MergeSort

public class MergeSort {

    void merge(int arr[], int l, int m, int r) {
        int n1 = m - l + 1;
        int n2 = r - m;

        int L[] = new int[n1];
        int R[] = new int[n2];

        for (int i = 0; i < n1; i++)
            L[i] = arr[l + i];

        for (int j=0; j < n2; j++)
            R[j] = arr[m + 1 + j];

        int i = 0, j = 0;
        int k = l;

        while ( i < n1 && j < n2){
            if(L[i] <= R[j])
            {
                arr[k] = L[i];
                i++;
            } else {
                arr[k] = R[j];
                j++;
            }
            k++;
        }

        while (i < n1)
        {
            arr[k] = L[i];
            i++;
            k++;
        }


        while (j < n2)
        {
            arr[k] = R[j];
            j++;
            k++;
        }
    }


    void sort(int arr[], int l, int r) {
        if (l < r)
        {
            int m = (l+r) / 2;

            sort(arr, l, m);
            sort(arr, m+1, r);

            merge(arr, l, m, r);
        }
    }


    static void printArray(int arr[]){
        int n = arr.length;
        for(int i=0; i < n; i++)
        {
            System.out.print(arr[i] + " ");
        }

        System.out.println();


    }

    public static void main(String[] args) {
        int arr[] = {12,11,13,5,6,7};

        System.out.println("Given Array");
        printArray(arr);

        MergeSort ob = new MergeSort();
        ob.sort(arr, 0, arr.length - 1);

        System.out.println("\nSorted Array");
        printArray(arr);

    }

}