Data Structure Binary Tree: Print ancestors of a given binary tree node without recursion

http://www.geeksforgeeks.org/print-ancestors-of-a-given-binary-tree-node-without-recursion/
 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 printancestor(node *root, int key) {
19     if (!root) return;
20     stack<node*> S;
21     while (1) {
22         while (root && root->data != key) {
23             S.push(root);
24             root = root->left;
25         }
26         if (root && root->data == key) break;
27         if (S.top()->right == NULL) {
28             root = S.top();
29             S.pop();
30             while (!S.empty() && S.top()->right == root) {
31                 root = S.top();
32                 S.pop();
33             }
34         }
35         root = S.empty()? NULL : S.top()->right;
36     }
37     while (!S.empty()) {
38         cout << S.top()->data << " ";
39         S.pop();
40     }
41 }
42 
43 int main() {
44     node *root = new node(1);
45     root->left = new node(2);
46     root->right = new node(3);
47     root->left->left = new node(4);
48     root->left->right = new node(5);
49     root->right->left = new node(6);
50     root->right->right = new node(7);
51     root->left->left->left = new node(8);
52     root->left->right->right = new node(9);
53     root->right->right->left = new node(10);
54     for (int i = 1; i < 11; i++) {
55         printancestor(root, i);
56         cout << endl;
57     }
58     return 0;
59 }