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;
    }
};