contributed

sorting/heap_sort.c

@@ -0,0 +1,65 @@
+#include<stdio.h>
+
+void create(int []);
+void down_adjust(int [],int);
+
+void main()
+{
+	int heap[30],n,i,last,temp;
+	printf("Enter no. of elements:");
+	scanf("%d",&n);
+	printf("\nEnter elements:");
+	for(i=1;i<=n;i++)
+		scanf("%d",&heap[i]);
+
+	//create a heap
+	heap[0]=n;
+	create(heap);
+
+	//sorting
+	while(heap[0] > 1)
+	{
+		//swap heap[1] and heap[last]
+		last=heap[0];
+		temp=heap[1];
+		heap[1]=heap[last];
+		heap[last]=temp;
+		heap[0]--;
+		down_adjust(heap,1);
+	}
+
+	//print sorted data
+	printf("\nArray after sorting:\n");
+	for(i=1;i<=n;i++)
+		printf("%d ",heap[i]);
+}
+
+void create(int heap[])
+{
+	int i,n;
+	n=heap[0]; //no. of elements
+	for(i=n/2;i>=1;i--)
+		down_adjust(heap,i);
+}
+
+void down_adjust(int heap[],int i)
+{
+	int j,temp,n,flag=1;
+	n=heap[0];
+
+	while(2*i<=n && flag==1)
+	{
+		j=2*i;	//j points to left child
+		if(j+1<=n && heap[j+1] > heap[j])
+			j=j+1;
+		if(heap[i] > heap[j])
+			flag=0;
+		else
+		{
+			temp=heap[i];
+			heap[i]=heap[j];
+			heap[j]=temp;
+			i=j;
+		}
+	}
+}