实现为单链接的优先级队列在插入时更新指针引用失败

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

class PriorityQueue:
    def __init__(self):
        self.head = None

    def insert(self, value, priority):
        new_node = Node(value, priority)
        if not self.head or self.head.priority < priority:
            new_node.next = self.head
            self.head = new_node
        else:
            current = self.head
            while current.next and current.next.priority >= priority:
                current = current.next
            new_node.next = current.next
            current.next = new_node

# 使用示例
pq = PriorityQueue()
pq.insert("Task 1", 1)
pq.insert("Task 2", 5)
pq.insert("Task 3", 3)