315. Merge K Sorted Lists

You are given an array of k sorted linked-lists. Merge all the linked-lists into one sorted linked-list and return it.

For this problem, treat each list as a simple Python/JavaScript list. Merge all lists into a single sorted list.

Example:
Input: lists = [[1,4,5],[1,3,4],[2,6]]
Output: [1,1,2,3,4,4,5,6]

Run this challenge interactively in Python or JavaScript when the app loads.