Added MergeSort

Java/MergeSort.java

@@ -0,0 +1,78 @@
+package sorting;
+
+public class MergeSort {
+
+	public void sort(int a[],int l,int r)
+	{
+		if(l<r)
+		{
+			int m=l+(r-l)/2;
+			sort(a,l,m);
+			sort(a,m+1,r);
+			merge(a,l,m,r);
+		}
+	}
+	public void merge(int a[],int l, int m,int r)
+	{
+		//declare size of two temporary subarrays
+		int n1= m-l+1;
+		int n2=	r-m;	
+		//create two temporary arrays
+		int L[]=new int[n1];
+		int R[]=new int[n2];
+
+		//copying elements to temporary arrays
+		for(int i=0;i<n1;i++)
+		{
+			L[i]=a[l+i];
+		}
+		for(int j=0;j<n2;j++)
+		{
+			R[j]=a[m+1+j];
+		}
+		int i=0,j=0;
+		int k=l;
+		while(i<n1 && j<n2)
+		{
+			if(L[i]<=R[j])
+			{
+				a[k]=L[i++];
+			}
+			else
+			{
+				a[k]=R[j++];
+			}
+			k++;
+		}
+		//copying remaining elements from L[]
+		while(i<n1)
+		{
+			a[k++]=L[i++];
+		}
+		//copying remaining elements from R[]
+		while(j<n2)
+		{
+			a[k++]=R[j++];
+		}	
+	}
+	public void display(int a[])
+	{
+		int n=a.length;
+		for(int i=0;i<n;i++)
+		{
+			System.out.print(a[i]+" ");
+
+		}
+	}
+	public static void main(String args[])
+	{
+		int a[]= {-8,7,2,10,56,30,38,25,10,-1};
+		MergeSort ob=new MergeSort();
+		System.out.println("Original Array");
+		ob.display(a);
+		ob.sort(a, 0, a.length-1);
+		System.out.println();
+		System.out.println("Sorted Array");
+		ob.display(a);
+	}
+}