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heap.py
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# # Max-Heap data structure in Python
#
# def heapify(arr, n, i):
# largest = i
# l = 2 * i + 1
# r = 2 * i + 2
#
# if l < n and arr[l] > arr[largest]:
# largest = l
#
# if r < n and arr[r] > arr[largest]:
# largest = r
#
# if largest != i:
# arr[i], arr[largest] = arr[largest], arr[i]
# if i-1 >= 0:
# heapify(arr, n, (i-1)//2)
#
#
# def insert(array, newNum):
# size = len(array)
# if size == 0:
# array.append(newNum)
# else:
# array.append(newNum);
# size = len(array)
# heapify(array, size, (size//2)-1)
#
#
# def deleteNode(array, num):
# size = len(array)
# i = 0
# for i in range(0, size):
# if num == array[i]:
# break
#
# array[i], array[size - 1] = array[size - 1], array[i]
#
# array.remove(num)
#
# for i in range((len(array) // 2) - 1, -1, -1):
# heapify(array, len(array), i)
#
#
# arr = []
#
# insert(arr, 100)
# print("Max-Heap array: " + str(arr))
# insert(arr, 1)
# print("Max-Heap array: " + str(arr))
# insert(arr, 3)
# print("Max-Heap array: " + str(arr))
# insert(arr, 4)
# print("Max-Heap array: " + str(arr))
# insert(arr, 90)
# print("Max-Heap array: " + str(arr))
# insert(arr, 5)
# print("Max-Heap array: " + str(arr))
# insert(arr, 2)
# print("Max-Heap array: " + str(arr))
# insert(arr, 10)
# print("Max-Heap array: " + str(arr))
# insert(arr, 110)
# print("Max-Heap array: " + str(arr))
# insert(arr, 8)
# print("Max-Heap array: " + str(arr))
# insert(arr, 200)
# print("Max-Heap array: " + str(arr))
# insert(arr, 77)
# print("Max-Heap array: " + str(arr))
#
# deleteNode(arr, 4)
# print("After deleting an element: " + str(arr))
# 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[largest] < 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 // 2 - 1, -1, -1):
heapify(arr, n, i)
# One by one extract elements
for i in range(n - 1, 0, -1):
print(arr)
arr[i], arr[0] = arr[0], arr[i] # swap
heapify(arr, i, 0)
# Driver code
arr = [80, 100, 500, 10, 600, 700, 55, 1, 555]
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