创建一棵二叉树并输出节点

 1 #include<iostream>
 2 using namespace std;
 3 
 4 typedef struct BiTreeNode{
 5     int data;
 6     struct BiTreeNode *left;
 7     struct BiTreeNode *right;
 8 }BiTreeNode; 
 9 
10 //创建二叉树，使用前序创建二叉树，遇到-1表示节点为空
11 BiTreeNode* createTree()
12 {
13     int item;
14     BiTreeNode *t ;
15     cin>>item;
16     
17     if(item != -1)
18     {
19         BiTreeNode *pTmpNode = new BiTreeNode();
20         
21         t = pTmpNode;
22         pTmpNode->data = item;
23         
24         t->left = createTree();
25         t->right = createTree();
26         return t;
27     } 
28     else
29     {
30         t = NULL;
31         return t;
32     }
33 }
34 
35 void pre_order(BiTreeNode *r)
36 {
37     BiTreeNode *pTmpNode = r;
38     
39     if(pTmpNode != NULL)
40     {
41         cout<<pTmpNode->data<<" ";
42         pre_order(pTmpNode->left);
43         pre_order(pTmpNode->right);
44     }
45 }
46 
47 int main(){
48     BiTreeNode *node;
49     node = createTree();
50     pre_order(node);
51     return 0;
52 }