有一个排序二叉树，数据类型是int型，如何找出中间大的元素。

void tree2Dll(TNode* root, TNode*& tail) {if (!root) {return;}if (root->left) {tree2Dll(root->left, tail);}TNode* tmp = root;tmp->left = tail;if (tail) {tail->right = tmp;}tail = tmp;if (root->right) {tree2Dll(root->right, tail);}}int findMedian(TNode* tail) {if (!tail) {return INT_MAX;}TNode* fast = tail;TNode* slow = tail;while (fast && slow) {if (!(fast->left)) {return slow->data;} else if (fast->left && !(fast->left->left)) {return (slow->data + slow->left->data) >> 1;} else {slow = slow->left;fast = fast->left->left;}}}