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| 1 | +# Python program for implementation of heap Sort |
| 2 | + |
| 3 | +# To heapify subtree rooted at index i. |
| 4 | +# n is size of heap |
| 5 | +def heapify(arr, n, i): |
| 6 | + largest = i # Initialize largest as root |
| 7 | + l = 2 * i + 1 # left = 2*i + 1 |
| 8 | + r = 2 * i + 2 # right = 2*i + 2 |
| 9 | + |
| 10 | + # See if left child of root exists and is |
| 11 | + # greater than root |
| 12 | + if l < n and arr[i] < arr[l]: |
| 13 | + largest = l |
| 14 | + |
| 15 | + # See if right child of root exists and is |
| 16 | + # greater than root |
| 17 | + if r < n and arr[largest] < arr[r]: |
| 18 | + largest = r |
| 19 | + |
| 20 | + # Change root, if needed |
| 21 | + if largest != i: |
| 22 | + arr[i],arr[largest] = arr[largest],arr[i] # swap |
| 23 | + |
| 24 | + # Heapify the root. |
| 25 | + heapify(arr, n, largest) |
| 26 | + |
| 27 | +# The main function to sort an array of given size |
| 28 | +def heapSort(arr): |
| 29 | + n = len(arr) |
| 30 | + |
| 31 | + # Build a maxheap. |
| 32 | + for i in range(n, -1, -1): |
| 33 | + heapify(arr, n, i) |
| 34 | + |
| 35 | + # One by one extract elements |
| 36 | + for i in range(n-1, 0, -1): |
| 37 | + arr[i], arr[0] = arr[0], arr[i] # swap |
| 38 | + heapify(arr, i, 0) |
| 39 | + |
| 40 | + |
| 41 | +# Driver code to test above |
| 42 | +arr = [ 12, 11, 13, 5, 6, 7] |
| 43 | +heapSort(arr) |
| 44 | +n = len(arr) |
| 45 | +print ("Sorted array is") |
| 46 | +for i in range(n): |
| 47 | + print ("%d" %arr[i]), |
| 48 | +# This code is contributed by Argho Chakraborty!!! |
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