[Leetcode] Merge Two Sorted Lists

Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.

没啥好说的。

/**
 * 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) {
        ListNode *res;
        ListNode *p = new ListNode(0);
        res = p;
        while (l1 != NULL && l2 != NULL) {
            if (l1->val < l2->val) {
                p->next = l1;
                l1 = l1->next;
            } else {
                p->next = l2;
                l2 = l2->next;
            }
            p = p->next;
        }
        if (l1 != NULL) {
            p->next = l1;
        }
        if (l2 != NULL) {
            p->next = l2;
        }
        return res->next;
    }
};