[ADD] Merge Sort

mergesort.cpp

@@ -0,0 +1,75 @@
+
+#include<iostream>
+#include<cmath>
+using namespace std;
+void merge(int A[],int p,int q,int r)
+{
+	int i,j,x,y;
+	int n1=q-p+1;int n2=r-q;
+	int B[n1],C[n2];
+	for(i=0;i<n1;i++)
+	{
+		B[i]=A[p+i];
+	}
+	for(x=0;x<n2;x++)
+	{
+		C[x]=A[q+1+x];
+	}int k;
+	i = 0,j = 0,k = p; 
+    while (i < n1 && j < n2)
+    {
+        if (B[i] <= C[j])
+        {
+            A[k] = B[i];
+            i++;
+        }
+        else
+        {
+            A[k] = C[j];
+            j++;
+        }
+        k++;
+    }
+
+    while (i < n1)
+    {
+        A[k] = B[i];
+        i++;
+        k++;
+    }
+
+    while (j < n2)
+    {
+        A[k] = C[j];
+        j++;
+        k++;
+    }
+}
+
+
+
+void mergesort(int A[],int p,int r)
+{int q;
+	if(p>=r)
+	{
+		return;
+	}
+	else
+	{
+	     q=(p+r)/2;
+		 mergesort(A,p,q);
+		 mergesort(A,q+1,r);
+		 merge(A,p,q,r);
+	}
+}
+
+int main()
+{
+	int A[5],a;
+	for(a=0;a<5;a++)
+	cin>>A[a];
+	mergesort(A,0,4);
+	for(a=0;a<5;a++)
+	cout<<A[a]<<" ";
+
+}