Demo Programs

Creating & Using Queues

The following demo program shows how to create and perform operations on a circular array-based queue.

src/pydsa/queue/circ_array_queue.py

q = CircArrayQueue[int](4, 'int')

print(f"element type: '{q.element_type}'")

for x in (3, 1, 4, 1, 5):
    q.enqueue(x)

print(q)

for x in q:
    print(f'{x} ', end='')
print()

while not q.empty:
    print(f'dequeue: front = {q.front()} | size = {len(q)}')
    q.dequeue()

print(q, f'(queue is empty: {q.empty})')

To run the demo:

$ python src/pydsa/queue/circ_array_queue.py

Output:

element type: 'int'
[3,1,4,1,5]
3 1 4 1 5 
dequeue: front = 3 | size = 5
dequeue: front = 1 | size = 4
dequeue: front = 4 | size = 3
dequeue: front = 1 | size = 2
dequeue: front = 5 | size = 1
[] (queue is empty: True)

See Also : src/pydsa/queue/linked_list_queue.py is a similar demo program using the linked list based implementation instead.

Merging Two Queues

The following demo program shows how to perform a stable-merge of two (circular array-based) queues in which the element values imply the priority given when queues are merged. In the first part, the larger the value, the higher the priority (hence the use of operator.gt as argument compare). In the second part, the smaller the value, the higher the priority (hence the use of operator.lt as argument compare).

src/pydsa/queue/algo/merge.py

from operator import lt, gt
from pydsa.queue import CircArrayQueue

tests = (
    # larger the value, higher the priority given when merged
    ((4, 7, 2, 10), (3, 6, 8, 9, 5, 1), int, 'int', gt),
    # smaller the value, higher the priority given when merged
    ((4, 7, 2, 10), (3, 6, 8, 9, 5, 1), int, 'int', lt)
)

for nums1, nums2, t, t_name, cmp in tests:
    print(f'compare: {cmp}')
    q1 = CircArrayQueue[t](len(nums1), t_name)
    for num in nums1:
        q1.enqueue(num)
    print(f'q1     : {q1}')

    q2 = CircArrayQueue[t](len(nums2), t_name)
    for num in nums2:
        q2.enqueue(num)
    print(f'q2     : {q2}')

    print('merging q1 and q2...')
    merged = merge(q1, q2, cmp)
    print(f'merged : {merged}')
    print()

To run the demo:

$ python src/pydsa/queue/algo/merge.py

Output:

compare: <built-in function gt>
q1     : [4,7,2,10]
q2     : [3,6,8,9,5,1]
merging q1 and q2...
merged : [4,7,3,6,8,9,5,2,10,1]

compare: <built-in function lt>
q1     : [4,7,2,10]
q2     : [3,6,8,9,5,1]
merging q1 and q2...
merged : [3,4,6,7,2,8,9,5,1,10]