Longhorn PHP 2021 - Passing the Technical Interview Workshop

Transcript

1. passing the
   Technical
   Interview
   🛠 workshop
   

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2. Who is this guy?
   Ben Edmunds
   Open Source
   Author
   PHP Town Hall Podcast
   More Than Code Podcast
   Sr Staff Eng @ Wayfair
   

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3. Will Cover
   Technical interview process
   from Phone Screen to Offer
   

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4. Won’t Cover
   Everything before the
   
   Phone Screen
   

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6. My Last
   Job Search
   

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7. Your Next
   Job Search
   

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8. Prep
   

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10. 1

    Phone 

    Screen
    2

    Manager 

    Screen
    3

    Coding
    Test
    4
    Onsite
    Evals
    

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11. Stages
    0. Reach Out
    • Accepted application
    
    • Communication from
    Recruiter
    

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12. 1

    Phone 

    Screen
    2

    Manager 

    Screen
    3

    Coding
    Test
    4
    Onsite
    Evals
    

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13. Stages
    1. Phone Screen
    • High level
    
    • Why are you looking
    
    • What are you looking for
    
    • Pitch on company/role
    

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15. Stages
    1. Phone Screen
    • Why
    
    • What
    PREP
    

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16. Stages
    1. Phone Screen
    • Structure of teams
    
    • Favorite projects
    
    PREP
    

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17. Stages
    1. Phone Screen
    • $
    PREP
    

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19. 1

    Phone 

    Screen
    2

    Manager 

    Screen
    3

    Coding
    Test
    4
    Onsite
    Evals
    

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20. Stages
    • High level but deeper tech
    
    • Experience with specific
    technologies
    
    • Pitch on Company/Role
    2. Manager Screen
    

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22. Stages
    • Hard Problems
    
    • Best Projects
    
    • Failures
    
    • Technologies
    2. Manager Screen
    PREP
    

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24. 1

    Phone 

    Screen
    2

    Manager 

    Screen
    3

    Coding
    Test
    4
    Onsite
    Evals
    

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25. Stages
    3. Coding Test
    • Take Home
    
    • or
    
    • Online Platform
    

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26. Stages
    3. Coding Test - Take Home
    • Small project
    
    • Designing architecture
    
    • Designing APIs
    
    • Solving algorithms
    

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27. Stages
    3. Coding Test - Online
    • Small problem(s)
    
    • Algorithmic problem
    
    • Time complexity
    
    • Space complexity
    

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29. Stages
    3. Coding Test
    • Lite version of Coding and
    Sys Design on-site evals
    
    • Real world experience
    PREP
    

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30. Stages
    3. Coding Test
    • Sys Design & Architecture
    
    • Based on role 

    interviewing for
    PREP
    

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31. Stages
    3. Coding Test
    • APIs
    
    • REST
    
    • GraphQL
    
    • RPC
    PREP
    

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32. Stages
    3. Coding Test
    • Data Structures
    
    • Array, Stack, Queue, 

    BT, BST, Hash Table
    PREP
    

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33. Stages
    3. Coding Test
    • Algos
    
    • Common Techniques
    PREP
    

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34. Stages
    3. Coding Test
    • Algos
    
    • Pattern Matching
    PREP
    

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35. Stages
    3. Coding Test
    • Algos
    
    • Common Problems
    PREP
    + FizzBuzz, 8
    Queens, Boggle,
    Subset Sum, etc
    

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36. Stages
    3. Coding Test
    • Algos
    
    • Improvements
    PREP
    

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37. Stages
    3. Coding Test
    • Sorting
    
    • Bubble Sort
    
    • Quick Sort
    
    • Merge Sort
    PREP
    

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38. Stages
    3. Coding Test
    • Fill knowledge gaps
    PREP
    

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39. Stages
    3. Coding Test
    • PRACTICE
    PREP
    

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40. Time & Space
    Complexity
    

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41. Complexity
    Time Complexity
    
    Space Complexity
    
    images: https://blog.devmountain.com/what-you-should-know-about-data-structures
    

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42. Complexity
    Big O notation
    
    images:https://www.geeksforgeeks.org/analysis-algorithms-big-o-analysis/
    

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43. Complexity
    O(1)
    $input = [1,2,3,4,5];
    return $input[3];
    

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44. Complexity
    O(log N)
    for ($i=0; $i<=count($input); $i*=2) {}
    

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45. Complexity
    O(N)
    for ($i=0; $i<=count($input); $i++) {}
    

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46. Complexity
    O(N log N)
    for ($i=0; $i<=count($input); $i++) {
    for ($j=0; $j<=count($input); $j*=2) {}
    }
    

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47. Complexity
    O(N2)
    for ($i=0; $i<=count($input); $i++) {
    for ($j=0; $j<=count($input); $j++) {}
    }
    

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48. Complexity
    O(N!)
    function factorial($n) {
    $factorial = 1;
    for ($i = 1; $i <= $n; $i++){
    $factorial = $factorial * $i;
    }
    return $factorial;
    }
    for ($i = 0; $i <= factorial(8); $i++) { }
    

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49. Data
    Structures
    

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50. Data Structures
    Array
    
    Stack
    
    Queue
    
    Linked List
    
    Tree
    
    Graph
    
    Hash Table
    
    Linear Non-linear
    

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51. Data Structures
    Array
    
    Stack
    
    Queue
    
    Linked List
    
    Linear Non-linear
    Tree
    
    Graph
    
    Hash Table
    
    

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52. Data Structures
    array
    
    images: https://blog.devmountain.com/what-you-should-know-about-data-structures
    

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53. Data Structures
    $array = ['Item1', 'Item2'];
    $array[0] => Item1
    

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54. Data Structures
    $array = [
    ['Item1-1', 'Item1-2'],
    ['Item2-1', 'Item2-2'],
    ];
    $array[0][1] => Item1-2
    

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55. Data Structures
    $array = [
    'namedIndex' => 'value'
    ];
    $array['namedIndex'] => value
    

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56. Data Structures
    stack
    
    images: https://blog.devmountain.com/what-you-should-know-about-data-structures
    

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57. Data Structures
    $stack = [0, 1, 2];
    array_pop($stack) => 2
    var_dump($stack) => [0, 1]
    

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58. Data Structures
    public isEmpty() : bool
    public pop() : mixed
    public push(mixed $value) : void
    

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59. Data Structures
    $stack = new Stack([0, 1, 2]);
    $stack->pop() => 2
    var_dump($stack) => [0, 1]
    

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60. Data Structures
    $stack = new Stack([0, 1]);
    $stack->push() => 3
    var_dump($stack) => [3, 0, 1]
    

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61. Data Structures
    queue
    
    images: https://blog.devmountain.com/what-you-should-know-about-data-structures
    

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62. Data Structures
    $queue = [0, 1, 2];
    array_pop_first($queue) => 0
    var_dump($queue) => [1, 2]
    

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63. Data Structures
    public isEmpty() : bool
    public pop() : mixed
    public push(mixed $value) : void
    

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64. Data Structures
    public isEmpty() : bool
    public dequeue() : mixed
    public enqueue(mixed $value) : void
    

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65. Data Structures
    $queue = new Queue([0, 1, 2]);
    $queue->pop() => 0
    var_dump($queue) => [1, 2]
    

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66. Data Structures
    $queue = new Queue([1, 2]);
    $queue->push() => 3
    var_dump($queue) => [1, 2, 3]
    

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67. Data Structures
    linked list
    
    images: https://blog.devmountain.com/what-you-should-know-about-data-structures
    

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68. Data Structures
    doubly linked list
    
    images: https://blog.devmountain.com/what-you-should-know-about-data-structures
    

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69. Data Structures
    $l = new SplDoublyLinkedList;
    $l->push('a');
    $l->push('b');
    $l->push('c');
    for ($l->rewind(); $l->valid(); $l->next()) {
    echo $l->current() . ', ';
    }
    => a, b, c
    

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70. Data Structures
    $l = new SplDoublyLinkedList;
    $l->push('a');
    $l->push('b');
    $l->push('c');
    $list->rewind();
    echo $list->current() . ', ';
    $list->next();
    echo $list->current() . ', ';
    $list->prev();
    echo $list->current();
    = > a, b, a
    

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71. Data Structures
    hash table
    
    images: https://blog.devmountain.com/what-you-should-know-about-data-structures
    

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72. Data Structures
    $hashMap = [
    sha1('first') => 1,
    sha1('second') => 2
    ];
    $hashMap[sha1('first')] => 1
    

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73. Data Structures
    $hashMap = [];
    for ($i=1; $i<=10; $i++){
    $hash = $i % 3;
    $hashMap[$hash] =
    isset($hashMap[$hash]) ?
    $hashMap[$hash] + $i : $i;
    }
    $hashMap[0] => 18
    

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74. Data Structures
    graph
    
    images: https://blog.devmountain.com/what-you-should-know-about-data-structures
    

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75. Data Structures
    graph
    
    images: https://blog.devmountain.com/what-you-should-know-about-data-structures
    

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76. Data Structures
    graph
    
    images: https://blog.devmountain.com/what-you-should-know-about-data-structures
    follow edges
    
    add to Queue
    
    process queue
    Breadth First
    Traversal
    

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77. Data Structures
    https://www.tutorialspoint.com/data_structures_algorithms/breadth_first_traversal.htm
    

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78. Data Structures
    graph
    
    images: https://blog.devmountain.com/what-you-should-know-about-data-structures
    follow edges
    
    add to Stack
    
    process stack
    Depth First
    Traversal
    

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79. Data Structures
    https://www.tutorialspoint.com/data_structures_algorithms/breadth_first_traversal.htm
    

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80. Data Structures
    tree
    
    images: https://blog.devmountain.com/what-you-should-know-about-data-structures
    

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81. Data Structures
    binary search tree
    (BST)
    
    https://delboy1978uk.wordpress.com/2018/02/06/binary-search-trees-in-php/
    

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82. Data Structures
    binary search tree
    (BST)
    
    23?
    https://delboy1978uk.wordpress.com/2018/02/06/binary-search-trees-in-php/
    

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83. Data Structures
    binary search tree
    (BST)
    
    20?
    null
    https://delboy1978uk.wordpress.com/2018/02/06/binary-search-trees-in-php/
    

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84. Data Structures
    binary search tree
    (BST)
    
    Breadth First
    Traversal
    https://delboy1978uk.wordpress.com/2018/02/06/binary-search-trees-in-php/
    5,2,11,1,4,
    7,23,16,34
    

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85. Data Structures
    binary search tree
    (BST)
    
    Depth First
    Traversal
    https://delboy1978uk.wordpress.com/2018/02/06/binary-search-trees-in-php/
    5, 2, 1, 4,
    11, 7, 23,
    16, 34
    

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86. Data Structures
    class Node
    {
    public $left, $right, $data;
    function __construct($data) {
    $this->data = $data;
    }
    }
    

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87. Data Structures
    class BST
    {
    public $rootNode;
    public function __construct($data=null)
    {
    if ($data !== null) {
    $this->rootNode = new Node($data);
    }
    }
    

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88. Data Structures
    public function search($data)
    {
    $node = $this->rootNode;
    while($node) {
    if ($data < $node->data) {
    $node = $node->left;
    } else if ($data > $node->data) {
    $node = $node->right;
    } else {
    break;
    }
    }
    return $node;
    }
    

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89. Data Structures
    trees IRL
    
    https://en.wikipedia.org/wiki/Radix_tree
    

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90. Data Structures
    https://en.wikipedia.org/wiki/Radix_tree
    

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91. Algorithms
    

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92. Algorithms
    Techniques
    
    

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93. Algorithms
    techniques
    brute force
    
    

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94. Algorithms
    techniques
    divide and conquer
    
    

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95. Algorithms
    techniques
    dynamic
    
    

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96. Algorithms
    techniques
    greedy
    
    

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97. Algorithms
    techniques
    recursive
    
    

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98. Algorithms
    techniques
    backtracking
    
    

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99. Algorithms
    Sorting
    
    

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100. Algorithms
     quicksort
     https://en.wikipedia.org/wiki/Quicksort
     

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101. Algorithms
     quicksort
     https://en.wikipedia.org/wiki/Quicksort
     O(n log n)
     

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102. Algorithms
     merge sort
     https://en.wikipedia.org/wiki/Quicksort
     

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103. Algorithms
     merge sort
     https://en.wikipedia.org/wiki/Quicksort
     O(n log n)
     

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104. Algorithms
     Examples
     
     

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105. Algorithms
     fizz buzz
     Write a program that prints the numbers from 1 to 100
     and for multiples of ‘3’ print “Fizz” instead of the
     number and for the multiples of ‘5’ print “Buzz”.
     
     

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106. Algorithms
     for ($i=1; $i<=100; $i++) {
     if ($i%3 === 0) {
     echo 'Fizz';
     }
     else if ($i%5 === 0) {
     echo 'Buzz';
     }
     else {
     echo $i;
     }
     }
     

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107. Algorithms
     time complexity
     O(n)
     
     https://en.wikipedia.org/wiki/Eight_queens_puzzle
     

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108. Algorithms
     single number
     Given a non-empty array of integers, every
     element appears twice except for one.
     
     Find that single one.
     

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109. Algorithms
     $input = [4, 1, 2, 1, 2];
     $noDups = [];
     foreach ($input as $value) {
     $k = array_search($value, $noDups);
     if ($k === false) {
     $noDups[] = $value;
     }
     else {
     unset($noDups[$k]);
     }
     }
     echo $noDups[0];
     

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110. Algorithms
     $input = [4, 1, 2, 1, 2];
     $noDups = [];
     foreach ($input as $value) {
     $k = array_search($value, $noDups);
     if ($k === false) {
     $noDups[] = $value;
     }
     else {
     unset($noDups[$k]);
     }
     }
     echo $noDups[0];
     

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111. Algorithms
     $input = [4, 1, 2, 1, 2];
     $noDups = [];
     foreach ($input as $value) {
     $k = array_search($value, $noDups);
     if ($k === false) {
     $noDups[] = $value;
     }
     else {
     unset($noDups[$k]);
     }
     }
     echo $noDups[0];
     

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112. Algorithms
     $input = [4, 1, 2, 1, 2];
     $noDups = [];
     foreach ($input as $value) {
     $k = array_search($value, $noDups);
     if ($k === false) {
     $noDups[] = $value;
     }
     else {
     unset($noDups[$k]);
     }
     }
     echo $noDups[0];
     

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113. Algorithms
     $input = [4, 1, 2, 1, 2];
     $noDups = [];
     foreach ($input as $value) {
     $k = array_search($value, $noDups);
     if ($k === false) {
     $noDups[] = $value;
     }
     else {
     unset($noDups[$k]);
     }
     }
     echo $noDups[0];
     

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114. Algorithms
     time complexity
     O(n2)
     
     https://en.wikipedia.org/wiki/Eight_queens_puzzle
     

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115. Algorithms
     $input = [4, 1, 2, 1, 2];
     $hashmap = [];
     foreach ($input as $v) {
     $hashmap[$v] = isset($hashmap[$v]) ?
     $hashmap[$v]+1 : 1;
     }
     foreach ($hashmap as $k => $count) {
     if ($count === 1) {
     echo $k;
     break;
     }
     }
     

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116. Algorithms
     $input = [4, 1, 2, 1, 2];
     $hashmap = [];
     foreach ($input as $v) {
     $hashmap[$v] = isset($hashmap[$v]) ?
     $hashmap[$v]+1 : 1;
     }
     foreach ($hashmap as $k => $count) {
     if ($count === 1) {
     echo $k;
     break;
     }
     }
     

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117. Algorithms
     $input = [4, 1, 2, 1, 2];
     $hashmap = [];
     foreach ($input as $v) {
     $hashmap[$v] = isset($hashmap[$v]) ?
     $hashmap[$v]+1 : 1;
     }
     foreach ($hashmap as $k => $count) {
     if ($count === 1) {
     echo $k;
     break;
     }
     }
     

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118. Algorithms
     $hashmap = array(3) {
     [4]=>
     int(1)
     [1]=>
     int(2)
     [2]=>
     int(2)
     }
     

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119. Algorithms
     $input = [4, 1, 2, 1, 2];
     $hashmap = [];
     foreach ($input as $v) {
     $hashmap[$v] = isset($hashmap[$v]) ?
     $hashmap[$v]+1 : 1;
     }
     foreach ($hashmap as $k => $count) {
     if ($count === 1) {
     echo $k;
     break;
     }
     }
     

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120. Algorithms
     $input = [4, 1, 2, 1, 2];
     $hashmap = [];
     foreach ($input as $v) {
     $hashmap[$v] = isset($hashmap[$v]) ?
     $hashmap[$v]+1 : 1;
     }
     foreach ($hashmap as $k => $count) {
     if ($count === 1) {
     echo $k;
     break;
     }
     }
     

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121. Algorithms
     time complexity
     O(n)
     
     

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122. Algorithms
     8 queens
     Place eight queens on an 8×8 chessboard so that no
     two queens threaten each other; thus, a solution
     requires that no two queens share the same row,
     column, or diagonal.
     

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123. Algorithms
     8 queens
     https://en.wikipedia.org/wiki/Eight_queens_puzzle
     

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124. Algorithms
     8 queens
     https://en.wikipedia.org/wiki/Eight_queens_puzzle
     

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125. Algorithms
     8 queens
     https://en.wikipedia.org/wiki/Eight_queens_puzzle
     

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126. Algorithms
     8 queens
     https://en.wikipedia.org/wiki/Eight_queens_puzzle
     

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127. Algorithms
     8 queens
     https://en.wikipedia.org/wiki/Eight_queens_puzzle
     

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128. Algorithms
     8 queens
     https://en.wikipedia.org/wiki/Eight_queens_puzzle
     

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129. Algorithms
     8 queens
     https://en.wikipedia.org/wiki/Eight_queens_puzzle
     

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130. Algorithms
     8 queens
     https://en.wikipedia.org/wiki/Eight_queens_puzzle
     

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131. Algorithms
     8 queens
     https://en.wikipedia.org/wiki/Eight_queens_puzzle
     

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132. Algorithms
     8 queens
     https://en.wikipedia.org/wiki/Eight_queens_puzzle
     

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133. Algorithms
     8 queens
     https://en.wikipedia.org/wiki/Eight_queens_puzzle
     

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134. Algorithms
     8 queens
     https://en.wikipedia.org/wiki/Eight_queens_puzzle
     

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135. Algorithms
     public function run() : bool
     {
     // 8 to the power of 8 =
     // 16,777,216 possible board configurations
     $board = $this->generateBoard($hash);
     if (!$this->hasCollisions($board)) {
     return true;
     }
     $this->run($hash-1);
     }
     

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136. Algorithms
     time complexity
     Brute Force = O(nn)
     
     https://en.wikipedia.org/wiki/Eight_queens_puzzle
     

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137. Algorithms
     https://en.wikipedia.org/wiki/Eight_queens_puzzle
     

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138. Algorithms
     8 queens
     https://en.wikipedia.org/wiki/Eight_queens_puzzle
     

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139. Algorithms
     8 queens
     https://en.wikipedia.org/wiki/Eight_queens_puzzle
     

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140. Algorithms
     8 queens
     https://en.wikipedia.org/wiki/Eight_queens_puzzle
     

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141. Algorithms
     8 queens
     https://en.wikipedia.org/wiki/Eight_queens_puzzle
     

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142. Algorithms
     8 queens
     https://en.wikipedia.org/wiki/Eight_queens_puzzle
     

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143. Algorithms
     8 queens
     https://en.wikipedia.org/wiki/Eight_queens_puzzle
     

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144. Algorithms
     interface SolverInterface
     {
     public function getBoard() : array;
     public function format() : string;
     public function hasCollision(int $row, int $col) : bool;
     public function run(int $col) : bool;
     }
     class NQueensSolver implements SolverInterface {}
     

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145. Algorithms
     $solver = new NQueensSolver(8);
     $solver->run();
     $expectedBoard = [
     [1, 0, 0, 0, 0, 0, 0, 0],
     [0, 0, 0, 0, 0, 0, 1, 0],
     [0, 0, 0, 0, 1, 0, 0, 0],
     [0, 0, 0, 0, 0, 0, 0, 1],
     [0, 1, 0, 0, 0, 0, 0, 0],
     [0, 0, 0, 1, 0, 0, 0, 0],
     [0, 0, 0, 0, 0, 1, 0, 0],
     [0, 0, 1, 0, 0, 0, 0, 0]
     ];
     echo 'Tests ' .
     ($solver->getBoard() === $expectedBoard ?
     'passed 🎉' : 'failed 🚨');
     

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146. Algorithms
     public function __construct($n=8)
     {
     $this->n = $n;
     $this->board = array_fill(
     0, $n, array_fill(0, $n, 0)
     );
     }
     

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147. Algorithms
     $this->board = [
     [0, 0, 0, 0, 0, 0, 0, 0],
     [0, 0, 0, 0, 0, 0, 0, 0],
     [0, 0, 0, 0, 0, 0, 0, 0],
     [0, 0, 0, 0, 0, 0, 0, 0],
     [0, 0, 0, 0, 0, 0, 0, 0],
     [0, 0, 0, 0, 0, 0, 0, 0],
     [0, 0, 0, 0, 0, 0, 0, 0],
     [0, 0, 0, 0, 0, 0, 0, 0]
     ];
     

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148. Algorithms
     public function getBoard() : array
     {
     return $this->board;
     }
     

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149. Algorithms
     public function run($col=0) : bool
     {
     // return true if we've iterated over the whole board
     if ($col >= $this->n) {
     return true;
     }
     // iterate over the rows
     for ($row = 0; $row < $this->n; ++$row) {
     if (!$this->hasCollision($row, $col)) {
     // place a queen
     $this->board[$row][$col] = 1;
     // check the next column to see if this worked
     if ($this->run($col+1)) {
     return true;
     }
     // this didn't work so let's remove the queen, backtrack, and try the next row
     $this->board[$row][$col] = 0;
     }
     }
     return false;
     }
     

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150. Algorithms
     public function run($col=0) : bool
     {
     // return true if we've iterated over the whole board
     if ($col >= $this->n) {
     return true;
     }
     // iterate over the rows
     for ($row = 0; $row < $this->n; ++$row) {
     if (!$this->hasCollision($row, $col)) {
     // place a queen
     $this->board[$row][$col] = 1;
     // check the next column to see if this worked
     if ($this->run($col+1)) {
     return true;
     }
     // this didn't work so let's remove the queen, backtrack, and try the next row
     $this->board[$row][$col] = 0;
     }
     }
     return false;
     }
     

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151. Algorithms
     public function run($col=0) : bool
     {
     // return true if we've iterated over the whole board
     if ($col >= $this->n) {
     return true;
     }
     // iterate over the rows
     for ($row = 0; $row < $this->n; ++$row) {
     if (!$this->hasCollision($row, $col)) {
     // place a queen
     $this->board[$row][$col] = 1;
     // check the next column to see if this worked
     if ($this->run($col+1)) {
     return true;
     }
     // this didn't work so let's remove the queen, backtrack, and try the next row
     $this->board[$row][$col] = 0;
     }
     }
     return false;
     }
     

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152. Algorithms
     public function run($col=0) : bool
     {
     // return true if we've iterated over the whole board
     if ($col >= $this->n) {
     return true;
     }
     // iterate over the rows
     for ($row = 0; $row < $this->n; ++$row) {
     if (!$this->hasCollision($row, $col)) {
     // place a queen
     $this->board[$row][$col] = 1;
     // check the next column to see if this worked
     if ($this->run($col+1)) {
     return true;
     }
     // this didn't work so let's remove the queen, backtrack, and try the next row
     $this->board[$row][$col] = 0;
     }
     }
     return false;
     }
     

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153. Algorithms
     public function run($col=0) : bool
     {
     // return true if we've iterated over the whole board
     if ($col >= $this->n) {
     return true;
     }
     // iterate over the rows
     for ($row = 0; $row < $this->n; ++$row) {
     if (!$this->hasCollision($row, $col)) {
     // place a queen
     $this->board[$row][$col] = 1;
     // check the next column to see if this worked
     if ($this->run($col+1)) {
     return true;
     }
     // this didn't work so let's remove the queen, backtrack, and try the next row
     $this->board[$row][$col] = 0;
     }
     }
     return false;
     }
     

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154. Algorithms
     public function run($col=0) : bool
     {
     // return true if we've iterated over the whole board
     if ($col >= $this->n) {
     return true;
     }
     // iterate over the rows
     for ($row = 0; $row < $this->n; ++$row) {
     if (!$this->hasCollision($row, $col)) {
     // place a queen
     $this->board[$row][$col] = 1;
     // check the next column to see if this worked
     if ($this->run($col+1)) {
     return true;
     }
     // this didn't work so let's remove the queen, backtrack, and try the next row
     $this->board[$row][$col] = 0;
     }
     }
     return false;
     }
     

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155. Algorithms
     public function run($col=0) : bool
     {
     // return true if we've iterated over the whole board
     if ($col >= $this->n) {
     return true;
     }
     // iterate over the rows
     for ($row = 0; $row < $this->n; ++$row) {
     if (!$this->hasCollision($row, $col)) {
     // place a queen
     $this->board[$row][$col] = 1;
     // check the next column to see if this worked
     if ($this->run($col+1)) {
     return true;
     }
     // this didn't work so let's remove the queen, backtrack, and try the next row
     $this->board[$row][$col] = 0;
     }
     }
     return false;
     }
     

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156. Algorithms
     public function run($col=0) : bool
     {
     // return true if we've iterated over the whole board
     if ($col >= $this->n) {
     return true;
     }
     // iterate over the rows
     for ($row = 0; $row < $this->n; ++$row) {
     if (!$this->hasCollision($row, $col)) {
     // place a queen
     $this->board[$row][$col] = 1;
     // check the next column to see if this worked
     if ($this->run($col+1)) {
     return true;
     }
     // this didn't work so let's remove the queen, backtrack, and try the next row
     $this->board[$row][$col] = 0;
     }
     }
     return false;
     }
     

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157. Algorithms
     public function run($col=0) : bool
     {
     // return true if we've iterated over the whole board
     if ($col >= $this->n) {
     return true;
     }
     // iterate over the rows
     for ($row = 0; $row < $this->n; ++$row) {
     if (!$this->hasCollision($row, $col)) {
     // place a queen
     $this->board[$row][$col] = 1;
     // check the next column to see if this worked
     if ($this->run($col+1)) {
     return true;
     }
     // this didn't work so let's remove the queen, backtrack, and try the next row
     $this->board[$row][$col] = 0;
     }
     }
     return false;
     }
     

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158. Algorithms
     public function hasCollision(int $row, int $col) : bool
     {
     // check the current row
     for ($thisCol = 0; $thisCol < $col; ++$thisCol) {
     if ($this->board[$row][$thisCol]) {
     return true;
     }
     }
     // check diagonally to the top left
     // no need to check the top right since we're processing one column at a time
     for ($thisRow = $row, $thisCol = $col; $thisRow >= 0 && $thisCol >= 0; $thisRow--, $thisCol--) {
     if ($this->board[$thisRow][$thisCol]) {
     return true;
     }
     }
     // check diagonally to the bottom left
     // no need to check the bottom right since we're processing one column at a time
     for ($thisRow = $row, $thisCol = $col; $thisCol >= 0 && $thisRow < $this->n; $thisRow++, $thisCol--) {
     if ($this->board[$thisRow][$thisCol]) {
     return true;
     }
     }
     return false;
     }
     

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159. Algorithms
     public function hasCollision(int $row, int $col) : bool
     {
     // check the current row
     for ($thisCol = 0; $thisCol < $col; ++$thisCol) {
     if ($this->board[$row][$thisCol]) {
     return true;
     }
     }
     // check diagonally to the top left
     // no need to check the top right since we're processing one column at a time
     for ($thisRow = $row, $thisCol = $col; $thisRow >= 0 && $thisCol >= 0; $thisRow--, $thisCol--) {
     if ($this->board[$thisRow][$thisCol]) {
     return true;
     }
     }
     // check diagonally to the bottom left
     // no need to check the bottom right since we're processing one column at a time
     for ($thisRow = $row, $thisCol = $col; $thisCol >= 0 && $thisRow < $this->n; $thisRow++, $thisCol--) {
     if ($this->board[$thisRow][$thisCol]) {
     return true;
     }
     }
     return false;
     }
     

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160. Algorithms
     public function hasCollision(int $row, int $col) : bool
     {
     // check the current row
     for ($thisCol = 0; $thisCol < $col; ++$thisCol) {
     if ($this->board[$row][$thisCol]) {
     return true;
     }
     }
     // check diagonally to the top left
     // no need to check the top right since we're processing one column at a time
     for ($thisRow = $row, $thisCol = $col; $thisRow >= 0 && $thisCol >= 0; $thisRow--, $thisCol--) {
     if ($this->board[$thisRow][$thisCol]) {
     return true;
     }
     }
     // check diagonally to the bottom left
     // no need to check the bottom right since we're processing one column at a time
     for ($thisRow = $row, $thisCol = $col; $thisCol >= 0 && $thisRow < $this->n; $thisRow++, $thisCol--) {
     if ($this->board[$thisRow][$thisCol]) {
     return true;
     }
     }
     return false;
     }
     

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161. Algorithms
     time complexity
     Brute Force = O(nn)
     
     Backtracking = O(n!)
     
     https://en.wikipedia.org/wiki/Eight_queens_puzzle
     

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162. Data Structures
     algorithms IRL
     
     https://en.wikipedia.org/wiki/Radix_tree
     

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163. View Slide

164. 🛠 WORKSHOP
     https://bit.ly/passTechInterview
     ↓
     Initial Phone Coding Test
     

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165. View Slide

166. 1

     Phone 

     Screen
     2

     Manager 

     Screen
     3

     Coding
     Test
     4
     Onsite
     Evals
     

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167. Stages
     4. Onsite Evals
     • 4-6 hours onsite
     
     • Fly in, if not local
     

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168. Stages
     4. Onsite Evals
     • Coding
     
     • Behavioral
     
     • System Design
     

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169. Stages
     4. Onsite Evals
     • Arrive Thursday night
     
     • Interviews start 9am Friday
     

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170. Stages
     4. Onsite Evals
     • 9-9:30 - arrival / meet recruiter
     
     • 9:30-10:20 - meet hiring manager
     
     • 10:30-11:20 - coding w/ 2 sr engineers
     
     • 11:30-12:20 - sys design w/ sr architect
     
     • 12:30-1:30 - lunch w/engineer on team
     
     • 1:30-2:20 - coding w/ 1 staff engineer
     
     • 2:30-3:20 - debrief w/ recruiter
     

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171. View Slide

172. Stages
     4. Onsite Evals
     • 9-9:30 - arrival / meet recruiter
     • 9:30-10:20 - meet hiring manager
     
     • 10:30-11:20 - coding w/ 2 sr engineers
     
     • 11:30-12:30 - sys design w/ sr architect
     
     • 12:30-1:30 - lunch w/engineer on team
     
     • 1:30-2:20 - coding w/ 1 staff engineer
     
     • 2:30-3:20 - debrief w/ recruiter
     

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173. Stages
     4. Onsite Evals
     • 9-9:30 - arrival / meet recruiter
     
     • 9:30-10:20 - meet hiring manager
     • 10:30-11:20 - coding w/ 2 sr engineers
     
     • 11:30-12:30 - sys design w/ sr architect
     
     • 12:30-1:30 - lunch w/engineer on team
     
     • 1:30-2:20 - coding w/ 1 staff engineer
     
     • 2:30-3:20 - debrief w/ recruiter
     

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174. Stages
     4. Onsite Evals
     • 9-9:30 - arrival / meet recruiter
     
     • 9:30-10:20 - meet hiring manager
     
     • 10:30-11:20 - coding w/ 2 sr engineers
     • 11:30-12:30 - sys design w/ sr architect
     
     • 12:30-1:30 - lunch w/engineer on team
     
     • 1:30-2:20 - coding w/ 1 staff engineer
     • 2:30-3:20 - debrief w/ recruiter
     

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175. Stages
     4. Onsite Evals
     • 9-9:30 - arrival / meet recruiter
     
     • 9:30-10:20 - meet hiring manager
     
     • 10:30-11:20 - coding w/ 2 sr engineers
     • 11:30-12:30 - sys design w/ sr architect
     
     • 12:30-1:30 - lunch w/engineer on team
     
     • 1:30-2:20 - coding w/ 1 staff engineer
     • 2:30-3:20 - debrief w/ recruiter
     

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176. Examples
     “Given an array of the 100 most common child
     names in 2021, sort them alphabetically”
     “List the top 10 products sold alphabetically on the
     sidebar of a site. Given an array of the top 1,000
     products where the key is their popularity and the value
     is the product name. Return an array.”
     Quicksort
     

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177. Examples
     “Given an array of the 100 most common child names in 2021, sort them
     alphabetically”
     Quicksort
     

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178. Examples
     “Given an array of the 100 most common child names in 2021, sort them
     alphabetically”
     const childNames = […];
     return childNames.quicksort();
     Quicksort
     

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179. Examples
     “List the top 10 products sold alphabetically on the sidebar of a site. Given an
     array of the top 1,000 products where the key is their popularity and the value
     is the product name. Return an array.”
     Quicksort
     

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180. Examples
     const products = […];
     return products.quicksort()
     .slice(0, 10)
     .quicksort();
     “List the top 10 products sold alphabetically on the sidebar of a site. Given an
     array of the top 1,000 products where the key is their popularity and the value
     is the product name. Return an array.”
     Quicksort
     

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181. Examples
     const products = […];
     return products.quicksort()
     .slice(0, 10)
     .quicksort();
     “List the top 10 products sold alphabetically on the sidebar of a site. Given an
     array of the top 1,000 products where the key is their popularity and the value
     is the product name. Return an array.”
     Quicksort
     

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182. 🛠 WORKSHOP
     https://bit.ly/passTechInterview
     ↓
     On-Site Coding Test
     

     View Slide

183. Stages
     4. Onsite Evals
     • 9-9:30 - arrival / meet recruiter
     
     • 9:30-10:20 - meet hiring manager
     
     • 10:30-11:20 - coding w/ 2 sr engineers
     
     • 11:30-12:30 - sys design w/ sr architect
     • 12:30-1:30 - lunch w/engineer on team
     
     • 1:30-2:20 - coding w/ 1 staff engineer
     
     • 2:30-3:20 - debrief w/ recruiter
     

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184. Examples
     System Design
     

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185. 🛠 WORKSHOP
     https://bit.ly/passTechInterview
     ↓
     On-Site Sys Design
     

     View Slide

186. Stages
     4. Onsite Evals
     • 9-9:30 - arrival / meet recruiter
     
     • 9:30-10:20 - meet hiring manager
     
     • 10:30-11:20 - coding w/ 2 sr engineers
     
     • 11:30-12:30 - sys design w/ sr architect
     
     • 12:30-1:30 - lunch w/engineer on team
     • 1:30-2:20 - coding w/ 1 staff engineer
     
     • 3:30-4 - debrief w/ recruiter
     

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187. Stages
     4. Onsite Evals
     • 9-9:30 - arrival / meet recruiter
     
     • 9:30-10:20 - meet hiring manager
     
     • 10:30-11:20 - coding w/ 2 sr engineers
     
     • 11:30-12:30 - sys design w/ sr architect
     
     • 12:30-1:30 - lunch w/engineer on team
     
     • 1:30-2:20 - coding w/ 1 staff engineer
     
     • 3:30-4 - debrief w/ recruiter
     

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188. View Slide

189. View Slide

190. Offer
     

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191. Negotiation
     

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192. Examples
     Career Ladder
     

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193. Total Comp =
     Salary + Equity + Benefits
     

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194. View Slide

195. Parting
     Thoughts
     

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196. Practice
     

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197. Examples
     

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198. View Slide

199. Resources
     https://randallkanna.com/get-the-ultimate-list/
     https://leetcode.com
     https://levels.fyi
     http://www.crackingthecodinginterview.com https://educative.io
     

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200. Let’s Work Together
     Wayfair Careers Portal
     https://www.wayfair.com/careers/jobs
     Email me
     ben.edmunds@gmail.com
     

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201. Thank You
     @benedmunds
     ben.edmunds@gmail.com
     

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