按字母顺序将节点插入到链表中

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

def insert_node(head, data):
    new_node = Node(data)
    
    # 如果链表为空，将新节点设置为头节点
    if head is None:
        head = new_node
        return head
    
    # 如果要插入的数据小于头节点的数据，将新节点设置为头节点
    if data < head.data:
        new_node.next = head
        head = new_node
        return head
    
    # 遍历链表，找到插入位置
    current = head
    while current.next is not None and current.next.data < data:
        current = current.next
    
    # 插入新节点
    new_node.next = current.next
    current.next = new_node
    
    return head