offer_24

//反转链表
ListNode* ReverseList(ListNode* pHead)
{
  ListNode* pReversedHead=nullptr;
  ListNode* pNode=pHead;
  ListNode* pPrev=nullptr;
  while(pNode!=nullptr){
    ListNode* pNext=pNode->m_pNext;
    if(pNext==nullptr)
      pReversedHead=pNode;
     
     pNode->m_pNext=pPrev;
     
     pPrev=pNode;
     pNode=pNext;
  }
  return pReversedHead;
}