线索二叉树的结构实现

这个弄了好久，最主要理解中序遍历各节点的lchild指向左孩子还是前驱

和rchild指向右孩子还是后继，

还有线索化前的初始化和线索好之后的初始化（不知道这么说对不对，毕竟初学），

可以看看小甲鱼的视频，讲解的很不错，

上代码，前序输入就行，看代码自行了解输入规则，

#include<cstdio>
#include<cstring>
#include<cstdlib>

typedef enum {
	Link,Thread
}PointerTag;

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

BiThrTree pre;
void CreateThrTree(BiThrTree *T){
	char c;
	scanf("%c",&c);
	if(‘ ‘ == c){
		(*T) = NULL;
	}else{
		*T = (BiThrTree)malloc(sizeof(BiThrNode));
		(*T)->data = c;
		(*T)->LTag = Link;
		(*T)->RTag = Link;
		CreateThrTree(&(*T)->lchild);
		CreateThrTree(&(*T)->rchild);
	}
}
void InThreading(BiThrTree T){
	if(T){
		InThreading(T->lchild);
		if(T->lchild == NULL){
			T->LTag = Thread;
			T->lchild = pre;
		}
		if(pre->rchild == NULL){
			pre->RTag = Thread;
			pre->rchild = T;
		}
		pre = T;
		InThreading(T->rchild);
	}
}
void InOrderThreading(BiThrTree *p,BiThrTree T){
	*p = (BiThrTree)malloc(sizeof(BiThrNode));
	(*p)->LTag = Link;
	(*p)->RTag = Thread;
	(*p)->rchild = *p;
	if(!T){
		(*p)->lchild = *p;
	}else{
		(*p)->lchild = T;
		pre = *p;

		InThreading(T);
		pre->rchild = *p;
		pre->RTag = Thread;
		(*p)->rchild = pre;
	}
}
void OnOrderTraverse(BiThrTree T){
	BiThrTree p;
	p = T->lchild;
	while(p != T){
		while(p->LTag == Link){
			p = p->lchild;
		}
		printf("%c\n",p->data);
		while(p->RTag == Thread && p->rchild != T){
			p = p->rchild;
			printf("%c\n",p->data);
		}
		p = p->rchild;
	}

}
int main(){
	BiThrTree p,T;

	CreateThrTree(&T);

	InOrderThreading(&p,T);

	OnOrderTraverse(p);
//	InThreading(T);
	return 0;
}