二叉树的创建及其遍历

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

struct Bintree
{
	char info;
	struct Bintree *lchild,*rchild;
};
typedef struct Bintree *BinTreeNode;

typedef struct Node *PNode;//栈的存储结构
struct Node
{
	BinTreeNode c;
	PNode link;
};

struct LinkStack//链接栈类型定义
{
  PNode  top;//指向栈顶元素
};
typedef struct LinkStack *PLStack;//链接栈类型定的指针类型

PLStack Cstack()//创建空栈
{
	PLStack plstack;
    plstack=(PLStack)malloc(sizeof(PLStack));
    if(plstack!=NULL) plstack->top=NULL;
    else printf("out of space") ;
    return plstack;
}

int isemptystack(PLStack plstack) //判断是否是空栈
{
	return (plstack->top==NULL);
}

void push(PLStack plstack, BinTreeNode x) //进栈运算
	{
		PNode  p;
    	p=(PNode)malloc(sizeof(struct Node));
    	if(p==NULL)
    	 printf("out of space");
    	else
		{
			p->c=x;
    		p->link=plstack->top;
  			plstack->top=p;

  		}
	}

void pop (PLStack plstack)//出栈运算
{

    	PNode p;
    	if(isemptystack(plstack))
  		 //判断栈是否为空，空栈不进行任何操作，
   		//否则出栈运算，修改指针
   		  printf("Empty stack pop.\n");
    else
    {
  		p=plstack->top;
  		printf("%c",p->c->info);
   		plstack->top=plstack->top->link;
  		free(p);
    }
}

BinTreeNode top(PLStack plstack)//取栈顶元素
{
	if(plstack->top==NULL)//判断栈顶是否空栈
    printf("Stack is Empty");
    else
	{
		return (plstack->top->c);
	}
}

BinTreeNode  CBintree()
{
	char c;
	BinTreeNode p;
	scanf("%c",&c);
	getchar();
	if(c!='#')
		{
			p=(BinTreeNode)malloc(sizeof(BinTreeNode));
			p->info=c;
			p->lchild=CBintree();
			p->rchild=CBintree();
		}
	else
		p=NULL;
		return p;
}

void npreOreder(BinTreeNode t)
//先根次序次序周游
{
	PLStack s;
	BinTreeNode c;
	if(t==NULL)  return;
	s=Cstack();
	push(s,t);
	while(!isemptystack(s))
	{
		c=top(s);pop(s);
		if(c!=NULL)
		{

			if(c->rchild!=NULL) push(s,c->rchild);
			if(c->lchild!=NULL) push(s,c->lchild);
		 }
	}
}

void ninOder(BinTreeNode t)
//中根次序周游
{
	PLStack s=Cstack();
	BinTreeNode c=t;
	if(c==NULL)	return;
	do{
		while(c!=NULL){push(s,c);c=c->lchild;	}
		c=top(s);pop(s);c=c->rchild;
	}while(c!=NULL||!isemptystack(s));
 }

void npostOrder(BinTreeNode t)
{
	PLStack s=Cstack();
	BinTreeNode p=t;
	while(p!=NULL||!isemptystack(s))
	{
		while(p!=NULL){
		push(s,p) ;
		p=p->lchild?p->lchild:p->rchild;
		}
		p=top(s);	pop(s);

		if(!isemptystack(s)&&top(s)->lchild==p)
			p=top(s)->rchild;
		else	p=NULL;
	}

}
int dfs_Tree(BinTreeNode t,int a){
	if(t==NULL){
	    return a;
	}
	if(t->lchild!=NULL)return dfs_Tree(t->lchild,a+1);
	if(t->rchild!=NULL)return dfs_Tree(t->rchild,a+1);
	return a;

}
int main()
{
	BinTreeNode root=(BinTreeNode)malloc(sizeof(BinTreeNode));
	root=CBintree();
	printf("先根");		npreOreder(root);
	printf("中根");		ninOder(root);
	printf("后根");		npostOrder(root);

	printf("\n%d",dfs_Tree(root,1));
	return 0;
}