LeetCode 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.

 

原地合并两个已经排序号的链。

 

代码：

/*******************************************************************
struct ListNode {
    int val;
    ListNode *next;
    ListNode(int x) : val(x), next(NULL) {}
};
*******************************************************************/
class Solution {
public:
    ListNode *mergeTwoLists(ListNode *l1, ListNode *l2) {
        ListNode *head=NULL,*ps;	//新的头，新链已经操作到的位置
		if(l1==NULL)
			return l2;
		if(l2==NULL)
			return l1;
		if(l1->val<l2->val)	//获取新头
		{
			head=l1;
			l1=l1->next;
		}
		else
		{
			head=l2;
			l2=l2->next;
		}
		ps=head;
		while(l1!=NULL||l2!=NULL)	//合并
		{
			if(l1==NULL)
			{
				ps->next=l2;
				break;
			}
			if(l2==NULL)
			{
				ps->next=l1;
				break;
			}
			if(l1->val<l2->val)
			{
				ps->next=l1;
				ps=l1;
				l1=l1->next;
			}
			else
			{
				ps->next=l2;
				ps=l2;
				l2=l2->next;
			}
		}
		return head;
    }
};