天工造物局

21. Merge Two Sorted Lists
注：代码来自leetcode

struct ListNode* mergeTwoLists(struct ListNode* l1, struct ListNode* l2) {
    if(l1==NULL) return l2;
    if(l2==NULL) return l1;
    if(l1->val<l2->val)
    {
        l1->next=mergeTwoLists(l1->next,l2);
        return l1;
    }
    else
    {
        l2->next=mergeTwoLists(l1,l2->next);
        return l2;
    }
}