链式存储结构实现队列

链式存储结构实现队列，即使用链表来存储队列中的元素。队列的头部和尾部分别对应链表的头结点和尾结点，入队操作相当于在链表尾部插入一个新结点，出队操作相当于删除链表头部的结点。下面是链式存储结构实现队列的具体实现方法：

1.定义队列结点类

class Node:
    def __init__(self, data):
        self.data = data
        self.next = None

2.定义队列类

class Queue:
    def __init__(self):
        self.head = None
        self.tail = None

    def is_empty(self):
        return self.head is None

    def enqueue(self, data):
        new_node = Node(data)
        if self.is_empty():
            self.head = new_node
            self.tail = new_node
        else:
            self.tail.next = new_node
            self.tail = new_node

    def dequeue(self):
        if self.is_empty():
            raise Exception("Queue is empty")
        else:
            data = self.head.data
            self.head = self.head.next
            if self.head is None:
                self.tail = None
            return data

    def size(self):
        count = 0
        current = self.head
        while current is not None:
            count += 1
            current = current.next
        return count

3.测试代码

q = Queue()
q.enqueue(1)
q.enqueue(2)
q.enqueue(3)
print(q.dequeue()) # 输出：1
print(q.dequeue()) # 输出：2
print(q.size()) # 输出：1