[LeetCode]021-Merge Two Sorted Lists

最新推荐文章于 2022-05-22 13:07:29 发布

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本文提供了一种简单的方法来合并两个已排序的链表。通过比较两个链表中节点的值，将较小值的节点依次链接到新的链表中，最终形成一个完整的有序链表。

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题目：
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.

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Solution:
很简单，代码如下：

 ListNode* mergeTwoLists(ListNode* l1, ListNode* l2) 
    {
        if(l1 == NULL)
            return l2;
        if(l2 == NULL)
            return l1;
        ListNode * t1 = l1;
        ListNode * t2 = l2;

        ListNode * l3 = new ListNode(NULL);

        ListNode *head = l3;
        while(t1!=NULL && t2!=NULL)
        {
            if(t1->val < t2->val)
            {
                l3->val = t1->val;
                t1 = t1->next;
            }
            else
            {
                l3->val = t2->val;
                t2 = t2->next;
            }
            if(t1 != NULL && t2 !=NULL)
            {
                l3->next = new ListNode(NULL);
                l3 = l3->next;
            }
        }

        while(t1!=NULL)
        {
            l3->next = new ListNode(NULL);
            l3 = l3->next;
            l3->val = t1->val;

            t1 = t1->next;
        }

        while(t2!=NULL)
        {
            l3->next = new ListNode(NULL);
            l3 = l3->next;
            l3->val = t2->val;

            t2 = t2->next;
        }
        return head;
    }