遍历二叉数

（1）递归的方式递归二叉数

#include <stdio.h>

#include <stdlib.h>



typedef struct node

{

	char data;

	struct node *lchild;

	struct node *rchild;

}Node;



void creatBT(Node* T)

{

	char ch;

	scanf("%c", &ch);



	if ('.'==ch)

	{

		return;

	}

	else

	{

		T=(Node *)malloc(sizeof(Node));

		if (T==NULL)

		{

			exit(0);

		}

		T->data=ch;

		creatBT(T->lchild);

		creatBT(T->rchild);

	}

}



void pre_order(Node* T)

{

	if (T)

	{

		printf("%c ", T->data);

		pre_order(T->lchild);

		pre_order(T->rchild);

	}

}



void mid_order(Node* T)

{

	if (T)

	{

		pre_order(T->lchild);

		printf("%c ", T->data);

		pre_order(T->rchild);

	}

}



void behind_order(Node* T)

{

	if (T)

	{

		pre_order(T->lchild);

		pre_order(T->rchild);

		printf("%c ", T->data);

	}

}



int main()

{

	Node *T;  

	printf("请输按先序序列输入一串字符,当子树为空时, 用.来代替\n");  

	/* 创建二叉数 */

	creatBT(T);

	printf("建树成功,T指向二叉树的根!\n"); 

	

	/* 前序遍历*/

	printf("\n前序遍历二叉树的结果是:");  

	pre_order(T);

	

	/* 中序遍历*/

	printf("\n中序遍历二叉树的结果是:");  

	mid_order(T); 

	

	/* 后序遍历*/

	printf("\n后序遍历二叉树的结果是:");  

	behind_order(T);printf("\n");  



	return 0;  

}

 （2）非递归遍历二叉数

#include <iostream>

using namespace std;



typedef struct node            

{

	char data;

	struct node* lchild;

	struct node* rchild;

}bintnode;

 

typedef struct stack  

{

	bintnode* data[100];          

	int tag[100];               

	int top;                    

}seqstack;



void push(seqstack* s,bintnode* t) 

{

	s->data[s->top]=t;

	++s->top;

}



bintnode* pop(seqstack* s)            

{

	if(s->top!=-1)              

	{

		s->top--;

		return (s->data[s->top+1]);

	}

	else 

	return NULL;

}



void createbintree(bintnode* t)   

{

	char ch;

	if((ch=getchar())=='.')

	{

		t=NULL;

	}

	else

	{

		t=(bintnode*)malloc(sizeof(bintnode));   

		t->data=ch;

		createbintree(t->lchild);            

		createbintree(t->rchild);             

	}

}



void preorder(bintnode* t)

{

	seqstack s;

	s.top=-1;                            

	while((t)||(s.top!=-1))              

	{

		while(t)

		{

			cout<<t->data<<"  ";         

			s.top++;

			s.data[s.top]=t;             

			t=t->lchild;                 

		}                                

		if(s.top>-1)

		{

			t=pop(&s);                  

			t=t->rchild;                 

		}

	}

}



void inorder(bintnode* t)

{

	seqstack s;

	s.top=-1;

	while((t!=NULL)||(s.top!=-1))

	{

		while(t)                   

		{

			push(&s,t);         

			t=t->lchild;      

		}

		if(s.top!=-1)

		{

			t=pop(&s);

			cout<<t->data<<"  ";  

			t=t->rchild;           

		}

	}

}



void postorder(bintnode* t)

{

	seqstack s;

	s.top=-1;

	while((t)||(s.top!=-1))

	{

		while(t)

		{

			s.top++;

			s.data[s.top]=t;              

			s.tag[s.top]=0;        

			t=t->lchild;         

		}

		while((s.top>-1)&&(s.tag[s.top]==1))

		{

			t=s.data[s.top];      

			cout<<t->data<<"  "; 

			s.top--;

		}



		if(s.top>-1)

		{

			t=s.data[s.top]; 

			s.tag[s.top]=1;    

			t=t->rchild;   

		}

		else

			t=NULL;

	}

}



int main()

{

	bintnode* tree;

	cout<<"输入根结点：";

	createbintree(tree);



	cout<<"\n前序非递归遍历二叉树:"; 

	preorder(tree);

	cout<<"\n-----------------------------\n";



	cout<<"\n中序非递归遍历二叉树:";

	inorder(tree);

	cout<<"\n----------------------------\n";



	cout<<"\n后序非递归遍历二叉树:";

	postorder(tree);

	cout<<endl;

}