编辑“︁队列结构”︁（章节）

== 队列的实现 ==
队列可以通过数组或链表实现。以下是两种常见的实现方式：

=== 数组实现 ===
使用数组实现队列时，需要维护两个指针：`front` 和 `rear`，分别指向队首和队尾。为了避免空间浪费，可以使用'''循环队列'''（Circular Queue）。

<syntaxhighlight lang="python">
class Queue:
    def __init__(self, capacity):
        self.capacity = capacity
        self.queue = [None] * capacity
        self.front = 0
        self.rear = -1
        self.size = 0

    def is_empty(self):
        return self.size == 0

    def is_full(self):
        return self.size == self.capacity

    def enqueue(self, item):
        if self.is_full():
            raise Exception("Queue is full")
        self.rear = (self.rear + 1) % self.capacity
        self.queue[self.rear] = item
        self.size += 1

    def dequeue(self):
        if self.is_empty():
            raise Exception("Queue is empty")
        item = self.queue[self.front]
        self.front = (self.front + 1) % self.capacity
        self.size -= 1
        return item

    def peek(self):
        if self.is_empty():
            raise Exception("Queue is empty")
        return self.queue[self.front]
</syntaxhighlight>

'''示例输入与输出：'''
<syntaxhighlight lang="python">
q = Queue(3)
q.enqueue(10)
q.enqueue(20)
q.enqueue(30)
print(q.dequeue())  # 输出: 10
print(q.peek())     # 输出: 20
</syntaxhighlight>

=== 链表实现 ===
链表实现队列更加灵活，无需预先分配固定大小的空间。

<syntaxhighlight lang="python">
class Node:
    def __init__(self, data):
        self.data = data
        self.next = None

class LinkedListQueue:
    def __init__(self):
        self.front = None
        self.rear = None

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

    def enqueue(self, item):
        new_node = Node(item)
        if self.rear is None:
            self.front = self.rear = new_node
            return
        self.rear.next = new_node
        self.rear = new_node

    def dequeue(self):
        if self.is_empty():
            raise Exception("Queue is empty")
        item = self.front.data
        self.front = self.front.next
        if self.front is None:
            self.rear = None
        return item

    def peek(self):
        if self.is_empty():
            raise Exception("Queue is empty")
        return self.front.data
</syntaxhighlight>

'''示例输入与输出：'''
<syntaxhighlight lang="python">
q = LinkedListQueue()
q.enqueue("A")
q.enqueue("B")
q.enqueue("C")
print(q.dequeue())  # 输出: "A"
print(q.peek())     # 输出: "B"
</syntaxhighlight>