LintCode:两两交换链表中的节点

LintCode:两两交换链表中的节点

/** * Definition for singly-linked list. * struct ListNode { *     int val; *     ListNode *next; *     ListNode(int x) : val(x), next(NULL) {} * }; */class Solution {public:    /**     * @param head a ListNode     * @return a ListNode     */    ListNode* swapPairs(ListNode* head) {        // Write your code here        if(head==NULL) return head;        ListNode* p = head;        while(p != NULL && p->next != NULL){            int tmp = p->val;            p->val = p->next->val;            p->next->val = tmp;            p = p->next->next;        }        return head;    }};