LeetCode（21）Merge Two Sorted Lists

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.

分析

数据结构与算法的链表章节的典型实例，将两个有序链表合成一个，保持其有序的性质。

AC代码

/** * Definition for singly-linked list. * struct ListNode { *     int val; *     ListNode *next; *     ListNode(int x) : val(x), next(NULL) {} * }; */class Solution {public:    ListNode* mergeTwoLists(ListNode* l1, ListNode* l2) {        if (l1 == NULL)            return l2;        if (l2 == NULL)            return l1;        //合并后链表初始化为空        ListNode *rl = NULL;        ListNode *p = l1, *q = l2;        if (l1->val <= l2->val)        {            rl = l1;                        p = l1->next;        }        else{            rl = l2;            q = l2->next;        }        rl->next = NULL;        ListNode *head = rl;        while (p && q)        {            if (p->val <= q->val)            {                rl->next = p;                p = p->next;                            }            else{                rl->next = q;                q = q->next;            }//else            rl = rl ->next;        }//while        while (p)        {            rl->next = p;            p = p->next;            rl = rl->next;        }        while (q)        {            rl->next = q;            q = q->next;            rl = rl->next;        }        return head;    }};

GitHub测试程序源码