从方法获取链表中的位置

class ListNode:
    def __init__(self, val=0, next=None):
        self.val = val
        self.next = next

def get_position(head, target):
    position = 0
    current = head

    while current:
        if current.val == target:
            return position
        current = current.next
        position += 1

    return -1  # 目标元素不存在

# 示例用法
# 创建链表: 1 -> 2 -> 3 -> 4 -> 5
head = ListNode(1)
head.next = ListNode(2)
head.next.next = ListNode(3)
head.next.next.next = ListNode(4)
head.next.next.next.next = ListNode(5)

target = 3
position = get_position(head, target)
if position != -1:
    print(f"元素 {target} 的位置是 {position}")
else:
    print(f"元素 {target} 不存在于链表中")