#include<stdio.h>
#include<malloc.h>
char ch[]={'a','b','c',' ',' ','d',' ',' ','e','f',' ',' ','g',' ',' '}; 
int i=0;
typedef struct bitnode
{
	char data;
	struct bitnode *lchild,*rchild;
}bitnode,*bitree;

int dcreatebitree(bitree &t)
{
	if(ch[i++]==' ')
		t=NULL;
	else
	{
		if(!(t=(bitnode*)malloc(sizeof(bitnode))))
		   printf("溢出！\n");
        t->data=ch[i-1];
		printf("%c ",t->data);
		dcreatebitree(t->lchild);
		dcreatebitree(t->rchild);
	}
	return 1;
}

int preordertraverse(bitree t)
{
	if (t) 
	{
		  printf("%c ",t->data);
          preordertraverse(t->lchild);
          preordertraverse(t->rchild);
    }  
    return 1;
}

int midordertraverse(bitree t)
{
	if (t) 
	{
          midordertraverse(t->lchild);
		  printf("%c ",t->data);
          midordertraverse(t->rchild);
    }  
    return 1;
}

int backordertraverse(bitree t)
{
	if (t) 
	{
          backordertraverse(t->lchild);
          backordertraverse(t->rchild);
		  printf("%c ",t->data);
    }  
    return 1;
}

void main()
{
	bitree b;
	dcreatebitree(b);
	printf("\n");
	printf("二叉樹建立成功！\n");
	int i;
	int t=1;
	while(t)
	{
		printf("請輸入您要執行的操作：1為先先序遍厲，2為中序遍厲，3為后序遍厲,0為退出\n");
	    scanf("%d",&i);
		if(i==1)
		{
        	printf("先序遍厲此二叉樹：\n");
            preordertraverse(b);
	        printf("\n");
		}
	    else if(i==2)
		{
	        printf("中序遍厲此二叉樹：\n");
            midordertraverse(b);
	        printf("\n");
		}
	    else if(i==3)
		{
	        printf("后序遍厲此二叉樹：\n");
	        backordertraverse(b);
         	printf("\n");
		}
		else if(i==0)break;
	}

}