Feedback on heaps, priority queues, and integer sorting algorithms

[Anisha7]

Great work on completing these challenges. Here's some feedback to improve your code:

• Try writing some tests for priority queues, or even just creating a simple priority queue at the bottom of your file. You'll notice that you get TypeError: insert() takes exactly 2 arguments. You're using your heap's insert method here, so check what parameters and in what order are given to this method.
• Your priority queue does not work as expected. Your front, push_pop, and dequeue functions should return the actual item! So if I inserted "apple" with priority 0, the item is "apple".
• Your counting sort does not account for the empty list case! You can't access index 0 of an empty list of numbers.

[Mintri1199]

• I fixed the bugs of my enqueue methods that was causing the problem.
• I've added the empty list case for my counting sort as well.

[Anisha7]

Try these tests for your priority queue to help you debug your push_pop() method:

if __name__ == '__main__':
    test_priority_queue()
    PQ = PriorityQueue()
    assert(PQ.is_empty())
    assert(PQ.length() == 0)
    PQ.enqueue("apple", 2)
    assert(PQ.length() == 1)
    assert(PQ.front() == "apple")
    assert(PQ.length() == 1)
    PQ.enqueue("orange", 0)
    assert(PQ.length() == 2)
    assert(PQ.front() == "orange")
    assert(PQ.length() == 2)
    assert(PQ.dequeue() == "orange")
    assert(PQ.length() == 1)
    assert(PQ.push_pop("banana", 4) == "apple")
    assert(PQ.length() == 1)
    assert(PQ.front() == "banana")
    assert(PQ.length() == 1)
    print("PASSED")

You need to return the item, not the tuple.

[Mintri1199]

Oh ok, sorry I overlooked it. I just needed to index the item in the tuple like so return self.heap.replace_min((priority, item))[1]