Create MergeSort.java

Sorting Algorithms/MergeSort.java

@@ -0,0 +1,66 @@
+class MergeSort {
+	private 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++;
+		}
+	}
+
+	public 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);
+		}
+	}
+
+	public 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 };
+		printArray(arr);
+
+		MergeSort ob = new MergeSort();
+		ob.sort(arr, 0, arr.length - 1);
+		printArray(arr);
+	}
+}