Search for Viral Meme Groups - 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 sorted list of tuples, where each tuple contains a meme name (string) and its popularity score (integer).

• Q: What is the output?

  • A: The output is a tuple containing the names of the two memes whose combined popularity score is closest to the target value.

• Q: What should the function return if no such pair exists?

  • A: The function will always find a pair since the list contains at least two memes.

• Q: How should ties be handled when multiple pairs have the same difference?

  • A: The first pair found with the closest difference should be returned.

P-lan

Plan the solution with appropriate visualizations and pseudocode.

General Idea: Use a two-pointer approach to find the pair of memes whose combined popularity score is closest to the target value.

1) Initialize two pointers, `left` at the start and `right` at the end of the list.
2) Initialize variables `closest_pair` to store the closest meme pair and `closest_diff` to store the smallest difference found.
3) While `left` is less than `right`:
   a) Calculate the combined popularity score of the memes at the `left` and `right` pointers.
   b) Calculate the difference between this combined score and the target value.
   c) If this difference is smaller than the current `closest_diff`, update `closest_diff` and `closest_pair`.
   d) If the combined score is less than the target, move the `left` pointer to the right to increase the sum.
   e) If the combined score is greater than or equal to the target, move the `right` pointer to the left to decrease the sum.
4) Return the `closest_pair` once the pointers meet.

**⚠️ Common Mistakes**

- Not updating the pointers correctly based on the comparison between the current sum and the target.
- Mismanaging the initialization or update of `closest_diff` and `closest_pair`.

I-mplement

def find_closest_meme_pair(memes, target):
    left = 0
    right = len(memes) - 1
    closest_pair = ()
    closest_diff = float('inf')

    while left < right:
        meme1, score1 = memes[left]
        meme2, score2 = memes[right]
        current_sum = score1 + score2
        current_diff = abs(target - current_sum)

        if current_diff < closest_diff:
            closest_diff = current_diff
            closest_pair = (meme1, meme2)

        if current_sum < target:
            left += 1
        else:
            right -= 1

    return closest_pair