求二叉树结点的个数

#include
#include

typedef char ElemType;
typedef struct BTNode{
	ElemType data;
	struct BTNode *lchild;
	struct BTNode *rchild;
}BTNode,*BiTree;

void createBiTree(BTNode *&B)
{
	ElemType ch;
	scanf("%c",&ch);
	if(ch== ' ') B=NULL;
	else
	{
		B = (BTNode*)malloc(sizeof(BTNode));
		B->data = ch;
		createBiTree(B->lchild);
		createBiTree(B->rchild);
	}
}

int countNode(BiTree B)
{
	if(!B)
		return 0;
	else
		return 1 + countNode(B->lchild) + countNode(B->rchild);
}

void printPreOrder(BiTree B)
{
	if(B)
	{
		printf("%c ",B->data);
		printPreOrder(B->lchild);
		printPreOrder(B->rchild);
	}
}

void main()
{
	BiTree B;
	createBiTree(B);
	printf("先序遍历：");
	printPreOrder(B);
	printf("n");
	printf("结点个数：%dn",countNode(B));
}

按先序遍历来输入二叉树结点，若孩子结点为空，则输入空格。