LeetCode 0024 - Swap Nodes in Pairs

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* swapPairs(ListNode* head) {
        ListNode* travel = head;
        while(travel && travel->next){
            swap(travel->val, travel->next->val);
            travel = travel->next->next;
        }
        return head;
    }
};