more robust and easier to understand.

[Anshuman7080]

Boundary Check: Added a boundary check for k in the main function to ensure it is within valid range. Return Value for Out of Bounds: Added a return value of INT_MAX if k is out of bounds in the find_kth_smallest function. Vector Usage: Used vector for dynamic array allocation, which is safer and more modern C++ practice. Simplified Partition Logic: Improved the readability of the partition logic.