线索二叉树的建立与遍历

#include
#include
typedef char ElemType;
typedef struct BiTNode {
	ElemType data;
	struct BiTNode* lchild, * rchild;
	int ltag, rtag;
}ThreadNode,*ThreadTree;
void InThread(ThreadTree &p, ThreadTree &pre) {//二叉树线索化	
	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 T) {
	ThreadNode* pre;
	pre = NULL;
	if (T != NULL) {
		
		InThread(T,pre);
		pre->rchild = NULL;//处理最后一个节点
		pre->rtag = 1;
	}
}
void Creat(ThreadTree &T) {
	ElemType x;
	scanf_s("%c", &x);
	if (x =='#') {
		T = NULL;
		return ;
	}
	else {
		T = (ThreadTree)malloc(sizeof(ThreadNode));
		T->data = x;
		T->ltag = 0;
		T->rtag = 0;
		Creat(T->lchild);
		Creat(T->rchild);
	}
}
ThreadTree FirstNode(ThreadTree p) {//找到最左下的节点
	while(p->ltag == 0) {
		p = p->lchild;
	}
	return p;
}
ThreadTree NextNode(ThreadTree p) {//找到后继结点
	if (p->rtag == 0) {
		return FirstNode(p->rchild);
	}
	else
		return p->rchild;//若如果是线索，直接返回
}
void InOrder1(ThreadTree T) {//中序遍历线索二叉树
	
	for (ThreadTree p = FirstNode(T); p != NULL; p = NextNode(p)) {
		printf("%c", p->data);
	}
}
void PreOrder(ThreadTree T) {
	if (T == NULL)
		return;
	else {
		printf("%c", T->data);
		PreOrder(T->lchild);
		PreOrder(T->rchild);
	}
}
void InOrder(ThreadTree T) {
	if (T == NULL)
		return;
	else {
		
		InOrder(T->lchild);
		printf("%c", T->data);
		InOrder(T->rchild);
	}
}
void PostOrder(ThreadTree T) {
	if (T == NULL)
		return;
	else {

		PostOrder(T->lchild);
		
		PostOrder(T->rchild);
		printf("%c", T->data);
	}
}
int main() {
	ThreadTree T;
	Creat(T);
	printf("递归前序遍历：\n");
	PreOrder(T);
	printf("递归中序遍历：\n");
	InOrder(T);
	printf("\n");
	printf("递归后序遍历：\n");
	PostOrder(T);
	CreateInThread(T);
	printf("线索二叉树的遍历：\n");
	InOrder1(T);

	
}
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