链表插入和显示

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

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

    def insert_at_head(self, data):
        new_node = Node(data)
        new_node.next = self.head
        self.head = new_node

    def insert_at_position(self, data, position):
        if position == 0:
            self.insert_at_head(data)
        else:
            new_node = Node(data)
            curr = self.head
            count = 0
            while curr and count < position - 1:
                curr = curr.next
                count += 1
            if curr:
                new_node.next = curr.next
                curr.next = new_node

    def display(self):
        curr = self.head
        while curr:
            print(curr.data, end=' ')
            curr = curr.next
        print()

# 创建链表并插入节点
linked_list = LinkedList()
linked_list.insert_at_head(3)
linked_list.insert_at_head(2)
linked_list.insert_at_head(1)
linked_list.insert_at_position(4, 2)

# 显示链表内容
linked_list.display()