class Node:
def __init__(self, value, next=None):
self.value = value
self.next = next
class Queue:
def __init__(self):
self.head = None
self.tail = None
self.length = 0
def peek(self):
return self.head.value
def enqueue(self, value):
if self.isEmpty():
newNode = Node(value)
self.tail = newNode
self.head = newNode
else:
newNode = Node(value)
self.tail.next = newNode
self.tail = newNode
self.length+=1
def dequeue(self):
if self.isEmpty():
raise Exception("Queue is empty.")
elif self.head == self.tail:
returnVal = self.head.value
self.head = None
self.tail = None
else:
returnVal = self.head.value
self.head = self.head.next
self.length-=1
return returnVal
def isEmpty(self):
return (True if self.length == 0 else False)
print("Hello World!")
myQueue = Queue()
print(myQueue.isEmpty())
assert(myQueue.isEmpty() == True)
myQueue.enqueue("Jason")
myQueue.enqueue("Joseph")
assert(myQueue.isEmpty() == False)
myQueue.enqueue("Caroline")
assert(myQueue.peek()=="Jason")
print(myQueue.dequeue())
assert(myQueue.peek()=="Joseph")
print(myQueue.dequeue())
assert(myQueue.peek()=="Caroline")
print(myQueue.dequeue())
assert(myQueue.isEmpty() == True)
try:
print(myQueue.dequeue())
except Exception as e:
print(f"exception: {e}")
print("Goodbye Cruel World")
