optimized kth minimum element using priority queue

[Yashaswini-K-P]

What I changed

• Replaced the existing sort-based approach for finding the kth minimum element with a priority queue (min-heap) approach.
• This optimizes the code by reducing the time complexity from O(n log n) to O(n log k), making it more efficient for large inputs, where usually k will be smaller than n

Why

• Sorting the entire array is unnecessary to find the kth minimum element.
• Using a priority queue improves performance and reduces runtime for large datasets.

This PR is part of my Hacktoberfest contribution — if valid, could a maintainer please add the hacktoberfest-accepted label? Thank you!

[Yashaswini-K-P]

Hi! This PR is part of my Hacktoberfest contribution.
If valid, could you please add the hacktoberfest-accepted label? Thanks!