查找单链表的中间节点，要求只能遍历一次链表

//查找单链表的中间节点，要求只能遍历一次链表
#include<iostream>
using namespace std;

#include<assert.h>

typedef int DataType;
typedef struct SListNode
{
DataType data;            //数据
struct SListNode * next;   //指向下一个结点的指针
}SListNode;

SListNode* CreateNode(DataType x)  //创造结点
{
//1.先开辟空间 2.数据赋给data 3.指针置空
SListNode* NewNode = (SListNode *)malloc(sizeof (SListNode));
NewNode->data = x;
NewNode->next = NULL;

return NewNode;
}

void PushBack(SListNode * &ppHead, DataType Data )
{
//1.none 2.one and more
if (ppHead == NULL)
{
ppHead = CreateNode(Data );
}
else
{
//1.先找到尾结点 2.把新节点链起来
SListNode* cur = ppHead ;
while (cur->next)
{
cur = cur->next;
}
cur->next = CreateNode( Data);

}
}
//打印
void PrintSNodeList(SListNode *&ppHead)
{
while (ppHead )
{
printf( "%d->", ppHead ->data);
ppHead = ppHead ->next;
}
cout << "NULL" << endl;
}

//查找单链表的中间节点，要求只能遍历一次链表
//快慢指针
SListNode* FindMidOneTime(SListNode * pHead)
{
assert(pHead != NULL);

SListNode* fast = pHead ;
SListNode* slow = pHead ;
while (fast)
{
if (fast->next)
{
fast = fast->next->next;
}
else
{
break;
}
slow = slow->next;
}
return slow;
}
void Test()
{
SListNode* pHead = NULL ;
PushBack(pHead, 1);
PushBack(pHead, 2);
PushBack(pHead, 3);
PushBack(pHead, 4);
PushBack(pHead, 5);
PushBack(pHead, 6);
PushBack(pHead, 7);
cout << FindMidOneTime(pHead)->data<< endl;
}
int main()
{
Test();
system( "pause");
return 0;
}