leetcode: 24. Swap Nodes in Pairs

原题链接

class Solution {
public:
    ListNode* swapPairs(ListNode* head) {
        ListNode* dummyHead = new ListNode();
        dummyHead->next = head;
        ListNode* cur = dummyHead;

        // 正常模拟即可，一定要画个图才清晰
        while (cur->next != nullptr && cur->next->next != nullptr) {
            ListNode* tmp = cur->next;
            ListNode* tmp1 = cur->next->next->next;

            cur->next = cur->next->next;
            cur->next->next = tmp;
            tmp->next->next->next = tmp1;

            cur = cur->next->next;
        }
        return dummyHead->next;
    }
};