Merge_Two_Sorted_Lists.cc

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode *mergeTwoLists(ListNode *l1, ListNode *l2) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        ListNode *ret = NULL;
        ListNode **pCur = &ret;
        while (l1 && l2) {
            if (l1->val < l2->val) {
                *pCur = l1;
                l1 = l1->next;
            } else {
                *pCur = l2;
                l2 = l2->next;
            }
            pCur = &((*pCur)->next);
        }
        *pCur = (l1 == NULL) ? l2 : l1;
        return ret;
    }
};