Reverse Meme Order - codepath/compsci_guides GitHub Wiki

Unit 4 Session 1 Standard (Click for link to problem statements)

U-nderstand

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

• Q: What is the structure of the input?

  • A: The input is a list of strings, where each string represents a meme.

• Q: What is the output?

  • A: The output is a list of strings, where the memes are in reverse order compared to the input list.

• Q: What should the function return if the input list is empty?

  • A: The function should return an empty list.

• Q: Are there any constraints on the input, such as the length of the list?

  • A: The problem does not specify constraints, so we assume the list can be of any length.

P-lan

Plan the solution with appropriate visualizations and pseudocode.

General Idea: Use a stack to reverse the order of the memes. Push all memes onto the stack and then pop them off to get them in reverse order.

1) Initialize an empty list called `stack` to simulate stack behavior.
2) Initialize an empty list called `reversed_memes` to store the memes in reverse order.
3) Iterate through each meme in the input list and push it onto the stack.
4) While the stack is not empty, pop memes from the stack and append them to `reversed_memes`.
5) Return the `reversed_memes` list as the output.

**⚠️ Common Mistakes**

- Forgetting to handle cases where the input list is empty.
- Using a method that does not actually reverse the list order correctly.

I-mplement

def reverse_memes(memes):
    stack = []
    reversed_memes = []

    # Push all memes onto the stack
    for meme in memes:
        stack.append(meme)

    # Pop all memes from the stack to reverse the order
    while stack:
        reversed_memes.append(stack.pop())

    return reversed_memes