I am trying to come up with a divide and conquer algorithm for merging j sorted lists with n number of elements but I'm stuck; I don't know how to divide this problem into smaller sub-problems. I want it to be more efficient that the merging algorithm that goes like this:
Merge the first two lists; then merge the resulting list with the third list; then merge the resulting list with the fourth list, etc. which takes O(j * jn).