题目：

题解：

struct ListNode* swapPairs(struct ListNode* head) {struct ListNode dummyHead;dummyHead.next = head;struct ListNode* temp = &dummyHead;while (temp->next != NULL && temp->next->next != NULL) {struct ListNode* node1 = temp->next;struct ListNode* node2 = temp->next->next;temp->next = node2;node1->next = node2->next;node2->next = node1;temp = node1;}return dummyHead.next;
}