Binary tree

[nguyenhanh.52889]

#include <iostream>#include <queue> //// Use Queue is available in C ++ using namespace std; // create one node of the treestruct CTreeNode {    int Key;    CTreeNode* Left;    CTreeNode* Right;     CTreeNode(int _key) : Key(_key),        Left(0), Right(0) {}}; class Tree {public:    Tree();    ~Tree();    CTreeNode* Root() { return root; };    void addNode(int key);    void levelOrder();private:    void addNode(int key, CTreeNode* leaf);    void freeNode(CTreeNode* leaf);    CTreeNode* root;}; Tree::Tree() {    root = 0;} Tree::~Tree() {    freeNode(root);}   void Tree::freeNode(CTreeNode* leaf){    if (leaf != 0)    {        freeNode(leaf->Left);        freeNode(leaf->Right);        delete leaf;    }} void Tree::addNode(int key) {    if (root == 0) {        CTreeNode* n = new CTreeNode(key);        root = n;    }    else {        addNode(key, root);    }} void Tree::addNode(int key, CTreeNode* leaf){    if (key <= leaf->Key) {        if (leaf->Left != 0)            addNode(key, leaf->Left);        else        {            CTreeNode* n = new CTreeNode(key);            leaf->Left = n;        }    }    else {        if (leaf->Right != 0)            addNode(key, leaf->Right);        else {            CTreeNode* n = new CTreeNode(key);            leaf->Right = n;        }    }}   // Traversing the tree in width void Tree::levelOrder() {     queue<CTreeNode*> q;     q.push(root);     while (!q.empty())    {        CTreeNode* p = q.front(); // take the surrender value        cout << p->Key << " ";  // print key         if (p->Left != 0)            q.push(p->Left);         if (p->Right != 0)            q.push(p->Right);         q.pop();    }} int main() {    Tree* tree = new Tree();     int N;    cin >> N;    int K;     for (int i = 0; i < N; i++)    {        cin >> K;        tree->addNode(K);    }    tree->levelOrder();         //system("pause");    return 0;}