Data Structure Binary Tree: Construct Tree from given Inorder and Preorder traversals

http://www.geeksforgeeks.org/construct-tree-from-given-inorder-and-preorder-traversal/

 1 #include <iostream>
 2 #include <vector>
 3 #include <algorithm>
 4 #include <queue>
 5 #include <stack>
 6 #include <string>
 7 #include <fstream>
 8 using namespace std;
 9 
10 struct node {
11     char data;
12     struct node *left, *right;
13     node() : data(0), left(NULL), right(NULL) { }
14     node(int d) : data(d), left(NULL), right(NULL) { }
15 };
16 
17 
18 void prints(node *root) {
19     if (!root) return;
20     prints(root->left);
21     cout << root->data << " ";
22     prints(root->right);
23 }
24 
25 node *buildtree(char in[], char pre[], int beg, int end) {
26     static int preindex = 0;
27     if (beg > end) return NULL;
28     node *root = new node(pre[preindex++]);
29     int index = beg;
30     for (int i = beg; i <= end; i++) {
31         if (in[i] == root->data) {
32             index = i;
33             break;
34         }
35     }
36     root->left = buildtree(in, pre, beg, index-1);
37     root->right = buildtree(in, pre, index+1, end);
38     return root;
39 }
40 
41 int main() {
42     char in[6] = {'D', 'B', 'E', 'A', 'F', 'C'};
43     char pre[6] = {'A', 'B', 'D', 'E', 'C', 'F'};
44     int len = 6;
45     node *root = buildtree(in, pre, 0, len-1);
46     prints(root);
47     return 0;
48 }