单链表的逆转

单链表的逆转

 利用3个指针遍历单链表，逐个链接点进行反转。

/*
只需要完成逆置链表函数
struct ListNode
{
	int val;
	struct ListNode *next;
	ListNode(int x) :
	val(x), next(NULL) 
	{
	}
};
*/
class Solution 
{
	public:
	ListNode* ReverseList(ListNode* pHead)
	{
		if(pHead==NULL||pHead->next==NULL) return pHead;
		ListNode*p,*q,*r;
		p = pHead;    
		q = pHead->next;  
		pHead->next = NULL;

		while(q)
		{  
			r = q->next;
			q->next = p; 
			p = q;   
			q = r;   
		}  
		pHead=p; 
		return pHead;      
	}
};

参考：http://blog.youkuaiyun.com/feliciafay/article/details/6841115