关于线索二叉树建立和遍历

#include <stdio.h>
#include <stdlib.h>

typedef struct ThreadNode {
	char data;
	struct ThreadNode *lchild, *rchild;
	int ltag, rtag;			//0为孩子，1为线索
}ThreadNode,*ThreadTree;

ThreadTree PreCreatebiTree(ThreadTree p,bool isroot) {			//先序创建二叉树
	char ch;
	if (isroot)
		printf("root: ");
	fflush(stdin);
	scanf("%c", &ch);
	fflush(stdin);		//清空缓存区,确保不影响后面的数据读取（例如在读完一个字符串后紧接着又要读取一个字符，此时应该先执行fflush(stdin))
	getchar();			//etchar()去掉回车
	if (ch != '#') {
		isroot = false;
		p = (ThreadNode*)malloc(sizeof(ThreadNode));
		p->data = ch;
		p->lchild = NULL;
		p->rchild = NULL;
		p->ltag = 0;
		p->rtag = 0;
		printf("%c's left child is: ", p->data);
		p->lchild=PreCreatebiTree(p->lchild,isroot);
		printf("%c's right child is: ", p->data);
		p->rchild=PreCreatebiTree(p->rchild,isroot);
	}
	return p;
} 

void PrebiTree(ThreadTree T) {					//先序遍历二叉树
	if (T != NULL) {
		printf("%c %d %d\n", T->data, T->ltag, T->rtag);
		PrebiTree(T->lchild);
		PrebiTree(T->rchild);
	}
}

void InThread(ThreadNode *p, ThreadNode *&pre) {	//中序线索递归 p引用不引用一样
	if (p != NULL) {
		InThread(p->lchild, pre);
		if (p->lchild == NULL) {
			p->lchild = pre;
			p->ltag = 1;
		}
		if (pre!=NULL&&pre->rchild == NULL) {
			pre->rchild = p;
			pre->rtag = 1;
		}
		pre = p;
		InThread(p->rchild, pre);
	}
}

void CreateInThread(ThreadTree p) {				//二叉树中序线索化
	ThreadNode *pre = NULL;
	if (p != NULL) {
		InThread(p, pre);
		pre->rchild = NULL;
		pre->rtag = 1;
	}
}

ThreadNode *FirstNode(ThreadNode *p) {			//当前根结点点中序序列下第一个结点
	if (p == NULL) {
		return NULL;
	}
	while (p->ltag == 0)
		p = p->lchild;
	return p;
}

ThreadNode *LastNode(ThreadNode *p) {			//当前根结点点中序序列下最后一个结点
	if (p == NULL) {
		return NULL;
	}
	while (p->rtag == 0)
		p = p->rchild;
	return p;
}

ThreadNode *NextNode(ThreadNode *p) {			//当前结点后继
	if (p == NULL) {
		return NULL;
	}
	if (p->rtag == 0)
		return FirstNode(p->rchild);
	return p->rchild;
}

ThreadNode *PreNode(ThreadNode *p) {			//当前结点前驱
	if (p == NULL) {
		return NULL;
	}
	if (p->ltag == 0)
		return LastNode(p->lchild);
	return p->lchild;
}

void InOrder(ThreadTree T) {				//中序遍历
	ThreadNode *p=NULL;
	for (p = FirstNode(T); p != NULL; p = NextNode(p))
		printf("%c %d %d\n", p->data, p->ltag, p->rtag);
}				//

void RevInOrder(ThreadTree T) {				//逆向中序遍历
	ThreadNode *p = NULL;
	for(p=LastNode(T);p!=NULL;p=PreNode(p))
		printf("%c %d %d\n", p->data, p->ltag, p->rtag);
}

int main() {
	ThreadTree T=NULL;
	T=PreCreatebiTree(T,1);
	PrebiTree(T);
	printf("\nbiTree create done\n");
	CreateInThread(T);
	printf("InOrder\n");
	InOrder(T);
	printf("RevInOrder:\n");
	RevInOrder(T);
	getchar();
	return 0;
}