Java：将列表分为已排序的“块”，以完全对列表进行排序

Question

Okay, first post here, so please bear with me.

So I'm trying to work this out on my own as much as possible, but I'm at a bit of a loss here. I have been given a list ( and will be given many more to test, but I'm working with this one) of 12 integers. The list is as follows:

18 21 9 12 99 4 101 8 14 7 112 98

and a chunk is defined as an already sorted grouping of integers. This means there are 6 chunks. Since this is a recursive chunk merge sort, I need to be able to break it up based on the chunks.

The first split would look like:

18 21 9 12 99 4 101 | 8 14 7 112 98

and the second would look like:

18 21 | 9 12 99 | 4 101 ||| 8 14 | 7 112 | 98

As you can see, this means six chunks. Now, I have managed to get to the first step, but it is not done via recursion, or through these chunks. I cheated and took the size of the list and cut it in half. That's a no go.

I am open to trying out any suggestion, I am just stumped at how to go about breaking this down into these chunks, especially if I cannot dictate the number of "chunks" going in.

Here's a chunk of my code, if it helps:

    public List<Integer> chunkMergesort(List<Integer> S) {
    int c = 0;

    if(S.size() > 1){
        c = 1;
        for(int i = 0; i<S.size()-1 ; i++){
            if(S.get(i+1)< S.get(i)){
                c++;
                System.out.println("C is: " + c);
            }
        }
        System.out.println("Final C is: " + c);
        chunkDivide(S, c);
    }
        return S;
}

public Chunks chunkDivide(List<Integer> S, int c) {

    int Ssize = S.size()/2;
    System.out.println("List:"+ S);

    List<Integer> S1 = new ArrayList<Integer>();
    List<Integer> S2 = new ArrayList<Integer>();

    for(int i = 0; i < Ssize; i++){
        //System.out.println("i is: "+ i);
        S1.add(i, S.get(i));    
        System.out.println("S1 is:"+ S1);
    }

    for(int i = Ssize; i < S.size(); i++){
        S2.add(i-Ssize, S.get(i));
        System.out.println("S2 is:"+ S2);

    }

    System.out.println("S1 is: "+ S1);
    System.out.println("S2 is: "+ S2);      

    Chunks p = new Chunks(S1, S2);

    //chunkMergesort(S1);
    //chunkMergesort(S2);
    //chunkDivide(p.right, mid);
    //chunkDivide(p.left, mid);

    merge(S1,S2);

    return p;

Thanks in advance!

EDIT:

I ended up using something similar to what was suggested by @Eritrean but a whole new issue arose. My list is moved into a List of chunks, but the last item in the list (98) which should be the last chunk as well, gets dropped. I tried to ask how to fix this issue in another question, and was immediately dismissed as it being a duplicate. Those "answers" don't actually answer my question. Any more insight into this would be wonderful.

Below will be my image showing the output. CMD Snip

Answer 1

You can iterate through the list and look for sorted parts of the list by comparing current element by its successors. Then you can add this parts to a list of lists using the method list.subList(int fromIndex, int toIndex). Example:

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class NewClass {

    public static void main(String[] args) {
        List<Integer> intList = Arrays.asList(18, 21, 9, 12, 99, 4, 101, 8, 14, 7, 112, 98);

        List<List<Integer>> chunks = breakIntoChunks(intList);

        for(List<Integer> chunk : chunks){
            System.out.println(chunk);
        }
    }

    private static List<List<Integer>> breakIntoChunks(List<Integer> intList) {
        List<List<Integer>> chunks = new ArrayList<>();
        int curr =0;
        for(int i = 0; i<intList.size()-1; i++){
            if(intList.get(i).compareTo(intList.get(i+1))>0 || i==intList.size()-1){
                chunks.add(intList.subList(curr, i+1));
                curr = i+1;
            }
         }
         if(curr<=intList.size()){
              chunks.add(intList.subList(curr,intList.size()));
         }
         return chunks;       
      }
  }