Leetcode#21 Merge Two Sorted Lists

原题地址

链表归并排序的一个小函数

代码：

ListNode *mergeTwoLists(ListNode *l1, ListNode *l2) {
        ListNode *h = NULL;
        ListNode *t = NULL;
        
        while (l1 && l2) {
            ListNode *n = NULL;
            if (l1->val <= l2->val) {
                n = l1;
                l1 = l1->next;
            }
            else {
                n = l2;
                l2 = l2->next;
            }
            if (!h)
                h = t = n;
            else {
                t->next = n;
                t = t->next;
            }
        }
        
        while (l1) {
            if (!h)
                h = t = l1;
            else {
                t->next = l1;
                t = t->next;
            }
            l1 = l1->next;
        }
        
        while (l2) {
            if (!h)
                h = t = l2;
            else {
                t->next = l2;
                t = t->next;
            }
            l2 = l2->next;
        }
        
        return h;
}