Create heap sort.py

data_structures/heap sort.py

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+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+# 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.
+# Since last parent will be at ((n//2)-1) we can start at that location.
+
+	for i in range(n // 2 - 1, -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(arr[i])
+