4-10：二叉树镜像

问题：二叉树镜像

输入二叉树，求二叉树的镜像。

void reversetree(TreeNode* tree){    if (tree == NULL)        return;    TreeNode* treeleft = tree->getleft();    TreeNode* treeright = tree->getright();    if (treeleft != NULL)    {        tree->setright(treeleft);        reversetree(treeleft);    }    if (treeright != NULL)    {        tree->setleft(treeright);        reversetree(treeright);    }}