Create MergeSort.java

SORTING AND SEARCHING/MergeSort.java

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+
+public class MergeSort {
+
+    public static void main(String args[]) {	
+		int arr[] = {23, 12, 85, 39, 98, 7, 16, 97, 54};
+
+		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);
+	}
+
+    void merge(int arr[], int low, int mid, int up) {	
+		int n1 = mid - low + 1;
+		int n2 = up - mid;
+
+		int Left[] = new int[n1];
+		int Right[] = new int[n2];
+
+		for (int i = 0; i < n1; ++i)
+			Left[i] = arr[low + i];
+		for (int j = 0; j < n2; ++j)
+			Right[j] = arr[mid + 1 + j];
+
+		int i = 0, j = 0;
+
+		int k = low;
+		while (i < n1 && j < n2) {
+			if (Left[i] <= Right[j]) {
+				arr[k] = Left[i];
+				i++;
+			}
+			else {
+				arr[k] = Right[j];
+				j++;
+			}
+			k++;
+		}
+		while (i < n1) {
+			arr[k] = Left[i];
+			i++;
+			k++;
+		}
+		while (j < n2) {
+			arr[k] = Right[j];
+			j++;
+			k++;
+		}
+	}
+
+	void sort(int arr[], int low, int up) {	
+		if (low < up) {
+			int mid =low + (up-low)/2;
+
+			sort(arr, low, mid);
+			sort(arr, mid + 1, up);
+
+			merge(arr, low, mid, up);
+		}
+	}
+
+	static void printArray(int arr[]) {	
+		int n = arr.length;
+		for (int i = 0; i < n; ++i)
+			System.out.print(arr[i] + " ");
+		System.out.println();
+	}	
+}