MergeSort_Methods

package com.company;

public class MergeSort_Methods {

    public static void Divide(int[] ARR, int l, int r) {

        if (l < r) {
            int m = (l + r) / 2; // sredna tochka

            Divide(ARR, l, m);// sort left
            Divide(ARR, m + 1, r);// sort right
            CompareAndMerge(ARR, l, m, r);
        }
    }

    private static void CompareAndMerge(int[] arr, int l, int m, int r) {
        int leftArrLength = m - l + 1;
        int rightArrLength = r - m;

        int[] L = new int[leftArrLength];
        int[] R = new int[rightArrLength];

        for (int i = 0; i < leftArrLength; i++) {
            L[i] = arr[l + i];

        }
        for (int j = 0; j < rightArrLength; j++) {
            R[j] = arr[m + 1 + j];
        }
        //sravnenie i mergvane na pomoshnite masivi
        int i = 0;
        int j = 0;
        int k = l;
//obhojda i svalq elementite
        while (i < leftArrLength && j < rightArrLength) {
            if (L[i] <= R[j]) {
                arr[k] = L[i];
                i++;
            } else {
                arr[k] = R[j];
                j++;
            }
            k++;
        }

        while (i < leftArrLength) {
            arr[k] = L[i];
            i++;
            k++;
        }
        while (j < rightArrLength) {//posledniq element go svalq prinuditelno
            arr[k] = R[j];
            j++;
            k++;
        }
    }

}