剑指offer 十三题 在O(1)时间删除链表结点

#include<iostream>
#include<stdlib.h>
using namespace std;
struct ListNode
{
	int m_nValue;
	ListNode *m_pNext;
	ListNode(int n){ m_nValue = n; m_pNext = NULL; }
	
};
void DeleteNode(ListNode ** pListHead, ListNode * pToBeDeleted)
{
	if (!pListHead || !pToBeDeleted)
		return;
	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;
	}
	else if (*pListHead == pToBeDeleted)
	{
		delete pToBeDeleted;
		pToBeDeleted = NULL;
		pListHead = NULL;
	}
	else
	{
		ListNode *pNode = *pListHead;
		while (pNode->m_pNext != pToBeDeleted)
		{
			pNode = pNode->m_pNext;
		}
		pNode->m_pNext = NULL;
		delete pToBeDeleted;
		pToBeDeleted = NULL;
	}

}
int main()
{
	struct ListNode *pListHead, *p, *q, *t;
	int i, n, a;
	ListNode * a1 = new ListNode(5);
	ListNode * a2 = new ListNode(6);
	ListNode * a3 = new ListNode(7);
	ListNode * a4 = new ListNode(8);
	a1->m_pNext = a2;
	a2->m_pNext = a3;
	a3->m_pNext = a4;
	t = a1;
	while (t != NULL)
	{
		cout << t->m_nValue << " ";
		t = t->m_pNext;

	}
	cout << endl;
	DeleteNode(&a1,a3);
	t = a1;
	while (t != NULL)
	{
		cout << t->m_nValue<<" ";
		t = t->m_pNext;

	}
	system("pause");
	

}