p62 练习3.3 通过只调整指针（而不是数据）来交换两个相邻的元素，使用：

由于两种数据结构的结点结构体都较为简单，这里就不列出了

a.单链表

List creatList1(List T,int n) //创建单链表 (头插法)

{

int x;Position S;

T = new struct Node;

T->Next = NULL;

for(int i = 0;i < n;i++)

{

S = new struct Node;

cin>>x;

S->Data = x;

S->Next = T->Next;

T->Next = S;

}

return T;

}

交换相邻结点算法：

void SwapAdjNode1(List T,Position P1,Position P2)

{

if(P1->Next!=P2)

{

cout<<"不是相邻结点";

return;

}

else

{

PtrToNode P0;

P0 = FindPrevious(P1->Data,T);

P1 = P2->Next;

P2->Next = P1;

P0->Next = P2;

return;

}

}

b:双链表

List creatList2(List T,int n) //创建双向链表

{

Position rear = T; //尾插法需要定义一个尾指针

Position S;

T = new struct Node;

T->Next= NULL;

T->prior = NULL;

for(int i = 0;i < n;i++)

{

S = new struct Node; //尾插法

cin>>S->Data;

rear->Next = S;

head->prior = S;

S->prior = rear;

S->Next = head;

rear = S;

}

return T;

}

交换相邻结点算法：

void SwapAdjNode2(List T,Position p1,Position p2)

{

 Position P0 = FindPrevious(p1->Data,List T); 

 Position P3 = p2->Next;

 if(P1->Next!=P2)

 {

  cout<<"不是相邻结点";

  return;

 }

 else

 {

  P0->Next = p2;

  p1->Next = p3;

  p1->prior = p2;

  p2->Next = p1;

  p2->prior = p0;

  p3->prior = p1;

 }
}

这里列出FindPreviou算法实现：

Position FindPrevious(DataType x,List T)  //寻找前置结点;

{

 PtrToNode p;

 p = T;

 while(p->Next!=NULL&&p->Next->Data!=x)

 {

  p = p->Next;

 }

 if(p->Next == NULL)

 {

  return NULL;

 }

 else return p;

}