二叉树的非递归中序遍历（二叉线索存储结构）

 

# include 
# include 
# include 
# include 

# define OK   1
# define ERROR  0
# define OVERFLOW   -1

typedef char TElemType;
typedef enum PointerTag { Link, Thread };

typedef struct BiThrNode 
{
 TElemType data;
 struct BiThrNode *lchild, *rchild;
 PointerTag  LTag, RTag;
}BiThrNode,*BiThrTree;

BiThrTree pre;

void InThreading(BiThrTree p)
{
 if (p)
 {
  InThreading(p->lchild);
  
  if (!p->lchild)
  {
   p->LTag = Thread;
   p->lchild = pre;
  }

  if (! pre->rchild)
  {
   pre->RTag = Thread;
   pre->rchild = p;
  }

  pre = p;

  InThreading(p->rchild);
 }
}


int InOrderThreading(BiThrTree &Thrt, BiThrTree T)
{
 Thrt = (BiThrTree) malloc (sizeof (BiThrNode));

 if (!Thrt)
  exit (OVERFLOW);

 Thrt->LTag = Link;
 Thrt->RTag = Thread;
 Thrt->rchild = Thrt;

 if (!T)
  Thrt->lchild = Thrt;

 else
 {
  Thrt->lchild = T;
  pre = Thrt;
  InThreading(T);
  pre->rchild = Thrt;
  pre->RTag = Thread;
  Thrt->rchild = pre;
 }

 return OK;
}

int CreateBiThrTree(BiThrTree &T)
{
 TElemType ch;
 cin>>ch;
 if (ch == '#')
  T = NULL;

 else
 {
  T= (BiThrTree) malloc (sizeof (BiThrNode));
  T->data = ch;
  CreateBiThrTree(T->lchild);
  if (T->lchild)
   T->LTag = Link;

  CreateBiThrTree(T->rchild);
  if (T->rchild)
   T->RTag = Link;

 }

 return OK;
}

int InOrderTraverse_Thr(BiThrTree T,int (*Visit)(TElemType e))
{
 BiThrTree p;
 p = T->lchild ;
 while (p != T)
 {
  while (p->LTag == Link)
   p = p->lchild ;
  if (! Visit(p->data))
   return ERROR;

  while (p->RTag == Thread && p->rchild != T)
  {
   p = p->rchild ;
   Visit(p->data);
  }

  p = p->rchild ;
 }

 return OK;
}

int Print(TElemType e)
{
 cout<

结果图：