【数据结构与算法面试题】二叉树镜像

void tree_swap(BSTreeNode *root){
    BSTreeNode *p_tmp = root->m_pLeft;
    root->m_pLeft = root->m_pRight;
    root->m_pRight = p_tmp;
}

void tree_mirror(BSTreeNode *root){
    if (NULL == root ||
        (NULL == root->m_pLeft && NULL == root->m_pRight)){
        return;
    }

    tree_swap(root);
    tree_swap(root->m_pLeft);
    tree_swap(root->m_pRight);
}

void tree_mirror_loop(BSTreeNode *root){
    if (NULL == root ||
        (NULL == root->m_pLeft && NULL == root->m_pRight)){
        return;
    }

    BSTreeNode *p = root;
    queue<BSTreeNode *> q_tree;
    q_tree.push(p);
    while (! q_tree.empty()){
        BSTreeNode *q = q_tree.front();
        q_tree.pop();
        if (NULL != q->m_pLeft || NULL != q->m_pRight){
            tree_swap(q);
        }
        if (NULL != q->m_pLeft) q_tree.push(q->m_pLeft);
        if (NULL != q->m_pRight) q_tree.push(q->m_pRight);
    }
}