学步园

以下例子演示逆转一个单向链表：

//// test in vc++8.0 xp

#include <iostream>
#include <cassert>

using namespace std;

struct Node
{
 int  item;
 Node* next;

 Node( int item_info, Node* pLink ) : item(item_info), next(pLink)
 {
 }
};

typedef  Node* Link;

// 逆转
Link ReverseList( Link beginLink )
{
 // 维护三个链接

 Link preLink;
 Link curLink;
 Link nextLink;

 preLink = NULL;
 curLink = beginLink;
 while ( curLink != NULL )
 {
  nextLink = curLink->next;
  curLink->next = preLink;
  preLink = curLink;
  curLink = nextLink;
 }

 return preLink;
}

// 创建
Link CreateSingleDirectionList( int nodeCount )
{
 Link pFirst = new Node( 1, NULL );
 Link pTempLink = pFirst;

 for ( int pos= 2; pos <= nodeCount; pos ++ )
 { 
  pTempLink = ( pTempLink->next = new Node( pos, NULL ) );
 }

 return pFirst;
}

// 销毁
void DestroySigleDirectionList( Link pFirst )
{
 assert( pFirst != NULL );
 if ( pFirst == NULL )
  return;

 for ( Link pTempLink = pFirst; pTempLink != NULL; )
 {
  Link pLinkNext = pTempLink->next;
  delete  pTempLink;

  pTempLink = pLinkNext;
 }
}

// test code
int _tmain(int argc, _TCHAR* argv[])
{
 // 创建单向链表
 Link pFirst = CreateSingleDirectionList( 20 );
 for ( Link pTempLink = pFirst; pTempLink != NULL; pTempLink = pTempLink->next )
 {
  cout << pTempLink->item << " ";
 }

 cout << endl << "after reverse:/n";

 // 逆向
 Link  pNewFirst = ReverseList( pFirst );
 for ( Link pTempLink = pNewFirst; pTempLink != NULL; pTempLink = pTempLink->next )
 {
  cout << pTempLink->item << " ";
 }
 cout << endl;

 DestroySigleDirectionList( pNewFirst );

 return 0;
}