c++ 建立链表并实现合并

创建两个链表并实现两个链表相加:

#include 
using namespace std;
struct ListNode{
	int val;
	ListNode *next;
	ListNode (int x):val(x),next(NULL){}
};

ListNode * Creat_Link()
{
	ListNode *head=NULL,*s,*r;
	int n;
	cin>>n;
	while(n!=-1)
	{
		s=new ListNode(n);
		if(head==NULL)
		  head=s;
		else
		  r->next=s;
		r=s;
		cin>>n;
	}
	r->next=NULL;
	return head;
}

ListNode *addTwoLink(ListNode *l1,ListNode *l2)
{
	ListNode *head=NULL,*s,*r;
	while(l1!=NULL&&l2!=NULL)
	{
		s=new ListNode(l1->val+l2->val);
		if(head==NULL)
		  head=s;
		else
		  r->next=s;
		r=s;
		l1=l1->next;
		l2=l2->next;
	}
	r->next=NULL;
	return head;
}

void display(ListNode *head)
{
	while(head!=NULL)
	{
		cout<val<<" ";
		head=head->next;
	}
	cout<