13\给定单向链表的头指针和一个结点指针，定义一个函数在O（1）时间删除该结点，

<pre name="code" class="cpp">#include "List.h"
#include <stdio.h>
#include <stdlib.h>

ListNode* CreateListNode(int value)
{
ListNode* pNode = new ListNode();
pNode->m_nValue = value;
pNode->m_pNext = NULL;
return pNode;
}

void ConnectListNodes(ListNode* pCurrent, ListNode* pNext)
{
if(pCurrent == NULL)
{
printf("Error to connect two nodes.\n");
exit(1);
// exit(0)表示正常退出
// exit(1)表示异常退出.这个1是返回给操作系统的。
}
pCurrent->m_pNext = pNext;
}

void PrintListNode(ListNode* pNode)
{
if(pNode == NULL)
{
printf("The node is NULL\n");
}
else
{
printf("The key in node is %d.\n", pNode->m_nValue);
}
}

void PrintList(ListNode* pHead)
{
printf("PrintList starts.\n");
ListNode* pNode = pHead;
while(pNode != NULL)
{
printf("%d\t", pNode->m_nValue);
pNode = pNode->m_pNext;
}
printf("\n PrintList ends.\n");
}

void DestroyList(ListNode* pHead)
{
ListNode *pNode = pHead;
while(pNode != NULL)
{
pHead = pHead->m_pNext;
delete pNode;
pNode = pHead;
}
}

<pre name="code" class="cpp">/*
main Definition
Created by taotao man on 2015-11-10
brief: 给定单向链表的头指针和一个结点指针，定义一个函数在O（1）时间删除该结点，链表结点与函数的定义如下：
struct ListNode
{
int m_nValue;
ListNode *m_pNext;
};
void DeleteNode(ListNode **pListHead, ListNode * pToBeDeleted);
date: 2015-11-10
// 修改记录：
add SetA();
Change GetA();
*/

#include "stdafx.h"
#include "List.h"

void DeleteNode(ListNode **pListHead, ListNode * pToBeDeleted)
{
if(!pListHead || !pToBeDeleted)
return;
// 要删除的结点不是尾结点
if(pToBeDeleted->m_pNext != NULL)
{
ListNode *pNext = pToBeDeleted->m_pNext;
pToBeDeleted->m_nValue = pNext->m_nValue;
pToBeDeleted->m_pNext = pNext->m_pNext;

delete pNext;
pNext = NULL;
}
// 链表只有一个结点，删除头结点（也是尾结点）
else if(*pListHead == pToBeDeleted)
{
delete pToBeDeleted;
pToBeDeleted = NULL;
*pListHead = NULL;
}
// 链表中有多个结点，删除尾结点
else
{
ListNode *pNode = *pListHead;
while(pNode->m_pNext != pToBeDeleted)
{
pNode = pNode->m_pNext;
}
pNode->m_pNext = NULL;
delete pToBeDeleted;
pToBeDeleted = NULL;
}

}

// ====================测试代码====================
void Test(ListNode* pListHead, ListNode* pNode)
{
printf("The original list is: \n");
PrintList(pListHead);

printf("The node to be deleted is: \n");
PrintListNode(pNode);

DeleteNode(&pListHead, pNode);
printf("The result list is: \n");
PrintList(pListHead);
}

// 链表中有多个结点，删除中间的结点
void Test1()
{
ListNode* pNode1 = CreateListNode(1);
ListNode* pNode2 = CreateListNode(2);
ListNode* pNode3 = CreateListNode(3);
ListNode* pNode4 = CreateListNode(4);
ListNode* pNode5 = CreateListNode(5);

ConnectListNodes(pNode1, pNode2);
ConnectListNodes(pNode2, pNode3);
ConnectListNodes(pNode3, pNode4);
ConnectListNodes(pNode4, pNode5);
Test(pNode1, pNode3);

DestroyList(pNode1);
}

// 链表中有多个结点，删除尾结点
void Test2()
{
ListNode* pNode1 = CreateListNode(1);
ListNode* pNode2 = CreateListNode(2);
ListNode* pNode3 = CreateListNode(3);
ListNode* pNode4 = CreateListNode(4);
ListNode* pNode5 = CreateListNode(5);

ConnectListNodes(pNode1, pNode2);
ConnectListNodes(pNode2, pNode3);
ConnectListNodes(pNode3, pNode4);
ConnectListNodes(pNode4, pNode5);

Test(pNode1, pNode5);
DestroyList(pNode1);
}

// 链表中有多个结点，删除头结点
void Test3()
{
ListNode* pNode1 = CreateListNode(1);
ListNode* pNode2 = CreateListNode(2);
ListNode* pNode3 = CreateListNode(3);
ListNode* pNode4 = CreateListNode(4);
ListNode* pNode5 = CreateListNode(5);

ConnectListNodes(pNode1, pNode2);
ConnectListNodes(pNode2, pNode3);
ConnectListNodes(pNode3, pNode4);
ConnectListNodes(pNode4, pNode5);

Test(pNode1, pNode1);
DestroyList(pNode1);

}

// 链表中只有一个结点，删除头结点
void Test4()
{
ListNode* pNode1 = CreateListNode(1);

Test(pNode1, pNode1);
}

// 链表为空
void Test5()
{
Test(NULL, NULL);
}

int _tmain(int argv, _TCHAR* argc)
{
// Test1();
// Test2();
// Test3();
// Test4();
Test5();
return 0;
}