关于C++二分搜索树的中序遍历和先序遍历

#include<iostream>
using namespace std;
struct Node
{
Node *lc;
Node *rc;
int data;
Node(int a)
{
data = a;
lc = NULL;
rc = NULL;
}
};
void built(Node* &root , int a)
{
if(root == NULL)
{
root = new Node(a);
root->lc = NULL;
root->rc = NULL;
}
else
{
if(a > root->data)
{
return built(root->rc , a);
}
else
{
return built(root->lc , a);
}
}
}
void inorder(Node* root)
{
if(root != NULL)//即为先对左子树进行遍历，到底后输入在逐步对右子树进行遍历，也可以验证二分搜索树是否有序
{
inorder(root->lc);
cout << root->data << " ";
inorder(root->rc);
}
}
void preorder(Node* root)
{
if(root != NULL)//先输出根值在对左子树进行遍历，最后对右子树进行遍历
{
cout << root->data << " ";
preorder(root->lc);
preorder(root->rc);
}
}
int main()
{
int n;
cout << "请输入元素数目：";
while(cin >> n && n != 0)
{
Node *root = NULL;
cout << "请输入元素：";
for(int i = 0 ; i < n ; i ++)
{
int a;
cin >> a;
built(root,a);
}
cout << "中序遍历结果为：";
inorder(root);
cout << endl;
cout << "前序遍历结果为：";
preorder(root);
cout << endl << "请输入下一次元素数目，结束请输入'0':";
}
cout << endl;
return 0;
}