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Python: heap queue algorithm - Exercises, Practice, Solution

Python heap queue algorithm [19 exercises with solution ]

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Heaps are binary trees for which every parent node has a value less than or equal to any of its children.
Here are some exercises of heap queue algorithm.

Python heap queue algorithm: heap queue pictorial.

1. Write a Python program to find the three largest integers from a given list of numbers using Heap queue algorithm. Go to the editor

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2. Write a Python program to find the three smallest integers from a given list of numbers using Heap queue algorithm. Go to the editor

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3. Write a Python program to implement a heapsort by pushing all values onto a heap and then popping off the smallest values one at a time. Go to the editor

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4. Write a Python function which accepts an arbitrary list and converts it to a heap using Heap queue algorithm. Go to the editor

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5. Write a Python program to delete the smallest element from the given Heap and then inserts a new item. Go to the editor

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6. Write a Python program to sort a given list of elements in ascending order using Heap queue algorithm. Go to the editor

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7. Write a Python program to find the kth (1 <= k <= array's length) largest element in an unsorted array using Heap queue algorithm. Go to the editor

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8. Write a Python program to compute maximum product of three numbers of a given array of integers using Heap queue algorithm. Go to the editor

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9. Write a Python program to find the top k integers that occur the most frequently from a given lists of sorted and distinct integers using Heap queue algorithm. Go to the editor

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10. Write a Python program to get the n expensive and cheap price items from a given dataset using Heap queue algorithm. Go to the editor

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11. Write a Python program to merge multiple sorted inputs into a single sorted iterator (over the sorted values) using Heap queue algorithm. Go to the editor

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12. Given a n x n matrix where each of the rows and columns are sorted in ascending order, write a Python program to find the kth smallest element in the matrix. Go to the editor

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13. Write a Python program to find the nth super ugly number from a given prime list of size k using Heap queue algorithm. Go to the editor

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14. Write a Python program to get the k most frequent elements from a given non-empty list of words using Heap queue algorithm. Go to the editor

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15. Write a Python program to check if the letters of a given string can be rearranged so that two characters that are adjacent to each other are different using Heap queue algorithm. Go to the editor

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16. Write a Python program which add integer numbers from the data stream to a heapq and compute the median of all elements. Use Heap queue algorithm. Go to the editor

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17. You are given two integer arrays sorted in ascending order and an integer k. Write a Python program to find k number of pairs (u, v) which consists of one element from the first array and one element from the second array using Heap queue algorithm. Go to the editor

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18. Write a Python program to find the nth ugly number using Heap queue algorithm. Go to the editor

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19. Write a Python program to print a heap as a tree-like data structure. Go to the editor

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Python Code Editor:

More to Come !

Do not submit any solution of the above exercises at here, if you want to contribute go to the appropriate exercise page.



Python: Tips of the Day

Python: How to install pip on Windows?

Python 2.7.9+ and 3.4+

Good news! Python 3.4 (released March 2014) and Python 2.7.9 (released December 2014) ship with Pip. This is the best feature of any Python release. It makes the community's wealth of libraries accessible to everyone. Newbies are no longer excluded from using community libraries by the prohibitive difficulty of setup. In shipping with a package manager, Python joins Ruby, Node.js, Haskell, Perl, Go-almost every other contemporary language with a majority open-source community. Thank you, Python.

If you do find that pip is not available when using Python 3.4+ or Python 2.7.9+, simply execute e.g.:

py -3 -m ensurepip

Of course, that doesn't mean Python packaging is problem solved. The experience remains frustrating. I discuss this in the Stack Overflow question Does Python have a package/module management system?.

And, alas for everyone using Python 2.7.8 or earlier (a sizable portion of the community). There's no plan to ship Pip to you. Manual instructions follow.

Python 2 = 2.7.8 and Python 3 = 3.3

Flying in the face of its 'batteries included' motto, Python ships without a package manager. To make matters worse, Pip was-until recently-ironically difficult to install.

Official instructions

Per https://pip.pypa.io/en/stable/installing/#do-i-need-to-install-pip:

Download get-pip.py, being careful to save it as a .py file rather than .txt. Then, run it from the command prompt:

python get-pip.py

You possibly need an administrator command prompt to do this. Follow Start a Command Prompt as an Administrator (Microsoft TechNet).

This installs the pip package, which (in Windows) contains ...\Scripts\pip.exe that path must be in PATH environment variable to use pip from the command line (see the second part of 'Alternative Instructions' for adding it to your PATH,

Alternative instructions

The official documentation tells users to install Pip and each of its dependencies from source. That's tedious for the experienced and prohibitively difficult for newbies.

For our sake, Christoph Gohlke prepares Windows installers (.msi) for popular Python packages. He builds installers for all Python versions, both 32 and 64 bit. You need to:

  1. Install setuptools
  2. Install pip

For me, this installed Pip at C:\Python27\Scripts\pip.exe. Find pip.exe on your computer, then add its folder (for example, C:\Python27\Scripts) to your path (Start / Edit environment variables). Now you should be able to run pip from the command line. Try installing a package:

pip install httpie

There you go (hopefully)! Solutions for common problems are given below:

Proxy problems

If you work in an office, you might be behind an HTTP proxy. If so, set the environment variables http_proxy and https_proxy. Most Python applications (and other free software) respect these. Example syntax:

http://proxy_url:port
http://username:[email protected]_url:port

If you're really unlucky, your proxy might be a Microsoft NTLM proxy. Free software can't cope. The only solution is to install a free software friendly proxy that forwards to the nasty proxy. http://cntlm.sourceforge.net/

Unable to find vcvarsall.bat

Python modules can be partly written in C or C++. Pip tries to compile from source. If you don't have a C/C++ compiler installed and configured, you'll see this cryptic error message.

Error: Unable to find vcvarsall.bat

You can fix that by installing a C++ compiler such as MinGW or Visual C++. Microsoft actually ships one specifically for use with Python. Or try Microsoft Visual C++ Compiler for Python 2.7.

Often though it's easier to check Christoph's site for your package.

Ref: https://bit.ly/2B0ch3y