[剑指offer][面试题13]在O(1)时间删除链表结点

给定链表的头指针和一个结点指针,在O(1)时间内删除该结点。

#include <iostream>using namespace std;struct Node{  int   m_Data;  Node *m_pNext;  };  /* Assumption the node to be deleted is in the list.* Given the head and the node pointers, try to delete the node in O(1) time.*/void deleteNodeFromList(Node **ppHead, Node *pNodeToBeDeleted){if (ppHead==NULL || *ppHead==NULL || pNodeToBeDeleted==NULL){return;}Node *pHead = *ppHead;//case1: the list contains only one node.if (pNodeToBeDeleted==pHead && pHead->m_pNext==NULL){delete pHead;*ppHead = NULL;return;}//case2. the list contains at least two nodes, and the node to be deleted is the last node.if (pNodeToBeDeleted->m_pNext==NULL){while (pHead->m_pNext!=pNodeToBeDeleted){pHead = pHead->m_pNext;}pHead->m_pNext = NULL;delete pNodeToBeDeleted;pNodeToBeDeleted = NULL;return;}//case3. the list contains at least two nodes, and the node to be deleted is not the last node.Node *pNext = pNodeToBeDeleted->m_pNext;pNodeToBeDeleted->m_Data = pNext->m_Data;pNodeToBeDeleted->m_pNext = pNext->m_pNext;delete pNext;pNext = NULL;}void printList(Node *pHead)  {  bool bEmpty = true;  while (pHead){  bEmpty = false;  cout<<pHead->m_Data<<"->";    pHead = pHead->m_pNext;  }  if (!bEmpty){  cout<<"NULL"<<endl;    }  } int main(){Node *pNode0 = new Node; pNode0->m_Data = 0;Node *pNode1 = new Node; pNode1->m_Data = 1;Node *pNode2 = new Node; pNode2->m_Data = 2;Node *pNode3 = new Node; pNode3->m_Data = 3;Node *pNode4 = new Node; pNode4->m_Data = 4;pNode0->m_pNext = pNode1;pNode1->m_pNext = pNode2;pNode2->m_pNext = pNode3;pNode3->m_pNext = pNode4;pNode4->m_pNext = NULL;Node **ppHead = &pNode0;printList(*ppHead);cout<<"\n delete node: "<<pNode0->m_Data<<endl;deleteNodeFromList(ppHead, pNode0);printList(*ppHead);cout<<"\n delete node: "<<pNode4->m_Data<<endl;deleteNodeFromList(ppHead, pNode4);printList(*ppHead);cout<<"\n delete node: "<<pNode2->m_Data<<endl;deleteNodeFromList(ppHead, pNode2);printList(*ppHead);}