CareerCup-4.7

You have two very large binary trees: T1, with millions of nodes, and T2, with hundreds of nodes Create an algorithm to decide if T2 is a subtree of T1 

#include <iostream>  using namespace std;  typedef int Data;    struct Node  {      Node(Data d):data(d){left = right = NULL;};      Data data;      Node* left;      Node* right;    Node* parent; };  class Tree  {  public:      Tree():root(NULL){};      Node* root;    bool contains(Tree dst)    {        return subTree(root, dst.root);     }; private:        bool matchTree(Node* a, Node* b)    {        if(a == NULL && b == NULL)            return true;        if(a != NULL && b != NULL && a->data == b->data)            return matchTree(a->left, b->left) && matchTree(a->right, b->right);        return false;    };         bool subTree(Node* a, Node* b)    {        if(b == NULL)            return true;        if(a == NULL)            return false;        if(a->data == b->data)        {            return matchTree(a, b);        } else {            return subTree(a->left, b) || subTree(a->right, b);        }            };};int main()  {      Tree tree;    tree.root = new Node(5);    tree.root->left = new Node(1);    tree.root->right = new Node(7);    tree.root->left->right = new Node(4);    tree.root->left->right->left = new Node(3);    Tree tree2;    tree2.root = new Node(4);    tree2.root->left = new Node(3);    cout<<boolalpha<<tree.contains(tree2);    system("pause");  };