updates with different pivot - clrs

Author: ashish-3916

recursion 2/quick sort code

@@ -1,41 +1,82 @@
-void swap(int *a,int *b)
+
+void swap(int *a, int *b)
+{
+	int temp = *a;
+	*a = *b;
+	*b = temp;
+}
+int p_front_cn(int a[], int l , int h )// equal to the left
+{
+	int pivot = a[l];
+	int count = 0;
+	for (int i = l + 1 ; i <= h; i++)
+	{if (a[i] <= pivot) count++; }
+
+	swap(&a[l], &a[l + count]);
+	pivot = a[l + count];
+	int i = l ; int j = l + count + 1;
+	while (i < l + count && j <= h)
+	{
+		if (a[i] <= pivot)i++;
+		else if (a[j] > pivot)j++;
+		else
+		{
+			swap ( &a[i] , &a[j]); i++ ; j++;
+		}
+	}
+	return l + count;
+}
+int p_back_clrs(int a[],  int l , int h)
 {
-    int temp=*a;
-     *a=*b;
-   *b=temp;
+	int pivot = a[h];
+	int i = l - 1;
+	for (int j = l ; j < h ; j++)
+	{
+		if (a[j] < pivot)
+		{
+			i++;
+			swap(&a[j], &a[i]);
+		}
+	}
+	swap(&a[h], &a[i + 1]);
+	return i + 1;
 }
+int p_front_clrs(int a[] , int l , int h)
+{
+	int pivot = a[l];
+
+	int i = h + 1;
+
+	for (int j = h; j > l ; j--)
+	{
+		if (a[j] > pivot)
+		{
+			i--;
+			swap(&a[j], &a[i]);
+		}
+	}
+	swap(&a[l] , &a[i - 1]);
+	return i - 1;
 
-int partition (int arr[], int low, int high) 
-{ 
-	int pivot = arr[high]; // pivot 
-	int i = (low - 1); // Index of smaller element 
-
-	for (int j = low; j <= high - 1; j++) 
-	{ 
-		// If current element is smaller than the pivot 
-		if (arr[j] < pivot) 
-		{ 
-			i++; // increment index of smaller element 
-			swap(&arr[i], &arr[j]); 
-		} 
-	} 
-	swap(&arr[i + 1], &arr[high]); 
-	return (i + 1); 
-} 
-void QuickSort(int a[],int s,int e)
+}
+void QuickSort(int a[], int s, int e)
 {
-    if(s>=e)
-        return;
-    int p=partition(a,s,e);
-    QuickSort(a,s,p-1);
-    QuickSort(a,p+1,e);
+	if (s >= e)
+		return;
+	 //int p = p_front_cn(a, s, e);
+	//int p = p_front_clrs(a, s, e);
+	int p = p_back_clrs(a, s, e);
+
+	QuickSort(a, s, p - 1);
+	QuickSort(a, p + 1, e);
+
 
 }
 void quickSort(int input[], int size) {
 
-    int start = 0;
-    int end = size-1;
+	int start = 0;
+	int end = size - 1;
 
-    QuickSort(input,start,end);
+	QuickSort(input, start, end);
 
 }