Merging K- Sorted Lists using Priority Queue

Question

I have been asked in my algorithm class to make a K-way merge algorithm which is of O(nlogk) After searching i found it could be done via making a k length prio

Answer 1

I wrote a series of articles about this some years ago when discussing sorting a large text file. The idea is that the items you put on the heap contain not just the value but also the list the value came from. Or, you could just put the list reference on the heap and have the comparison function compare against the first item in the particular list.

See http://www.informit.com/guides/content.aspx?g=dotnet&seqNum=676 and http://www.informit.com/guides/content.aspx?g=dotnet&seqNum=677 for an explanation of the basic algorithm using a sequential list in place of a heap. See http://www.informit.com/guides/content.aspx?g=dotnet&seqNum=680 for an improved version that uses a heap.

As I said in my comment, you can also do the merge without a heap. See https://stackoverflow.com/a/18984961/56778 for a description.