Merge Two Sorted Lists

合并有序两个链表

class Solution {
public:
    ListNode *mergeTwoLists(ListNode *l1, ListNode *l2) {
        ListNode* res = new ListNode(0);
        if (l1 == NULL)
        {
            return l2;
        }
        else if (l2 == NULL)
        {
            return l1;
        }
        ListNode* head = res;
        int l1val = 0, l2val = 0;
        while (l1 != NULL&& l2!=NULL)
        {
            if (l1->val < l2->val)
            {
                head->next = l1;
                l1 = l1->next;
                head = head->next;
            }
            else
            {
                head->next = l2;
                l2 = l2->next;
                head = head->next;
            }
        }
        if (l1)
        {
            head->next = l1;
        }
        else
        {
            head->next = l2;
        }
        return res->next;
    }
};

来自为知笔记(Wiz)