Method max

publication/code/chapter08/bst.rs:215–224

(&self)

    }

    fn max(&self) -> (Option<&T>, Option<&U>) {
        // 最大值一定在最右侧
        match &self.right {
            Some(node) => node.max(),
            None => match &self.key {
                Some(key) => (Some(&key), self.val.as_ref()),
                None => (None, None),
            },
        }
    }

    // 获取左右子节点
    fn get_left(&self) -> Link<T,U> {