From c454255604f8769db43a98e7870c0fde4eec6b05 Mon Sep 17 00:00:00 2001
From: Divya Gupta <38471510+divya144@users.noreply.github.com>
Date: Tue, 2 Oct 2018 22:56:20 +0530
Subject: [PATCH] Heap sort algorithm

This sorting algorithm sorts an array in ascending order in O(nlogn) time.
---
 sorting/heap_sort.cpp | 55 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 sorting/heap_sort.cpp

diff --git a/sorting/heap_sort.cpp b/sorting/heap_sort.cpp
new file mode 100644
index 00000000..6b61fd17
--- /dev/null
+++ b/sorting/heap_sort.cpp
@@ -0,0 +1,55 @@
+/*
+C++ implementation of heap sort
+Author:Divya Gupta
+Input:An array of integers
+Output: Gives an array sorted in ascending order
+Time Complexity:O(nlogn)
+*/
+#include<iostream>
+using namespace std;
+void swap(int* num1, int* num2) 
+{ 
+	int temp = *num1; 
+	*num1 = *num2; 
+	*num2 = temp; 
+}
+void heapify(int A[], int high, int low)
+{
+	int r = 2*low + 2; 
+    int largest = low;  
+    int l = 2*low + 1; 
+    if (l < high && A[l] > A[largest])
+        largest = l;
+   	if (r < high && A[r] > A[largest])
+       	largest = r;
+    if (largest != low)
+    {
+    	swap(&A[low],&A[largest]);
+    	heapify(A, high, largest);
+    }
+}
+void heapSort(int A[], int low, int high)
+{
+	for (int i = high / 2 - 1; i >= 0; i--)
+	    heapify(A, high, i);
+   	for (int i=high-1; i>=0; i--)
+   	{
+   	    swap(&A[0],&A[i]);
+   	    heapify(A, i, 0);
+   	}
+}
+
+int main()
+{
+    cout<<"Enter number of elements in an array"<<endl;
+    int n;
+    cin>>n; 
+    int a[n];
+    for(int i=0;i<n;i++)
+        cin>>a[i];
+    heapSort(a,0,n);
+    cout<<"Sorted array"<<endl;
+    for(int i=0;i<n;i++)
+        cout<<a[i]<<endl;
+}
+