题解 | #反转链表#

/*
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;
        pre = pHead, cur = pHead -> next;
        while (cur != nullptr){
            ListNode* tmp = cur -> next;//tmp用来保存原序列的下一个结点
            if (pre == pHead) pre -> next = nullptr;//及时将头结点next指向空防止循环链表
            cur -> next = pre;
            pre = cur;
            cur = tmp;
        }
        return pre;
    }
};