Solution: Kth Smallest Number in M Sorted Lists

Statement

Given $m$ sorted lists in ascending order and an integer $k$, find the $k^{th}$ smallest element among all the lists.

Even if some values appear multiple times across the lists, each occurrence is treated as a unique element when determining the $k^{th}$ smallest number.

If $k$ exceeds the total number of elements across all lists, return the largest element among them. If the lists are empty, return $0$.