1 //扩展二叉树 
 2 #include <iostream>
 3 #include <string>
 4 using namespace std;
 5 
 6 string s="ABD..EF..G..C..";
 7 int m=-1;
 8 
 9 typedef struct node{
10     char data;
11     node *lchild,*rchild;
12 }*tree; 
13 
14 
15 void creatTree(tree &bt){
16     if(s[++m]!=‘.‘&&m<s.length()){
17         bt=new node;
18         bt->data=s[m];
19         cout<<bt->data<<" "<<m<<" ";
20         creatTree(bt->lchild);
21         creatTree(bt->rchild);         
22     }
23     else bt=NULL;
24 
25 }
26 //先序遍历 
27 void printxx(tree bt){
28     if(bt){
29         cout<<bt->data<<" ";
30         printxx(bt->lchild);
31         printxx(bt->rchild);
32     }
33 } 
34 
35 //中序遍历 
36 void printzx(tree bt){
37     if(bt){
38         printzx(bt->lchild);
39         cout<<bt->data<<" ";
40         printzx(bt->rchild);
41     }
42 } 
43 
44 //后序遍历 
45 void printhx(tree bt){
46     if(bt){
47         printhx(bt->lchild); 
48         printhx(bt->rchild);
49         cout<<bt->data<<" ";
50     }
51 } 
52 
53 int main(){
54     tree treeHead;
55     creatTree(treeHead);
56     cout<<endl;
57     printxx(treeHead);
58     cout<<endl;
59     printzx(treeHead); 
60     cout<<endl;
61     printhx(treeHead);
62     return 0;
63 }