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javaheapsort

Top k results of a List Java

I am using a Heap sort algorithm to sort an Object List and that is working fine. The problem is when I am trying to get the top k results of the list using this code:

HeapSort.sort(songs);
List<Song> highk = songs.subList(songs.size() - k, songs.size());
System.out.println(highk);

This prints the last k elements of the list. The k is fine because even if I change it with a number I have the same problem.

Solution

  • If you want top k elements, then your method call should be like below:

    List<Song> highk = songs.subList(0, k);

    When you see the java doc comments of the subList method, it clearly says, first argument is fromIndex and second argument is toIndex (here).