heap sort

heap.py

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+# Python program for implementation of heap Sort 
+
+# To heapify subtree rooted at index i. 
+# n is size of heap 
+def heapify(arr, n, i): 
+	largest = i # Initialize largest as root 
+	l = 2 * i + 1	 # left = 2*i + 1 
+	r = 2 * i + 2	 # right = 2*i + 2 
+
+	# See if left child of root exists and is 
+	# greater than root 
+	if l < n and arr[i] < arr[l]: 
+		largest = l 
+
+	# See if right child of root exists and is 
+	# greater than root 
+	if r < n and arr[largest] < arr[r]: 
+		largest = r 
+
+	# Change root, if needed 
+	if largest != i: 
+		arr[i],arr[largest] = arr[largest],arr[i] # swap 
+
+		# Heapify the root. 
+		heapify(arr, n, largest) 
+
+# The main function to sort an array of given size 
+def heapSort(arr): 
+	n = len(arr) 
+
+	# Build a maxheap. 
+	for i in range(n, -1, -1): 
+		heapify(arr, n, i) 
+
+	# One by one extract elements 
+	for i in range(n-1, 0, -1): 
+		arr[i], arr[0] = arr[0], arr[i] # swap 
+		heapify(arr, i, 0) 
+
+# Driver code to test above 
+arr = [ 12, 11, 13, 5, 6, 7] 
+heapSort(arr) 
+n = len(arr) 
+print ("Sorted array is") 
+for i in range(n): 
+	print ("%d" %arr[i]), 
+# This code is contributed by Mohit Kumra