Update Heap Sort.py

03_Sorting-Algorithms/Heap Sort.py

@@ -1,33 +1,46 @@
-def heapify(arr, n, i):
-	largest = i
-	l = 2 * i + 1 
-	r = 2 * i + 2 
-
-	if l < n and arr[i] < arr[l]:
-		largest = l
-
-	if r < n and arr[largest] < arr[r]:
-		largest = r
-
-	if largest != i:
-		(arr[i], arr[largest]) = (arr[largest], arr[i]) # swap
-
-		heapify(arr, n, largest)
-
-def heapSort(arr):
-	n = len(arr)
-
-	for i in range(n // 2 - 1, -1, -1):
-		heapify(arr, n, i)
-
-	for i in range(n - 1, 0, -1):
-		(arr[i], arr[0]) = (arr[0], arr[i]) # swap
-		heapify(arr, i, 0)
-
-arr = [12, 11, 13, 5, 6, 7, ]
-heapSort(arr)
-n = len(arr)
-print('Sorted array is')
-for i in range(n):
-	print(arr[i])
-
+# https://practice.geeksforgeeks.org/problems/heap-sort/1
+
+
+class Solution:
+
+    #Heapify function to maintain heap property.
+    def heapify(self,arr, n, i):
+        largest = i 
+        l = 2 * i + 1  
+        r = 2 * i + 2   
+
+        #if left or right child is greater than current element, 
+        #we store its position.
+        if l < n and arr[i] < arr[l]:
+            largest = l
+        if r < n and arr[largest] < arr[r]:
+            largest = r
+
+        #if largest is not equal to i, we swap the values at their position.     
+        if largest != i:
+            arr[i], arr[largest] = arr[largest], arr[i]
+            #calling function recursively for the largest variable.
+            self.heapify(arr, n, largest)
+
+
+    #Function to build a Heap from array.
+    def buildHeap(self,arr,n):
+
+        #calling heapify function for values from half to first index.
+        for i in range(n, -1, -1):
+            self.heapify(arr, n, i)
+
+    #Function to sort an array using Heap Sort.
+    def HeapSort(self,arr,n):
+
+        #calling function to build heap with array.
+        self.buildHeap(arr,n)
+
+        for i in range(n - 1, 0, -1):
+
+            #swapping values at current and first index.
+            arr[i], arr[0] = arr[0], arr[i] 
+            #calling heapify function for first index.
+            self.heapify(arr, i, 0)
+
+