Nook's Cranny - codepath/compsci_guides GitHub Wiki

TIP102 Unit 5 Session 1 Standard (Click for link to problem statements)

Problem Highlights

  • 💡 Difficulty: Easy
  • ⏰ Time to complete: 5-10 mins
  • 🛠️ Topics: Classes, Linked Lists, Pointers

1: U-nderstand

Understand what the interviewer is asking for by using test cases and questions about the problem.

  • Established a set (2-3) of test cases to verify their own solution later.
  • Established a set (1-2) of edge cases to verify their solution handles complexities.
  • Have fully understood the problem and have no clarifying questions.
  • Have you verified any Time/Space Constraints for this problem?

  • What is a linked list?

    • A data structure where each element (node) contains a value and a reference to the next node in the list.

  • How do we create a linked list?

    • By instantiating nodes and linking them using the next attribute.
HAPPY CASE
Input: 
tom_nook = Node("Tom Nook")
tommy = Node("Tommy")
tom_nook.next = tommy
print(tom_nook.value) # Output: Tom Nook
print(tom_nook.next.value) # Output: Tommy
print(tommy.value) # Output: Tommy
print(tommy.next) # Output: None

Explanation: 
The linked list is created correctly, with `tom_nook` pointing to `tommy`.

EDGE CASE
Input: 
node1 = Node("Node 1")
print(node1.value) # Output: Node 1
print(node1.next) # Output: None

Explanation: 
A single node without a next node should have its `next` attribute set to `None`.

2: M-atch

Match what this problem looks like to known categories of problems, e.g. Linked List or Dynamic Programming, and strategies or patterns in those categories.

For Linked List problems, we want to consider the following approaches:

  • Create nodes and link them using the next attribute.
  • Ensure the last node points to None.

3: P-lan

Plan the solution with appropriate visualizations and pseudocode.

General Idea: Create the nodes and link them to form the linked list.

1) Define the `Node` class with `__init__` method to initialize `value` and `next` attributes.
2) Create an instance of `Node` for `tom_nook` with value "Tom Nook".
3) Create an instance of `Node` for `tommy` with value "Tommy".
4) Link `tom_nook` to `tommy` using the `next` attribute.

⚠️ Common Mistakes

  • Forgetting to set the next attribute to link the nodes.
  • Incorrectly referencing the next attribute.

4: I-mplement

Implement the code to solve the algorithm.

class Node:
    def __init__(self, value, next=None):
        self.value = value
        self.next = next

# Create the nodes
tom_nook = Node("Tom Nook")
tommy = Node("Tommy")

# Link the nodes
tom_nook.next = tommy

5: R-eview

Review the code by running specific example(s) and recording values (watchlist) of your code's variables along the way.

  • Instantiate the nodes tom_nook and tommy.
  • Validate the linked list by checking the value and next attributes.
  • Ensure the nodes are linked correctly.

6: E-valuate

Evaluate the performance of your algorithm and state any strong/weak or future potential work.

Assume N represents the number of nodes in the linked list.

  • Time Complexity: O(1) because creating and linking nodes are constant-time operations.
  • Space Complexity: O(1) for each node instance created.