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

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

Problem Highlights

💡 Difficulty: Easy
⏰ Time to complete: 10-15 mins
🛠️ Topics: Classes, Object-Oriented Programming, Linked List, Traversal

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?

How do we determine if a message can be passed from the start_villager to the target_villager?
- By traversing through the neighbors of the start_villager and checking if we reach the target_villager.
What attributes and methods are relevant for this problem?
- The neighbor attribute of the Villager class.

HAPPY CASE
Input: 
isabelle = Villager("Isabelle", "Dog", "Normal", "what's up?")
tom_nook = Villager("Tom Nook", "Raccoon", "Cranky", "yes, yes")
kk_slider = Villager("K.K. Slider", "Dog", "Lazy", "dig it")
isabelle.neighbor = tom_nook
tom_nook.neighbor = kk_slider
result = message_received(isabelle, kk_slider)

Output: 
True

Explanation: 
The message can be passed from Isabelle to Tom Nook, and then from Tom Nook to KK Slider.

EDGE CASE
Input: 
isabelle = Villager("Isabelle", "Dog", "Normal", "what's up?")
kk_slider = Villager("K.K. Slider", "Dog", "Lazy", "dig it")
result = message_received(kk_slider, isabelle)

Output: 
False

Explanation: 
KK Slider has no neighbor, so the message cannot be passed to Isabelle.

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:

Traverse the linked list using a loop.
Check each node for a condition and move to the next node if the condition is not met.

3: P-lan

Plan the solution with appropriate visualizations and pseudocode.

General Idea: Traverse the neighbors of start_villager and check if we can reach target_villager.

1) Define the `message_received` function.
2) Initialize a variable `current` to `start_villager`.
3) While `current` is not None:
    a) If `current` is `target_villager`, return True.
    b) Move to the next neighbor by setting `current` to `current.neighbor`.
4) If the loop exits without finding `target_villager`, return False.

⚠️ Common Mistakes

Forgetting to check for None to avoid infinite loops.
Not correctly updating the current variable to move to the next neighbor.

4: I-mplement

Implement the code to solve the algorithm.

class Villager:
    def __init__(self, name, species, personality, catchphrase, neighbor=None):
        self.name = name
        self.species = species
        self.personality = personality
        self.catchphrase = catchphrase
        self.furniture = []
        self.neighbor = neighbor

def message_received(start_villager, target_villager):
    current = start_villager
    while current is not None:
        if current == target_villager:
            return True
        current = current.neighbor
    return False

5: R-eview

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

Create instances of Villager and link them as neighbors.
Validate the function with different start_villager and target_villager pairs.
Ensure the function correctly traverses the neighbors and returns the expected results.

6: E-valuate

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

Assume N represents the number of neighbors in the chain.

Time Complexity: O(N) because we need to traverse the chain of neighbors.
Space Complexity: O(1) because we are using a fixed amount of space for the traversal.