onsite Interview - 2018/10
  58. 58. Onsite Interview - 2018/10 ● Meal: $65/day ● Taxi: $100/day ● ETC: $45/day ○ Wifi router..
  59. 59. Onsite Interview - 2018/10 ● Signed NDA… ● 60min X 5 + 60min lunch ○ 4 Engineers ○ 1 Product manager
  60. 60. Onsite Interview - 2018/10 ● Each interview ○ 30 min behaviour. ○ 30 min coding interview
  61. 61. Onsite Interview - 2018/10
  62. 62. Onsite Interview - 2018/10
  63. 63. Onsite Interview - 2018/10 ● Lack of the experience ○ Panic ○ Design problems(OOP, System)
  64. 64. Practice, Practice, Practice!!!!
  65. 65. Practice, Practice, Practice!!!! ● Not only solving lots of problem. ● Review, and make it perfect. ● Also, solve RELATED problems.
  66. 66. Practice, Practice, Practice!!!!
  67. 67. Practice, Practice, Practice!!!!
  68. 68. ● Write the simple code! ○ Less than 30 lines. ○ Make logics black box by functions! ○ In tree problem, implement by recursion! ○ Check other people’s optimized code! Practice, Practice, Practice!!!!
  69. 69. Practice, Practice, Practice!!!! ● Peer mock interview platform! ○ I interview you, you interview me. ○ Not only interview prep, but English speaking!!
  70. 70. Onsite Interview - 2019/01 ● 3 tech interviews. ● Got follow up problems. Solved well.
  71. 71. Offer
  72. 72. Offer! But, declined..
  73. 73. Offer!
  74. 74. Excercises
  75. 75. LRU Cache ● https://leetcode.com/problems/lru-cache/
  76. 76. LRU Cache ● Hard to think about a implementation details during the interview.
  77. 77. LRU Cache ● Time complexity of std::list::erase?
  78. 78. LRU Cache ● Time complexity of std::list::erase? ○ https://en.cppreference.com/w/cpp/container/list/erase Constant O(last - first)
  79. 79. LRU Cache ● Deeper.. ○ Implement a list class including an erase method.
  80. 80. LRU Cache ● Implement a list class including an erase method. ○ Need to know about a list structure!!
  81. 81. Lowest Common Ancestor of binary tree ● https://leetcode.com/problems/lowest- common-ancestor-of-a-binary- tree/description/ ● Implement it recursively.
  82. 82. ● Implement it recursively. Lowest Common Ancestor of binary tree
  83. 83. ● Implement it recursively. Lowest Common Ancestor of binary tree Time complexity: O(n) Space complexity: O(1)
  84. 84. More problems ● 2sum ● Merge intervals ● Find the celebrity ● Valid parentheses
  85. 85. Wrap up
  86. 86. Wrapup ● Frustrating ● Tired ● Depressed ● Painful
  87. 87. Wrapup ● NOT FUCKING TALENTED. ● PRACTICE!
  88. 88. Wrapup ● Improvement! ● Offer
  89. 89. - Cao Hong (a.k.a 조홍) Ref: 三國志 曹操伝 (KOEI)
  90. 90. “Practice, Practice, Practice!!!!” - Soohan Ahn
  91. 91. Thanks!

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