树的创建

代码实现：
 1 void PreCreateTree(Tree& T)
 2 {
 3     int data;
 4     cin >> data;
 5     T = new TREE;
 6     if (data == -1)
 7     {
 8         T = NULL;
 9         return;
10     }
11     T->left = NULL;
12     T->right = NULL;
13     T->data = data;
14     PreCreateTree(T->left);
15     PreCreateTree(T->right);
16 }

1 void PreOrder(Tree& T)
2 {
3     if (T)
4     {
5         cout << T->data << ‘ ‘;
6         PreOrder(T->left);
7         PreOrder(T->right);
8     }
9 }

1 void InOrder(Tree& T)
2 {
3     if (T)
4     {
5         InOrder(T->left);
6         cout << T->data << " ";
7         InOrder(T->right);
8     }
9 }

1 void PostOrder(Tree& T)
2 {
3     if (T)
4     {
5         PostOrder(T->left);
6         PostOrder(T->right);
7         cout << T->data << ‘ ‘;
8     }
9 }