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Python: Create a heapsort, pushing all values onto a heap and then popping off the smallest values one at a time

Python heap queue algorithm: Exercise-24 with Solution

Write a Python program to create a heapsort, pushing all values onto a heap and then popping off the smallest values one at a time.

Sample Solution:

Python Code:

import heapq
def heapsort(h):
    heap = []
    for value in h:
        heapq.heappush(heap, value)
    return [heapq.heappop(heap) for i in range(len(heap))]

print(heapsort([10, 20, 50, 70, 90, 20, 50, 40, 60, 80, 100]))

Sample Output:

[10, 20, 20, 40, 50, 50, 60, 70, 80, 90, 100]

Flowchart:

Python heap queue algorithm: Create a heapsort, pushing all values onto a heap and then popping off the smallest values one at a time.

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Python: Tips of the Day

Find current directory and file's directory:

To get the full path to the directory a Python file is contained in, write this in that file:

import os 
dir_path = os.path.dirname(os.path.realpath(__file__))

(Note that the incantation above won't work if you've already used os.chdir() to change your current working directory, since the value of the __file__ constant is relative to the current working directory and is not changed by an os.chdir() call.)

To get the current working directory use

import os
cwd = os.getcwd()

Documentation references for the modules, constants and functions used above:

  • The os and os.path modules.
  • The __file__ constant
  • os.path.realpath(path) (returns "the canonical path of the specified filename, eliminating any symbolic links encountered in the path")
  • os.path.dirname(path) (returns "the directory name of pathname path")
  • os.getcwd() (returns "a string representing the current working directory")
  • os.chdir(path) ("change the current working directory to path")

Ref: https://bit.ly/3fy0R6m