线索二叉树thread.cpp

数据结构经典课件(附带各章的经典算法) 具体代码是使用C语言编写的

#include <stdio.h>
#include <malloc.h>
#define MaxSize 100
typedef char ElemType;
typedef struct node 
{
	ElemType data;
	int ltag,rtag;     
	struct node *lchild;
	struct node *rchild;
} TBTNode;
void CreateTBTNode(TBTNode * &b,char *str)
{
	TBTNode *St[MaxSize],*p=NULL;
	int top=-1,k,j=0;  
	char ch;
	b=NULL;				
	ch=str[j];
	while (ch!='\0')
	{
   	   	switch(ch) 
		{
		case '(':top++;St[top]=p;k=1; break;		
		case ')':top--;break;
		case ',':k=2; break;                      	
		default:p=(TBTNode *)malloc(sizeof(TBTNode));
				p->data=ch;p->lchild=p->rchild=NULL;
		        if (b==NULL)					
					b=p;
				else  							
				{	
					switch(k) 
					{
					case 1:St[top]->lchild=p;break;
					case 2:St[top]->rchild=p;break;
					}
				}
		}
		j++;
		ch=str[j];
	}
}

TBTNode *pre;						
void Thread(TBTNode *&p)
{
	if (p!=NULL)	
	{	
		Thread(p->lchild);    		
		if (p->lchild==NULL)		
		{
			p->lchild=pre;        	
			p->ltag=1;
		}
		else p->ltag=0;
		if (pre->rchild==NULL)		
		{	
			pre->rchild=p;     		
		   	pre->rtag=1;
		}
		else pre->rtag=0;
	    pre=p;
	   	Thread(p->rchild);  		
	}
}
TBTNode *CreaThread(TBTNode *b)     /*中序线索化二叉树*/
{
	TBTNode *root;
	root=(TBTNode *)malloc(sizeof(TBTNode));  
	root->ltag=0;root->rtag=1;
	root->rchild=b;
	if (b==NULL)               
		root->lchild=root;
	else
	{  	
		root->lchild=b;
		pre=root;             	
		Thread(b);   			
		pre->rchild=root;    	
		pre->rtag=1;
		root->rchild=pre;    	
	}
    return root;
}
char disp[10];
int k;
void ThInOrder(TBTNode *tb)
{
	TBTNode *p=tb->lchild;		
	while (p!=tb)		
	{
		while (p->ltag==0) 
			p=p->lchild;
		disp[k]=p->data;k++;
		while (p->rtag==1 && p->rchild!=tb)
		{
			p=p->rchild;
			disp[k]=p->data;k++;
		}
		p=p->rchild;
	}
}
void main()
{
	TBTNode *b,*tb;
	CreateTBTNode(b,"A(B(D(,G)),C(E,F))");	
	tb=CreaThread(b);
	k=0;
	ThInOrder(tb);
}