from typing import Optional
class Node:
def __init__(self, data: str, next=None):
self.data = data
self._next = next
class linkedQueue:
def __init__(self):
self._head: Optional[Node] = None
self._tail: Optional[Node] = None
def enqueue(self, value: str):
new_node = Node(value)
if self._tail:
self._tail._next = new_node
else:
self._head = new_node
self._tail = new_node
def dequeue(self) -> Optional[str]:
if self._head:
value = self._head.data
self._head = self._head._next
if not self._head:
self._tail = None
return value
def __repr__(self) -> str:
values = []
current = self._head
while current:
values.append(current.data)
current = current._next
return "->".join(value for value in values)
if __name__ == "__main__":
q = linkedQueue()
for i in range(10):
q.enqueue(str(i))
print(q)
for _ in range(3):
q.dequeue()
print(q)
q.enqueue("7")
q.enqueue("8")
print(q)
