Simple Solution in C++

[moytrage]

class Solution {
public:
    ListNode* mergeTwoLists(ListNode* l1, ListNode* l2) {
        ListNode * result = 0;
        ListNode ** result_ref = &result;
        while (l1 && l2) {
            if (l1->val < l2->val) {
                *result_ref = l1;
                l1 = l1->next;
            } else {
                *result_ref = l2;
                l2 = l2->next;
            }
            result_ref = &(*result_ref)->next;
        }
        if (l1) *result_ref = l1;
        else if (l2) *result_ref = l2;
        return result;
    }
};