Methods - MergeSort

package MergeSort183_02;

public class MergeSort_Methods {
    public static void Divide(int []arr,int l ,int r) {

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

            Divide(arr,l,m); // Recursive Left;
            Divide(arr, m + 1,r); //Recursive Left;

            CompareAndMergeArr(arr,l,m,r);

        }
    }


    private static void CompareAndMergeArr(int []arr,int l,int m,int r) {

        int LeftArrLenght = m - l + 1 ;
        int RightArrLenght = r - m ;

        int [] L = new int [LeftArrLenght];
        int [] R = new int [RightArrLenght];

        for (int i = 0; i < LeftArrLenght ; i++) {
            L[i] = arr[l + i];
        }
        for (int j = 0; j < RightArrLenght; j++) {
            R[j] = arr[m + 1 + j];
        }

        int i = 0; // index for left array
        int j = 0; // index for right array
        int k = l;

        while( i < LeftArrLenght && j < RightArrLenght){

            if(L[i] <= R[j]){
                arr[k] = L[i];
                i++;
            }
            else{
                arr[k] = R[j];
                j++;
            }
            k++;

        }

        //Collect any elements from L and R if any

        while(i < LeftArrLenght){
            arr[k]  = L[i];
            i++;
            k++;
        }
        while( j < RightArrLenght){
            arr[k] = R[j];
            j++;
            k++;
        }



    }
}