建立二叉树

void createBiTree(TreeNode* &T) //&的意思是传进来节点指针的引用，括号内等价于 BiTreeNode* &T,目的是让传递进来的指针发生改变
{
	char c;
	cout << "input treeNode:";
	cin >> c;
	if ('#' == c)             //当遇到#时，令树的根节点为NULL，从而结束该分支的递归
		T = NULL;
	else
	{
		T = new TreeNode(0);
		T->val = c - '0';
		createBiTree(T->left);
		createBiTree(T->right);
	}
}
TreeNode* CreateBiTree()
{
	char a;
	TreeNode* T;
	cin >> a;
	if (a == '#')
		T = NULL;
	else
	{
		T = (TreeNode*)malloc(sizeof(TreeNode));
		T->val = a - '0';
		T->left = CreateBiTree();
		T->right = CreateBiTree();
	}
	return T;//返回根节点
}