/*
struct ListNode {
	int val;
	struct ListNode *next;
	ListNode(int x) :
			val(x), next(NULL) {
	}
};*/
class Solution {
public:
    ListNode* ReverseList(ListNode* pHead) {
        if(pHead == nullptr) return pHead;
        ListNode *pre,*cur,*next;
        pre = nullptr;
        cur = pHead;
        next = pHead->next;
        while(next)
        {
            cur->next = pre;
            pre = cur;
            cur = next;
            next = next->next; 
            
        }
        cur->next = pre;
        return cur;
    }
};