Data Structure Binary Tree: Morris traversal for Preorder

http://www.geeksforgeeks.org/morris-traversal-for-preorder/
 1 #include <iostream>
 2 #include <vector>
 3 #include <algorithm>
 4 #include <queue>
 5 #include <stack>
 6 #include <string>
 7 #include <fstream>
 8 #include <map>
 9 using namespace std;
10 
11 struct node {
12     int data;
13     struct node *left, *right;
14     node() : data(0), left(NULL), right(NULL) { }
15     node(int d) : data(d), left(NULL), right(NULL) { }
16 };
17 
18 void prints(node *root) {
19     while (root) {
20         if (root->left == NULL) {
21             cout << root->data << " ";
22             root = root->right;
23         }
24         else {
25             node* cur = root->left;
26             while (cur->right && cur->right != root) cur = cur->right;
27             if (cur->right == NULL) {
28                 cout << root->data << " ";
29                 cur->right = root;
30                 root = root->left;
31             }
32             else {
33                 cur->right = NULL;
34                 root = root->right;
35             }
36         }
37     }
38 }
39 
40 int main() {
41     node *root = new node(1);
42     root->left = new node(2);
43     root->right = new node(3);
44     root->left->left = new node(4);
45     root->left->right = new node(5);
46     root->right->left = new node(6);
47     root->right->right = new node(7);
48     root->left->left->left = new node(8);
49     root->left->left->right = new node(9);
50     root->left->right->left = new node(10);
51     root->left->right->right = new node(11);
52     prints(root);
53     return 0;
54 }