def test_peek():
stack = Stack()
stack.push(1)
stack.push(2)
actual = stack.peek()
expected = 2
assert actual == expected
def test_peek():
s = Stack()
s.push("apple")
s.push("banana")
actual = s.peek()
expected = "banana"
assert actual == expected
def test_check_not_empty():
s = Stack()
s.push("apple")
s.push("banana")
actual = s.is_empty()
expected = False
assert actual == expected
def test_peek_empty_exception():
stack = Stack()
stack.push(1)
stack.pop()
actual = stack.peek()
expected = "empty stack"
assert actual == expected
def test_peek():
test_stack = Stack()
test_stack.push(1)
test_stack.push(2)
test_stack.push(3)
assert test_stack.peek() == 3
def test_stack_pop():
testing_stack = Stack()
testing_stack.push(1)
testing_stack.push(2)
expected = 2
actual = testing_stack.peek()
assert actual == expected
def depth_first(self, starting_vertex):
"""
Method to do depth-first traversal on a graph.
Input: starting vertex
Output: list of vertices in the depth-first order
"""
vertices = []
depth = Stack()
if starting_vertex not in self._adjacency_list:
raise ValueError
depth.push(starting_vertex)
while not depth.is_empty():
top_vertex = depth.pop()
vertices.append(top_vertex.value)
top_node_neighbors = self.get_neighbors(top_vertex)
for neighbor in top_node_neighbors[::-1]:
if not neighbor[0].visited:
top_vertex.visited = True
neighbor[0].visited = True
depth.push(neighbor[0])
for node in self._adjacency_list:
node.visited = False
return vertices
def test_mult_pop_stack():
stack = Stack()
stack.push('1')
stack.push('2')
stack.pop()
stack.pop()
assert stack.is_empty() == True
def test_pop_one():
stack = Stack()
stack.push(1)
stack.pop()
expected = None
actual = stack.peek()
assert actual == expected
def test_pop_to_empty():
stack = Stack()
stack.push(1)
stack.push(2)
stack.pop()
stack.pop()
assert stack.is_empty
def test_stack_peek():
"""Can successfully peek the next item on the stack.
"""
laundry = Stack()
laundry.push('socks')
laundry.push('jeans')
assert laundry.top.value == 'jeans'
def test_stack_push_multiple():
testing_stack = Stack()
testing_stack.push(1)
testing_stack.push(2)
testing_stack.push(3)
expected = 3
actual = testing_stack.peek()
assert actual == expected
def test_stack_pop_all_top():
colors = Stack()
colors.push('red')
colors.push('blue')
colors.pop()
colors.pop()
assert colors.top is None
def test_stack_pop_all_top():
hats = Stack()
hats.push('seahawks')
hats.push('gray')
hats.pop()
hats.pop()
assert hats.top is None
def test_stack_pop_until_empty():
s = Stack()
s.push('1')
s.push('2')
assert s.pop() == '2'
assert s.pop() == '1'
assert s.pop() == None
def test_push_multiple():
stack = Stack()
stack.push(1)
stack.push(2)
stack.push(3)
expected = 3
actual = stack.peek()
assert actual == expected
def test_stack_push_mult():
s = Stack()
s.push('1')
s.push('2')
s.push('3')
s.push('4')
assert s.top.value == '4'
def test_pop_off():
stack = Stack()
stack.push(1)
stack.push(2)
stack.pop()
expected = 1
actual = stack.peek()
assert actual == expected
def test_push_multiple():
stack = Stack()
stack.push('A')
stack.push('B')
stack.push('C')
expected = 'C'
actual = stack.peek()
assert expected == actual
def test_stack_push():
# STACK: push onto a stack
stack = Stack()
stack.push('pao de queijo')
actualBool, actualStr = stack.peek()
expectedBool, expectedStr = True, 'pao de queijo'
assert actualBool == expectedBool
assert actualStr == expectedStr
def test_pop():
test_stack = Stack()
test_stack.push(1)
test_stack.push(2)
test_stack.push(3)
popped = test_stack.pop()
assert popped == 3
assert test_stack.length == 2
assert test_stack.top.value == 2
class PseudoQueue(object):
# internal stack obj
_data = None
def __init__(self):
# create Stack for internal data-struct
self._data = Stack()
def count(self):
# pass through method to underlying data struct
# BigO == O(n)
return self._data.count()
def enqueue(self, val: str) -> bool:
# enqeue a value at the end queue
# BigO == O(1)
self._data.push(val)
return True
def dequeue(self) -> (str, bool):
# dequeue from head of queue
# BigO == O(n)
# Algo: use a second stack, as we need the bottom element on the first stack
# so we are going to unload the first stack, into a temp stack, in order to
# get at the bottom element of the first, then rebuild it from temp to first-stack
retStr = ''
retBool = False
# Empty List? Early return!
b, s = self._data.peek()
if not b:
return retStr, retBool
# reverse the primary stack into temp stack
tempStack = Stack()
while True:
b, s = self._data.peek()
if b == False:
break
val = self._data.pop()
tempStack.push(val)
# top element on tempstack is the bottom of the primary data stack
retStr = tempStack.pop()
# reverse the temp stack back to the primary stack
while True:
b, s = tempStack.peek()
if b == False:
break
val = tempStack.pop()
self._data.push(val)
return retStr, True
def stack_of_seven():
new_stack = Stack()
new_stack.push('One')
new_stack.push('Two')
new_stack.push('Three')
new_stack.push('Four')
new_stack.push('Five')
new_stack.push('Six')
new_stack.push('Seven')
return new_stack
def test_multipop():
test_stack = Stack()
test_stack.push(1)
test_stack.push(2)
test_stack.push(3)
test_stack.pop()
test_stack.pop()
test_stack.pop()
assert test_stack.length == 0
assert test_stack.bottom == None
def dequeue(self):
rev_stack = Stack()
while self.stack.top:
rev_stack.push(self.stack.pop())
removed = rev_stack.pop()
while rev_stack.top:
self.enqueue(rev_stack.pop())
return removed
def test_push():
"""Can successfully push a node on a stack.
"""
laundry = Stack()
laundry.push('socks')
expected = 'socks'
actual = laundry.top.value
assert expected == actual
def test_more_push():
new_stack = Stack()
new_stack.push('One')
new_stack.push('Two')
new_stack.push('Three')
new_stack.push('Four')
new_stack.push('Five')
new_stack.push('Six')
new_stack.push('Seven')
assert new_stack.top.value == 'Seven'
def test_stack_pop_many():
s = Stack()
s.push('1')
s.push('2')
s.push('3')
s.push('4')
assert s.pop() == '4'
assert s.pop() == '3'
assert s.pop() == '2'
assert s.pop() == '1'
def test_push():
"""Can successfully push multiple nodes on a stack.
"""
laundry = Stack()
laundry.push('socks')
laundry.push('jeans')
laundry.push('shirt')
expected = 'shirt'
actual = laundry.top.value
assert expected == actual
def test_two_pop():
"""Can successfully pop all items off a stack.
"""
laundry = Stack()
laundry.push('socks')
laundry.push('jeans')
laundry.push('shirt')
expected = 'socks'
actual = laundry.pop_all()
assert expected == actual