def test_peek():
nums = Stack()
nums.top = Node(13)
actual = nums.peek()
expected = 13
assert actual == expected
def test_pop():
nums = Stack()
# Stand Alone testing:
nums.top = Node(1)
actual = nums.pop()
expected = 1
assert actual == expected
# Using methods from Stack class:
nums.push(100, 13)
actual = nums.pop()
expected = 13
assert actual == expected
def test_push_one_value():
nums = Stack()
nums.push(1)
assert nums.top.value == 1
def test_peek_on_empty_stack():
nums = Stack()
actual = nums.peek()
expected = 'Stack is empty'
assert actual == expected
def test_emptying_stack_with_multi_pop():
nums = Stack()
# Stand Alone testing:
nums.top = Node(1)
temp = nums.top
nums.top = Node(13)
nums.top.next = temp
nums.pop()
nums.pop()
actual = nums.pop()
expected = 'Stack is empty'
assert actual == expected
# Using methods from Stack class:
nums.push(100, 13)
nums.pop()
nums.pop()
actual = nums.pop()
expected = 'Stack is empty'
assert actual == expected
def test_create_empty_stack():
nums = Stack()
assert nums.top == None
def test_pop_from_empty_stack():
nums = Stack()
actual = nums.pop()
expected = 'Stack is empty'
assert actual == expected
def test_push_multiple_values():
nums = Stack()
nums.push(1, 3, 5, 9)
assert nums.top.value == 9
assert nums.__str__() == 'top->9->5->3->1-> NULL'
def __init__(self):
self.front_stack = Stack()
self.rear_stack = Stack()
self.len = 0
class PseudoQueue():
def __init__(self):
self.front_stack = Stack()
self.rear_stack = Stack()
self.len = 0
def enqueue(self, value):
"""
Push Node(value) to front_stack
"""
self.len += 1
self.front_stack.push(value)
def dequeue(self):
"""
Dequeue an item from the queue.
1) If both stacks are empty, return stack is empty.
2) If rear_stack is empty
While front_stack is not empty, push everything from front_stack to rear_stack.
3) Pop the element from rear_stack and return it.
"""
if self.rear_stack.isEmpty():
while self.len > 0:
self.rear_stack.push(self.front_stack.pop())
self.len -= 1
output = self.rear_stack.pop()
while True:
self.front_stack.push(self.rear_stack.pop())
self.len += 1
if self.rear_stack.isEmpty():
return output
else:
return "stack is empty!"
def __str__(self):
output = 'Rear ->'
if self.front_stack.isEmpty():
current = self.rear_stack.top
else:
current = self.front_stack.top
while current:
output += f"{{{current.value}}} -> "
current = current.next
output += " Front"
return output