二叉树的建立

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

typedef struct tree       //定义二叉树的结构
{
	char data;
	struct tree *lchild;
	struct tree *rchild;
}BinTree;

/*
**创建二叉树
*/
void CreateTree(BinTree *&pBtree)
{
	char c;
	scanf("%c",&c);
	if(c=='@')        //子树的结束标识符
	{
		pBtree=NULL;
	}
	else
	{
		pBtree=(BinTree *)malloc(sizeof(BinTree));
		if(pBtree==NULL)
		{
			printf("malloc使用失败!\n");
			exit(0);
		}
		pBtree->data=c;
		CreateTree(pBtree->lchild);   //继续递归去建立左右二叉子树
		CreateTree(pBtree->rchild);
	}
}

/*
**先序遍历二叉树
*/

void FirstTraverse(BinTree *&pBtree)
{
	if(pBtree==NULL)
		return;
	printf("%c",pBtree->data);
	FirstTraverse(pBtree->lchild);
	FirstTraverse(pBtree->rchild);
}

/*
**求节点的总数
*/
int sumNode(BinTree *&pBtree)
{
	int sum=0;
	if(pBtree==NULL)
		return 0;
	 sum++;
	 sum+=sumNode(pBtree->lchild);
	 sum+=sumNode(pBtree->rchild);
	 return sum;
}

/*
**销毁二叉树
*/
void DestroyTree(BinTree *&pBtree)
{
	if(pBtree==NULL)
		return;
	DestroyTree(pBtree->lchild);
	DestroyTree(pBtree->rchild);
	free(pBtree);
}

int main()
{
	BinTree *pBtree;
	printf("请输入二叉树的节点:\n");
	CreateTree(pBtree);
	printf("二叉树的先序遍历:\n");
	FirstTraverse(pBtree);
	printf("\n节点总数是:\n");
	printf("%d\n",sumNode(pBtree));
	DestroyTree(pBtree);
	return 0;
}