12th Grade IB Computer Science HL

Solution

Correct: D

A heap is the most suitable data structure for implementing a priority queue because it provides efficient insertion and deletion of elements with the highest (or lowest) priority in O(log n) time. Arrays and linked lists would require O(n) in the worst case for these operations. While a BST could be used, balancing it to maintain efficiency makes heaps a better choice.

Solution

Correct: C

In a balanced binary search tree, the height of the tree is logarithmic with respect to the number of nodes (n). Searching involves traversing down the tree from the root to a leaf, thus the worst-case time complexity is O(log n). O(n) is linear, more typical of searching an unsorted array.

Solution

Correct: D

Procedural abstraction is a feature of procedural programming, where programs are divided into procedures or functions. Object-oriented programming focuses on objects containing data and methods, employing inheritance, polymorphism, and encapsulation for code organization and reusability.

Solution

Correct: B

A virtual function in C++ enables polymorphism by allowing a derived class to override a function in its base class. When a virtual function is called through a base class pointer or reference, the actual function executed is determined at runtime based on the object's type, facilitating dynamic dispatch.

Solution

Correct: B

The Singleton pattern ensures that only one instance of a class is created and provides a global point of access to it. The Factory pattern is for creating objects, the Observer pattern establishes a one-to-many dependency, and the Strategy pattern defines a family of algorithms.

Solution

Correct: B

TCP (Transmission Control Protocol) is a connection-oriented protocol that provides reliable, ordered, and error-checked delivery of data. UDP (User Datagram Protocol) is a connectionless protocol that is faster but unreliable, with no guarantee of delivery or ordering. TCP's reliability features introduce overhead, making UDP faster for applications where some data loss is acceptable.

Solution

Correct: B

Binary search has the best average-case time complexity (O(log n)) for searching a sorted array because it repeatedly divides the search interval in half. Linear search has O(n), while Bubble and Selection Sort are sorting algorithms, not searching algorithms.

Solution

Correct: B

Normalization is the process of organizing data in a database to reduce redundancy and improve data integrity. It involves dividing large tables into smaller tables and defining relationships between them. While it can indirectly improve query performance, its primary goal is data integrity and minimizing redundancy. Encryption and backups are different processes.

Solution

Correct: B

The function `my_function` takes two arguments: `x` and `y`, where `y` has a default value of 2. When the function is called with only one argument (3), it uses the default value of `y`, which is 2. Therefore, the function calculates 3 ** 2 (3 raised to the power of 2), which equals 9.

Solution

Correct: B

Version control systems, like Git, are primarily used for tracking changes to source code, enabling collaboration among developers, and providing a history of modifications. Automated deployment is often integrated with version control, but not its core function. Real-time code execution and automatic code optimization are separate functionalities.

Solution

Correct: B

The 'JOIN' operation in SQL combines rows from two or more tables based on a related column. This allows you to retrieve data from multiple tables in a single query. Filtering is done with `WHERE`, sorting with `ORDER BY`, and insertion with `INSERT`.

Solution

Correct: D

A strong hash function should be difficult to compute (for security reasons) and, most importantly, collision-resistant (meaning it's very unlikely that different inputs will produce the same hash output). A good hash function must efficiently map data while minimizing the likelihood of collisions. If it were easy to compute, it would be vulnerable.

Solution

Correct: A

Abstract classes are designed to prevent direct instantiation. They serve as blueprints for other classes, defining a common interface and potentially providing some shared implementation. The primary goal is to enforce a specific structure and behavior in derived classes. This helps in achieving polymorphism and code reusability. Instantiation prevention is achieved using abstract methods, marked as abstract and only implemented in inheriting non-abstract classes.

Solution

Correct: C

A stack is a linear data structure that operates on the Last-In-First-Out (LIFO) principle. This means the last element added to the stack is the first one removed. Queues follow FIFO, and trees/graphs are examples of hierarchical structures. Double-ended queues (deques) allow additions/removals from both ends.

Solution

Correct: D

Insertion Sort has a worst-case time complexity of O(n^2). While Quick Sort *can* have a worst-case time complexity of O(n^2) , it is only in very specific circumstances. Merge Sort and Heap Sort both have O(n log n) worst-case complexities.

Solution

Correct: B

A firewall acts as a barrier between a trusted network and an untrusted network (e.g., the internet). Its primary purpose is to control network traffic based on pre-defined security rules, blocking unauthorized access and preventing malicious attacks. While encryption can be used in conjunction with a firewall, encryption is a separate task.

Solution

Correct: B

A stack is the best choice for implementing undo/redo functionality. Each action is pushed onto the stack. To undo, the top action is popped from the stack and reversed. To redo, the undone action is pushed back onto the stack. This LIFO (Last-In-First-Out) behavior perfectly matches the undo/redo process.

Solution

Correct: B

The 'WHERE' clause in a SQL query is used to filter the rows returned by the query, based on a specified condition. This allows you to retrieve only the data that meets your criteria. Sorting is done with `ORDER BY`, joining with `JOIN`, and grouping with `GROUP BY`.

Solution

Correct: A

Dependency Injection (DI) is a design pattern that aims to reduce coupling between classes by providing dependencies to a class from an external source, rather than having the class create its own dependencies. This promotes modularity, testability, and reusability. It does *not* increase coupling, create singletons, or enforce strict inheritance.