00013

力扣 24 交换链表节点

class Solution:
    def swapPairs(self, head: Optional[ListNode]) -> Optional[ListNode]:
        dummy_head = ListNode(next = head)
        cur = dummy_head
        while cur.next and cur.next.next:
            temp = cur.next.next.next
            cur.next.next.next = cur.next
            cur.next = cur.next.next
            cur.next.next.next = temp            
            cur = cur.next.next
        return dummy_head.next