**Problem Statement:**
Given the required input arguments, write an efficient algorithm to solve the **Merge K Sorted Lists** problem. Implement the required logic as specified by standard definitions for this classic algorithmic challenge.
**Hint / Expected Approach:**
Min-heap of (val, listIndex) OR divide-and-conquer merge
**Edge Cases to Consider:**
- (1) All lists empty
- (2) Single list
- (3) Lists of vastly different lengths
Examples
Example 1
Input:[[1,4,5],[1,3,4],[2,6]]
Output:[1,1,2,3,4,4,5,6]
Explanation: Classic 3-list merge
Example 2
Input:[]
Output:[]
Explanation: No lists
Example 3
Input:[[]]
Output:[]
Explanation: One empty list
Constraints
▪The number of nodes in the list is in the range [0, 500]