每日一题(8) - 求链表的中间结点

题目来自剑指Offer

题目

分析

代码

ListNode* FindMidNode(ListNode* pHead)
{
	assert(pHead != NULL);
	ListNode* pFast = pHead;
	ListNode* pSlow = pHead;
	while (pFast->m_pNext && pFast->m_pNext->m_pNext)
	{
		pFast = pFast->m_pNext->m_pNext;
		pSlow = pSlow->m_pNext;
	}
	return pSlow;
}

测试代码

#include <iostream>
#include <assert.h>
using namespace std;

struct ListNode
{
	int m_Data;
	ListNode* m_pNext;
};

ListNode* FindMidNode(ListNode* pHead)
{
	assert(pHead != NULL);
	ListNode* pFast = pHead;
	ListNode* pSlow = pHead;
	while (pFast->m_pNext && pFast->m_pNext->m_pNext)
	{
		pFast = pFast->m_pNext->m_pNext;
		pSlow = pSlow->m_pNext;
	}
	return pSlow;
}

void CreateList(ListNode** pHead,int nLen)//头指针使用指针的指针
{
	assert(*pHead == NULL && nLen > 0);
	ListNode* pCur = NULL;
	ListNode* pNewNode = NULL;
	for (int i = 0;i < nLen;i++)
	{
		pNewNode = new ListNode;
		cin>>pNewNode->m_Data;
		pNewNode->m_pNext = NULL;

		if (*pHead == NULL)
		{
			*pHead = pNewNode;
			pCur = *pHead;
		}
		else
		{
			pCur->m_pNext = pNewNode;
			pCur = pNewNode;
		}
	}
}

void PrintList(ListNode* pCurNode)
{
	assert(pCurNode != NULL);  
	while (pCurNode)  
	{  
		cout<<pCurNode->m_Data<<" ";  
		pCurNode = pCurNode->m_pNext;  
	}  
	cout<<endl;
}

int main()
{
	int nLen = 0;
	ListNode* pHead = NULL;
	ListNode* pMidNode = NULL;

	cout<<"please input node num: ";
	cin >> nLen;
	CreateList(&pHead,nLen);//注意传参使用引用
	PrintList(pHead);
	pMidNode = FindMidNode(pHead);
	cout<<"MidNode: "<<pMidNode->m_Data<<endl;
	system("pause");
	return 1;
}