CodePath - Linked List

Transcript

1. Linked Lists
   Week 3
   What’s a good memory you have from this week?
   -> I had an amazingly tasty burger
   🍔
   

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2. Addressing Feedback
   - Panel was well-received
   - Office hours are posted on course portal now
   - Zoom issues should be resolved
   

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3. Linked Lists
   

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4. What is a Linked List?
   Individual elements (nodes) that each hold two
   pieces of information:
   1) data (integer, string, anything!)
   2) reference to the next node
   

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6. Why are they useful?
   

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7. Why are they useful?
   Web browser’s history (previous / next page)
   

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8. Why are they useful?
   Web browser’s history (previous / next page)
   Memory management (blocks of memories)
   

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9. Why are they useful?
   Web browser’s history (previous / next page)
   Memory management (blocks of memories)
   Hash tables (resolving collisions)
   

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10. Types of Linked Lists
    

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11. Singly linked
    Doubly linked
    Circularly linked
    Types of Linked Lists
    

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12. Singly linked
    Doubly linked
    Circularly linked
    Types of Linked Lists
    

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13. Pros and Cons
    Always think about space / time complexity when
    choosing a data structure!
    

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14. Pros and Cons
    Always think about space / time complexity when
    choosing a data structure!
    Good for:

    - insertion / deletion from one end 

    

    

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15. Pros and Cons
    Always think about space / time complexity when
    choosing a data structure!
    Good for:

    - insertion / deletion from one end 

    

    Bad for:

    - searching
    

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16. Pros and Cons
    Always think about space / time complexity when
    choosing a data structure!
    Good for:

    - insertion / deletion from one end 

    

    Bad for:

    - searching
    https://guides.codepath.org/compsci/Linked-Lists
    

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17. Linked List Tips and Tricks
    

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18. Linked List Tips and Tricks
    Take multiple passes through the linked list

    - get length 

    - save other information about contents
    

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19. Linked List Tips and Tricks
    Take multiple passes through the linked list

    - get length 

    - save other information about contents
    Two pointers

    - ‘race car’ strategy with one regular pointer, and
    one fast pointer
    

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20. Linked List Tips and Tricks
    Take multiple passes through the linked list

    - get length 

    - save other information about contents
    Two pointers

    - ‘race car’ strategy with one regular pointer, and
    one fast pointer
    Dummy node

    - helpful for preventing errors when returning
    ‘head’ (merging lists, deleting from lists)
    

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21. Understand
    Match
    Pseudocode / Plan
    Implement
    Review
    Evaluate
    

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22. Plan / Pseudocode
    Start to figure out how you would solve the problem
    Can you create any ‘magic’ helper methods that would simplify
    the solution? (ie : getLength(), reverse() )
    Talk through different approaches you can take, and their
    tradeoffs
    Be able to verbally describe your approach and explain how an
    example input would produce the desired output
    

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23. Example: Remove Nth Node
    from End of List
    Understand: Always start by understanding the question and
    running through an example
    

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24. Example: Remove Nth Node
    from End of List
    Understand: Always start by understanding the question and
    running through an example
    1->2->3->4->5, n = 2

    

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25. Example: Remove Nth Node
    from End of List
    Understand: Always start by understanding the question and
    running through an example
    1->2->3->4->5, n = 2

    return 1->2->3->5
    

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26. Example: Remove Nth Node
    from End of List
    Understand: Always start by understanding the question and
    running through an example
    1, n = 1

    

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27. Example: Remove Nth Node
    from End of List
    Understand: Always start by understanding the question and
    running through an example
    1, n = 1

    return null
    

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28. Example: Remove Nth Node
    from End of List
    Understand: Always start by understanding the question and
    running through an example
    1->2->3->4->5, n = 2

    return 1->2->3->5
    Let’s assume we start without any time / space constraints. So
    our goal is to figure out ANY kind of solution to produce the right
    answer
    Any other questions??
    

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29. Example: Remove Nth Node
    from End of List
    Match : Are there any special techniques that we can use to
    help make this easier?

    

    

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30. Example: Remove Nth Node
    from End of List
    Match : Are there any special techniques that we can use to
    help make this easier?

    -> We can take a first pass through the linked list to store the
    elements in an array 

    

    

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31. Example: Remove Nth Node
    from End of List
    Match : Are there any special techniques that we can use to
    help make this easier?

    -> We can take a first pass through the linked list to store the
    elements in an array 

    -> We can also take a pass to get the length of the linked list
    

    

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32. Example: Remove Nth Node
    from End of List
    Match : Are there any special techniques that we can use to
    help make this easier?

    -> We can take a first pass through the linked list to store the
    elements in an array 

    -> We can also take a pass to get the length of the linked list
    Plan : What are some different ways we can solve this problem?

    

    

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33. Example: Remove Nth Node
    from End of List
    Match : Are there any special techniques that we can use to
    help make this easier?

    -> We can take a first pass through the linked list to store the
    elements in an array 

    -> We can also take a pass to get the length of the linked list
    Plan : What are some different ways we can solve this problem?

    1) We can store the elements in an array, get the length of the
    array, and then rebuild our list excluding the nth to last node

    

    

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34. Example: Remove Nth Node
    from End of List
    Match : Are there any special techniques that we can use to
    help make this easier?

    -> We can take a first pass through the linked list to store the
    elements in an array 

    -> We can also take a pass to get the length of the linked list
    Plan : What are some different ways we can solve this problem?

    1) We can store the elements in an array, get the length of the
    array, and then rebuild our list excluding the nth to last node

    2) We can follow the first idea, but instead of storing things in an
    array, remove the reference to the nth to last node the second
    time we iterate through the list

    

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35. Example: Remove Nth Node
    from End of List
    Match : Are there any special techniques that we can use to
    help make this easier?

    -> We can take a first pass through the linked list to store the
    elements in an array 

    -> We can also take a pass to get the length of the linked list
    Plan : What are some different ways we can solve this problem?

    1) We can store the elements in an array, get the length of the
    array, and then rebuild our list excluding the nth to last node

    2) We can follow the first idea, but instead of storing things in an
    array, remove the reference to the nth to last node the second
    time we iterate through the list

    What would be the space / time complexity of our solution?
    

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36. Example: Remove Nth Node
    from End of List
    Our approach:

    1) make initial pass through linked list to get length

    2) make second pass to remove any reference to nth to last node

    

    

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37. Example: Remove Nth Node
    from End of List
    Our approach:

    1) make initial pass through linked list to get length

    2) make second pass to remove any reference to nth to last node

    

    Let’s draw out how this might work with an example

    Given linked list 1->2->3, n = 1 (we want to return 1->2)
    

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38. Example: Remove Nth Node
    from End of List
    Our approach:

    1) make initial pass through linked list to get length

    2) make second pass to remove any reference to nth to last node

    

    Let’s draw out how this might work with an example

    Given linked list 1->2->3, n = 1 (we want to return 1->2)
    First pass, we get length = 3.

    

    

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39. Example: Remove Nth Node
    from End of List
    Our approach:

    1) make initial pass through linked list to get length

    2) make second pass to remove any reference to nth to last node

    

    Let’s draw out how this might work with an example

    Given linked list 1->2->3, n = 1 (we want to return 1->2)
    First pass, we get length = 3. Since n = 1, that means we want to remove
    the 3 -1 = 2 node (with index starting at 0)

    

    

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40. Example: Remove Nth Node
    from End of List
    Our approach:

    1) make initial pass through linked list to get length

    2) make second pass to remove any reference to nth to last node

    

    Let’s draw out how this might work with an example

    Given linked list 1->2->3, n = 1 (we want to return 1->2)
    First pass, we get length = 3. Since n = 1, that means we want to remove
    the 3 -1 = 2 node (with index starting at 0)

    

    As we iterate through the list..

    at node 1 -> numberOfNodesSeen = 0
    

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41. Example: Remove Nth Node
    from End of List
    Our approach:

    1) make initial pass through linked list to get length

    2) make second pass to remove any reference to nth to last node

    

    Let’s draw out how this might work with an example

    Given linked list 1->2->3, n = 1 (we want to return 1->2)
    First pass, we get length = 3. Since n = 1, that means we want to remove
    the 3 -1 = 2 node (with index starting at 0)

    

    As we iterate through the list..

    at node 1 -> numberOfNodesSeen = 0

    at node 2-> numberOfNodesSeen = 1
    

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42. Example: Remove Nth Node
    from End of List
    Our approach:

    1) make initial pass through linked list to get length

    2) make second pass to remove any reference to nth to last node

    

    Let’s draw out how this might work with an example

    Given linked list 1->2->3, n = 1 (we want to return 1->2)
    First pass, we get length = 3. Since n = 1, that means we want to remove
    the 3 -1 = 2 node (with index starting at 0)

    

    As we iterate through the list..

    at node 1 -> numberOfNodesSeen = 0

    at node 2-> numberOfNodesSeen = 1

    at node 3 -> numberOfNodesSeen = 2 -> at this point we need to set
    node 2’s next to be node 3’s next!
    

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43. Example: Remove Nth Node
    from End of List
    Our approach:

    1) make initial pass through linked list to get length

    2) make second pass to remove any reference to nth to last node

    

    Let’s draw out how this might work with an example

    Given linked list 1->2->3, n = 1 (we want to return 1->2)
    First pass, we get length = 3. Since n = 1, that means we want to remove
    the 3 -1 = 2 node (with index starting at 0)

    

    As we iterate through the list..

    at node 1 -> numberOfNodesSeen = 0, previousNode = null

    at node 2-> numberOfNodesSeen = 1, previousNode = 1

    at node 3 -> numberOfNodesSeen = 2, previousNode = 2 -> we set
    previousNode.next = node.next (node 3’s next = null)
    

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44. Breakout Rooms
    - Turn on your camera
    - Assign a timekeeper

    - Breakout rooms will close at 11:30 am PT

    - Take a 5 min break right before then!
    - Open the Course Portal and go to this week’s Session #2 tab

    - Read the At a Glance

    - Start with the Icebreaker!
    - If your pod needs help, post a message in the @se102-help-fall21 slack
    channel and tag @se102-tas
    

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45. Evaluating companies
    

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46. Evaluating companies
    Glassdoor reviews
    
    Researching current people who work at the company
    on LinkedIn
    
    

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47. Questions for me?
    

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48. Questions for me?
    Work Life Balance
    

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49. Questions for me?
    Work Life Balance
    - How does the team figure out what to work on in the
    next 3-6 months?
    
    - How does the team tackle tech debt?
    
    - What is a typical release process?
    
    - Weekly? Biweekly?
    
    - How does the team prepare for releases?
    
    - How is the release monitored afterwards?
    
    - Are there oncall schedules?
    

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50. Questions for me?
    Career Growth
    

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51. Questions for me?
    Career Growth
    - What do you see me working on in my first 3-6
    months on the job?
    
    - How do people on the team get feedback usually?
    
    

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52. Questions for me?
    General
    - What are some challenging projects you’ve worked
    on in the past 3-6 months?
    
    - What kind of meetings do you usually have in a
    week?
    
    

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53. Questions for me?
    Other questions?
    

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54. Survey
    

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