Don't forget to check the following links:
Notes and theory:
https://github.com/djeada/Leetcode-Solutions/blob/main/notes/23_merge_k_sorted_lists.md
Refined solution:
https://github.com/djeada/Leetcode-Solutions/blob/main/src/23_merge_k_sorted_lists.py
My blog:
https://adamdjellouli.com/