Merge pull request xtaci#8 from xmuliang/master

add heap sort

Author: xtaci

include/heap_sort.h

@@ -0,0 +1,58 @@
+/*******************************************************************************
+ * DANIEL'S ALGORITHM IMPLEMENTAIONS
+ *
+ *  /\  |  _   _  ._ o _|_ |_  ._ _   _
+ * /--\ | (_| (_) |  |  |_ | | | | | _>
+ *         _|
+ *
+ * HEAPSORT
+ *
+ * Features:
+ * 1. Although somewhat slower in practice on most machines than a well-implemented quicksort,
+      it has the advantage of a more favorable worst-case O(n log n) runtime
+ *
+ * http://en.wikipedia.org/wiki/Heapsort
+ *
+ ******************************************************************************/
+
+#ifndef __HEAPSORT_H__
+#define __HEAPSORT_H__
+
+#include <heap.h>
+
+namespace alg
+{
+
+
+	/**
+	 * heap sort an array
+	 */
+	template<typename T>
+	static void heapsort(T *array,int number_of_elements)
+	{
+		Heap<T> heap(number_of_elements);
+		int i;
+
+		/*In order to build a heap structure from input array*/
+		for(i=0;i<number_of_elements;i++)
+		{
+            heap.insert(array[i],0);    //set key with the value of the array,value to 0(no use)
+		}
+
+        /*Temporary array to store the minkey of each step,which is deleted from the heap*/
+		T tempArray[number_of_elements];
+		for(i=0;i<number_of_elements;i++)
+		{
+            tempArray[i]=heap.min_key();    //find the min key
+            heap.delete_min();
+		}
+
+		for(i=0;i<number_of_elements;i++)
+		{
+            array[i]=tempArray[i];      //copy back to the original array
+		}
+	}
+}
+
+#endif //
+

src/heap_sort_demo.cpp

@@ -0,0 +1,34 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+#include "generic.h"
+#include "heap_sort.h"
+
+using namespace alg;
+
+int main()
+{
+	const int MAX_ELEMENTS = 10;
+	int list[MAX_ELEMENTS];
+
+	int i = 0;
+
+	srand(time(NULL));
+	// generate random numbers and fill them to the list
+	for(i = 0; i < MAX_ELEMENTS; i++ ){
+		list[i] = rand()%100;
+	}
+	printf("The list before sorting is:\n");
+	printlist(list,MAX_ELEMENTS);
+
+	// sort the list using heap sort
+	heapsort<int>(&list[0],MAX_ELEMENTS);
+
+	// print the result
+	printf("The list after sorting using heapsort algorithm:\n");
+	printlist(list,MAX_ELEMENTS);
+	return 0;
+}
+
+