其中findMax和findMin分别为寻找树的最大值和最小值的函数。

struct TreeNode {    int val;    TreeNode* left;    TreeNode* right;    TreeNode(int x): val(x), left(nullptr), right(nullptr) {}};TreeNode* deleteNode(TreeNode* root, int key) {    if (!root) return nullptr;    if (key < root->val) {        root->left = deleteNode(root->left, key);    }    else if (key > root->val) {        root->right = deleteNode(root->right, key);    }    else {        if (!root->left) return root->right;        if (!root->right) return root->left;        TreeNode* temp = ____________; // 在此处填写代码        root->val = temp->val;        root->right = deleteNode(root->right, temp->val);    }    return root;}