题目信息
问题解答
https://leetcode-cn.com/submissions/detail/118746750/
function swapPairs(head: ListNode | null): ListNode | null {
const dummyHead = new ListNode()
dummyHead.next = head
let pre = dummyHead
while(head && head.next) {
let next = head.next
//完成一次交换
head.next = next.next
next.next = head
pre.next = next
pre = head
head = head.next
}
return dummyHead.next
};