二叉树赋值运算符重载问题C++

class TreeNode {
public:
    int val;
    TreeNode* left;
    TreeNode* right;

    // 构造函数
    TreeNode(int value) : val(value), left(nullptr), right(nullptr) {}
};

class BinaryTree {
private:
    TreeNode* root;

public:
    // 构造函数
    BinaryTree() : root(nullptr) {}

    // 赋值运算符重载
    BinaryTree& operator=(const BinaryTree& other) {
        // 自我赋值检查
        if (this == &other) {
            return *this;
        }

        // 释放当前对象资源
        clear(root);

        // 深拷贝操作
        root = clone(other.root);

        return *this;
    }

private:
    // 释放二叉树资源
    void clear(TreeNode* node) {
        if (node != nullptr) {
            clear(node->left);
            clear(node->right);
            delete node;
        }
    }

    // 深拷贝二叉树
    TreeNode* clone(TreeNode* node) {
        if (node == nullptr) {
            return nullptr;
        }

        TreeNode* newNode = new TreeNode(node->val);
        newNode->left = clone(node->left);
        newNode->right = clone(node->right);

        return newNode;
    }
};