Question

how would you sort n sorted lists with average length K in O(n*log K) time?

Answer 1

As mentioned in the comments to your question, the O(nlog(k)) is not possible, but here are a couple of algorithms on this page that accomplish your task efficiently; here is one:

Take the first element of each list
and create a heap (of size k). Pop the
smallest element. Find the array from
the element came (let’s say it came
from list number i). Take the next
element from list i and push it in
heap. For each element that go in the
merged list, we spent log(k) time. So
the time complexity is O(N*logk) where
N is total number of the elements in
all the K lists.

-written by: Abhishek Goyal