Class MergeSort

MergeSort.java:1–89

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];

		/*Copy data to temp arrays*/
		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];

		/* Merge the temp arrays */
		// Initial indexes of first and second subarrays
		int i = 0, j = 0;
		// Initial index of merged subarry array
		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++;
		}

		/* Copy remaining elements of L[] if any */
		while (i < n1) {
			arr[k] = L[i];
			i++;
			k++;
		}

		/* Copy remaining elements of R[] if any */
		while (j < n2) {
			arr[k] = R[j];
			j++;
			k++;
		}
	}

	// Main function that sorts arr[l..r] using
	// merge()
	void sort(int arr[], int l, int r)
	{
		if (l < r) {
			// Find the middle point
			int m =l+ (r-l)/2;

			// Sort first and second halves
			sort(arr, l, m);
			sort(arr, m + 1, r);