Data Structure Binary Tree: Largest Independent Set Problem

http://www.geeksforgeeks.org/largest-independent-set-problem/

 #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) { }
 };

 int LISS(node *root) {
     if (!root) return ;
     int sum = ;
     if (root->left) sum += LISS(root->left->left) + LISS(root->left->right);
     if (root->right) sum += LISS(root->right->left) + LISS(root->right->right);
     return max(sum, LISS(root->left) + LISS(root->right));
 }

 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->left->right->left = new node();
     root->left->right->right = new node();
     root->right->right = new node();
     cout << LISS(root);
     return ;
 }