Merge pull request #3 from adithbharadwaj/sorting

added heapsort in sorting algorithms

Author: manishbisht

Algorithms/Sorting/heapSort.cpp

@@ -0,0 +1,99 @@
+
+// max heap inplementation using arrays without using dynamic resizing.
+
+// best case = worst case = avg case = o(nlogn);
+
+#include<iostream>
+
+#define maxsize 100
+
+using namespace std;
+
+// helper methods
+
+void swap(int *a, int *b){
+
+	int temp = *a;
+	*a = *b;
+	*b = temp;
+
+}
+
+// function to max_heapify the given array
+void max_heapify(int a[], int n, int i){
+
+	int max = i;
+	int l = 2 * i + 1; 
+	int r = 2 * i + 2;
+
+	if(l < n && a[l] > a[max]){
+	    max = l;
+	}
+	if(r < n && a[r] > a[max]){
+	    max = r;
+	}
+	 
+	if(max != i){
+	    swap(&a[i], &a[max]);
+	    max_heapify(a, n, max);
+	}
+	   
+   
+}
+
+
+// delete min element and return it
+
+int heapSort(int a[], int n){
+
+	for (int i = n/2 - 1; i >= 0; i--){
+
+		max_heapify(a, n, i);
+
+	}
+
+	for (int i = n - 1; i >= 0; i--){
+
+		swap(&a[0], &a[i]);
+
+		max_heapify(a, i, 0);
+
+	}
+	  
+	   
+	for (int i = 0; i < n; i++){
+
+		cout << a[i] << endl;
+
+	}
+
+}
+
+int main(){
+
+   	int n, el;
+
+   	cout << "Enter the size of the array: " << endl;
+   	cin >> n;
+    
+    int a[n];
+
+   	cout << "Enter the elements" << endl;  
+   
+   	for (int i = 0; i < n; i++) {
+   	   
+   		cin >> a[i];
+
+   	}
+
+   	cout << endl;
+
+	// heapsort
+
+	cout << "The sorted elements are: " << endl;
+
+	heapSort(a, n);  
+
+	return 0;
+
+}