LeetCode题组：第21题-合并两个有序链表

struct ListNode{
	int val;
	struct ListNode *next;
};

struct ListNode* mergeTwoLists(struct ListNode* l1, struct ListNode* l2){
    struct ListNode* tmp;    //1号标记点
    struct ListNode header;  //1号标记点
    header.next=l1;
    l1=&header;
    while(l2!=0){
        while(l1->next!=0&&l1->next->val<l2->val) l1=l1->next;
        tmp=l2;
        l2=l2->next;
        tmp->next=l1->next;
        l1->next=tmp;
    }
    return header.next;
}

struct ListNode* tmp;   
struct ListNode header;