Data Engineer, Analytics

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You are given a binary tree. Write a function to flatten the binary tree into a linked list in-place. The linked list should be in the same order as a pre-order traversal of the binary tree. This means that for each node, the right pointer should point to the next node in the pre-order traversal, and the left pointer should be null. For example, consider the following binary tree: 1 / 2 5 / 3 4 6 After flattening, the tree should look like this: 1 -> 2 -> 3 -> 4 -> 5 -> 6 Each node's right pointer points to the next node in the pre-order traversal, and all left pointers are null. Clarifications: The function should modify the tree in-place. The pre-order traversal should be followed. The left pointers of all nodes should be set to null after flattening. Could you provide an efficient algorithm to accomplish this, and what is the time and space complexity of your solution?

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Let's design a database for a library. Consider the following requirements: Books: The library has a collection of books. Each book has a title, an author (or authors), a publication year, an ISBN, and a genre. A book can have multiple authors. Members: The library has members who can borrow books. Each member has a unique member ID, a name, an address, and a phone number. Borrowing: The library needs to keep track of which books are borrowed by which members and when they are borrowed and returned. A member can borrow multiple books, and a book can be borrowed by multiple members over time. Reservations: Members can reserve books that are currently checked out. The system needs to keep track of reservations and their order. Late Fees: The library charges late fees for overdue books. The system needs to calculate and track these fees. Based on these requirements, design a relational database schema. Include the tables, columns, data types, primary keys, and foreign keys. Provide a brief explanation for each table and the relationships between them. How would you handle the many-to-many relationship between books and authors? How would you handle the many-to-many relationship between members and borrowed books? How would you ensure data integrity, such as preventing a member from borrowing the same book twice at the same time?

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Could you describe a situation where you faced a significant memory leak issue in a C++ application and how you diagnosed and resolved it? Please walk me through the tools and techniques you used, the challenges you encountered, and the ultimate solution you implemented. For example, imagine you're working on a large-scale C++ application for processing high-volume financial transactions. The application is experiencing performance degradation over time, eventually leading to crashes. After initial investigation, you suspect a memory leak. Describe your approach to identifying the source of the leak. Consider discussing the specific tools you might employ, such as memory profilers (e.g., Valgrind, AddressSanitizer), debugging techniques (e.g., heap analysis), and code review strategies. What were some of the initial hypotheses you formed, and how did you validate or refute them? What were the key code areas you focused on based on your initial findings? Furthermore, explain any specific coding practices or patterns that contributed to the leak (e.g., improper use of smart pointers, forgetting to release dynamically allocated memory). How did you correct these issues, and what steps did you take to prevent similar leaks from occurring in the future? Did you implement any automated testing or monitoring to detect memory leaks early on? Finally, reflect on any lessons learned from this experience and how it has shaped your approach to memory management in C++.