Data Structure Binary Tree: Iterative Postorder Traversal

http://www.geeksforgeeks.org/iterative-postorder-traversal-using-stack/

 #include <iostream>
 #include <vector>
 #include <algorithm>
 #include <queue>
 #include <stack>
 #include <string>
 #include <fstream>
 #include <map>
 using namespace std;

 struct node {
     int data;
     struct node *left, *right;
     node() : data(), left(NULL), right(NULL) { }
     node(int d) : data(d), left(NULL), right(NULL) { }
 };

 void prints(node *root) {
     if (!root) return;
     stack<node*> S;
     do {
         while (root) {
             if (root->right) S.push(root->right);
             S.push(root);
             root = root->left;
         }
         root = S.top();
         S.pop();
         if (root->right && !S.empty() && root->right == S.top()) {
             S.pop();
             S.push(root);
             root = root->right;
         }
         else {
             cout << root->data << " ";
             root = NULL;
         }
     } while (!S.empty());
 }

 int main() {
     node *root = new node();
     root->left = new node();
     root->right = new node();
     root->left->left = new node();
     root->left->right = new node();
     root->right->left = new node();
     root->right->right = new node();
     prints(root);
     return ;
 }