From ccd24a9afdefec82ab9ca2c41a19a7d131822b74 Mon Sep 17 00:00:00 2001
From: Nitish <nitishchintakindi@gmail.com>
Date: Tue, 21 Feb 2023 11:43:35 +0530
Subject: [PATCH] Heap Sort code in C++ added with comments

---
 src/heap_sort_demo.cpp | 62 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100644 src/heap_sort_demo.cpp

diff --git a/src/heap_sort_demo.cpp b/src/heap_sort_demo.cpp
new file mode 100644
index 00000000..0b18bfb4
--- /dev/null
+++ b/src/heap_sort_demo.cpp
@@ -0,0 +1,62 @@
+#include<iostream>
+using namespace std;
+
+// Heap Sort by Heapify - Time Comp. -> O(N*logN)
+void printArr(int arr[], int n){
+
+	for(int i = 0; i < n; i++)
+		cout << arr[i] << " ";
+	cout << endl;
+}
+
+void heapify(int arr[], int n, int i){
+
+    int largest = i; // Initialize largest as root
+    int left = 2 * i + 1; // left = 2*i + 1
+    int right = 2 * i + 2; // right = 2*i + 2
+ 
+    // If left child is larger than root
+    if(left < n && arr[left] > arr[largest])
+        largest = left;
+ 
+    // If right child is larger than largest so far
+    if(right < n && arr[right] > arr[largest])
+        largest = right;
+ 
+    // If largest is not root
+    if(largest != i){
+
+        swap(arr[i], arr[largest]);
+        heapify(arr, n, largest); // Recursively heapify the affected sub-tree
+    }
+}
+
+void heapSort(int arr[], int n){
+
+	// Build heap (rearrange array)
+	for(int i = n/2 - 1; i >= 0; i--){
+		heapify(arr, n, i);
+	}
+	// One by one extract an element from heap
+	for(int i = n - 1; i >= 0; i--){
+
+		// Move current root to end
+		swap(arr[i], arr[0]);
+		// call max heapify on the reduced heap
+		heapify(arr, i, 0);
+	}
+}
+
+int main(){
+
+	int arr[5] = {54, 53, 55, 52, 50};
+	int n = sizeof(arr) / sizeof(arr[0]);
+
+	printArr(arr, n);
+
+	heapSort(arr, n);
+
+	printArr(arr, n);
+
+	return 0;
+}