CREATED MERGE SORT IN N/4

CREATED MERGE SORT IN N/MERGE SORT IN N/N/MERGESORTIN ONE FOURTH. IN C++

@@ -0,0 +1,106 @@
+#include <bits/stdc++.h>
+using namespace std;
+void merge(int arr[], int start,int mid1, int mid, int mid2,int end)
+{
+
+    int n1 =mid1-start+1;
+    int n2 = mid-mid1;
+    int n3 = mid2-mid;
+    int n4 =end-mid2 ;
+
+    int akrr[n1+1], brr[n2+1], crr[n3+1], drr[n4+1];
+    akrr[n1]=10000000;
+    brr[n2]=100000000;
+    crr[n3]=100000000;
+   drr[n4]=1000000000;
+
+    for (int q = 0; q < n1; q++)
+    {
+        akrr[q] = arr[start + q];
+
+    }
+    for (int q = 0; q < n2; q++)
+    {
+        brr[q] = arr[mid1 + q+1];
+
+    }
+    for (int q = 0; q < n3; q++)
+    {
+        crr[q] = arr[mid + q+1];
+
+    }
+    for (int q = 0; q < n4; q++)
+    {
+        drr[q] = arr[mid2 + q+1];
+
+    }
+
+    int w = 0, h = 0;
+    int z = 0, y = 0, f = start;
+    while (w <= n1 && h <=n2 && z <=n3 && y <= n4 && f<=end)
+    {
+        if (akrr[w] < brr[h] && akrr[w] < crr[z] && akrr[w] < drr[y])
+        {
+            arr[f] = akrr[w];
+
+            w++;
+            f++;
+
+        }
+         else if ( brr[h] < crr[z] && brr[h] <drr[y])
+        {
+            arr[f] = brr[h];
+            h++;
+            f++;
+        }
+       else  if (crr[z] < drr[y])
+        {
+            arr[f] = crr[z];
+            z++;
+            f++;
+        }
+        else 
+        {
+            arr[f] = drr[y];
+            y++;
+            f++;
+        }
+
+    }
+
+}
+void mergesort(int arr[], int start, int end)
+{ 
+
+    if (start < end)
+    {
+
+     int mid=(start+end)/2;
+     int mid1= (start+mid)/2;////half of start and mid
+     int mid2=(mid+1+end)/2;; ////half of mid and end;
+
+        mergesort(arr, start, mid1);
+        mergesort(arr, mid1+1 , mid);
+        mergesort(arr, mid+1, mid2);
+        mergesort(arr, mid2+1, end);
+        merge(arr,start,mid1,mid,mid2,end);
+    }
+}
+
+int main()
+{
+    int arr[] = {5,4,3,2,1,6,7,23,21,22,87,90,276};
+    cout << "before sorted array";
+    for (int i = 0; i <4; i++)
+    {
+        cout << arr[i]<<endl;
+    }
+    mergesort(arr, 0, 12);
+    cout << "after sort"<<endl;;
+
+    for (int i = 0; i <13; i++)
+    {
+        cout << arr[i] << " ";
+    }
+    return 0;
+}