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 nullptr;
        }
        ListNode* nhead = new ListNode(0);
        
        ListNode* pre = pHead;
        while (pHead) {
            pHead = pHead->next;
            pre->next = nhead->next;
            nhead->next = pre;
            pre = pHead; 
        }
        return nhead->next;
    }
};