Part 3 Digital Images You will not only learn to program C i

Part 3: Digital Images You will not only learn to program C++ in this class, we will also show you some other things. One of these things is the plain PGM image file format. You will be working with this image format in this class. First, read this short introduction (doc version) to digital image s and the PGM image format. Many applications have PGM support built-in. Unfortunately, neither Windows nor Mac OS X currently come with an app which can display PGM images. On Windows, you can download IrfanView if you need a viewer. It is highly recommended that you have a program to view these files. For Macs, MacOS Sierra has finally added support for PGM images to the all-purpose viewer Preview, but you can also use ToyViewer (available free on the App store), which I find convenient for image viewing. For Irfanview, uncheck \"Use Resample for fitting\" and \"Use Resample for zooming\" under \"View | Display Options\". Otherwise (by default) Irfanview blurs images when you zoom them. That\'s great for general image viewing, but awkward for programmers rying to figure out what their program just wrote out to a PGM ile. The complete specification for the PGM format can be found on the netpbm website (look for plain PGM) or in Wikipedia Portable Pixmap. A plain PGM file is just a simple text file that follows the following standard nan

Solution

import heapq

# This is our priority queue implementation

class PriorityQueue:

def __init__(self):

self._queue = []

self._index = 0

def push(self, item, priority):

heapq.heappush(self._queue, (priority, self._index, item))

self._index += 1

def pop(self):

if(self._index == 0):

return None

return heapq.heappop(self._queue)[-1];