typedef enum PointerTag{Link,Thread};
typedef struct{
char ch;
int num;
}ElemType;
typedef struct{
BiThrNode *lchild,*rchild;
PointerTag Ltag,Rtag;
ElemType data;
}BiThrNode,*BiThree;
//中序遍历记录线索二叉树
void InThreading(BiThree &p,BiThree &pre){
if(p){
InThreading(p->lchild,pre);
if(!(p->lchild)){
p->lchild=pre;
p->Ltag=Thread;
}
if(!(pre->rchild)){
pre->Rtag=Thread;
pre->rchild=p;
}
pre=p;
InThreading(p->rchild,pre);
}
}
//创建一个完整的线索二叉树
int InorderThreading(BiThree &Thr,BiThree &T){
BiThrNode *p,*pre;
if(!Thr=(BiThree)malloc(sizeof(BiThrNode))) exit(1);
Thr->rchild=Thr;
Thr->Rtag=Thread;
pre=Thr;
if(!T){Thr->lchild=Thr;exit(1);}
Thr->lchild=T;
p=T;
InThreading(p,pre);
pre->rchild=Thr;
pre->Rtag=Thread;
Thr->rchild=pre;
return 0;
}
//非递归中序遍历线索二叉树。
int InOrderTraverse_Thr(BiThree &T){
if(!T) exit(1);
BiThrNode *p=T->lchild;
while(p!=T){
while(p->Ltag==Link)p=p->lchild;
if(visit(p)) return 1;
while(p->Rtag==Thread&&p->rchild!=T)
{
p=p->rchild;
visit(p->rchild);
}
p=p->rchild;
}
return 0;
}