leetcode:Merge Two Sorted Lists（有序链表的归并）

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：思路比较简单，遍历两个有序链表，每次指向最小值。

code如下：

/**
 * 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) {
        ListNode *h = new ListNode(0), *p = h;
        while(l1 != NULL && l2 != NULL)
        {
            if(l1 -> val < l2 -> val)
            {
                p -> next = l1;
                l1 = l1 -> next;
            }
            else
            {
                p -> next = l2;
                l2 = l2 -> next;
            }
            p = p -> next;
        }
        if(l1 != NULL)
            p -> next = l1;
        if(l2 != NULL)
            p -> next = l2;
        return h -> next;
    }
};