T6.3 (Я ненавижу это задание)

import java.util.Arrays;

import static java.lang.System.arraycopy;

public class MergeSort {
    int[] j;
    int[] k;

    public MergeSort(int[] a, int[] b){
        setA1(a);
        setA2(b);
    }

    public void setA1(int[] a1) {
        this.j = a1;
    }

    public void setA2(int[] a2) {
        this.k = a2;
    }

    public int[] getA1() {
        return j;
    }

    public int[] getA2() {
        return k;
    }

    public static int[] mergesort(int[] array1) {
        int[] buffer1 = Arrays.copyOf(array1, array1.length);
        int[] buffer2 = new int[array1.length];
        int[] result = mergesortInner(buffer1, buffer2, 0, array1.length);
        return result;
    }

    public static int[] mergesortInner(int[] buffer1, int[] buffer2,
                                       int startIndex, int endIndex) {
        if (startIndex >= endIndex - 1) {
            return buffer1;
        }

        // уже отсортирован.
        int middle = startIndex + (endIndex - startIndex) / 2;
        int[] sorted1 = mergesortInner(buffer1, buffer2, startIndex, middle);
        int[] sorted2 = mergesortInner(buffer1, buffer2, middle, endIndex);

        // Слияние
        int index1 = startIndex;
        int index2 = middle;
        int destIndex = startIndex;
        int[] result = sorted1 == buffer1 ? buffer2 : buffer1;
        while (index1 < middle && index2 < endIndex) {
            result[destIndex++] = sorted1[index1] > sorted2[index2]
                    ? sorted1[index1++] : sorted2[index2++];
        }
        while (index1 < middle) {
            result[destIndex++] = sorted1[index1++];
        }
        while (index2 < endIndex) {
            result[destIndex++] = sorted2[index2++];
        }
        return result;
    }

    public int[] merge() {
        int[] a1 = this.j;
        int[] a2 = this.k;
        int[] a3 = new int[a1.length + a2.length];
        int i=0, j=0, k=0;
        while(i < a1.length && j < a2.length) {
            a3[k++] = a1[i] < a2[j] ? a1[i++] : a2[j++];
        }
        if(i< a1.length) {
            arraycopy(a1, i, a3, k, a1.length - i);
        } else if(j< a2.length) {
            arraycopy(a2, j, a3, k, a2.length - j);
        }

        return a3;
    }
}
/////////////////////////////////////////////////////////////////
import java.util.Arrays;
public class Mass {
    protected int[] array;

    public Mass(int[] array){
        setArray(array);
    }

    public void setArray(int[] array) {
        this.array = array;
    }

    public void sort(){
        System.out.println(Arrays.toString(array));
        for (int left = 0; left < array.length; left++) {
            int value = array[left];
            int i = left - 1;
            for (; i >= 0; i--) {
                if (value > array[i]) {
                    array[i + 1] = array[i];
                } else {
                    break;
                }
            }
            array[i + 1] = value;
        }
        System.out.println(Arrays.toString(array));
    }


    public int[] getArray() {
        return array;
    }
}
 ////////////////////////////////////////////////////////////////////
import java.util.*;

public class Main {
    public static void main(String[] args){
        int[] a1 = new int[] {21, 23, 24, 40, 75, 76, 78, 77, 900, 2100, 2200, 2300, 2400, 2500};
        List<Integer> stud = new ArrayList<>();
        stud.add(3);
        stud.add(9);
        stud.add(5);
        stud.add(24);
        stud.add(64);
        stud.add(4);
        stud.add(34);

        System.out.println(stud.toString());
        Collections.sort(stud, new Comparator<Integer>() {

            @Override
            public int compare(Integer o1, Integer o2) {
                return o2 - o1;
            }
        });
        System.out.println(stud.toString());
        int[] b = new int[stud.size()];

        for ( int i = 0; i < stud.size(); i++ ) b[i] = stud.get(i);

        System.out.println(Arrays.toString(b));
        System.out.println(Arrays.toString(a1));
        MergeSort sorted = new MergeSort(b ,a1);

        int [] res = sorted.mergesort(sorted.merge());
        System.out.println( Arrays.toString(res));
    }
}