System Design and Architecture 1 — Questions and Answers

Question 1: You are given an array [2, 7, 11, 15] and a target 9. Which pair of indices will sum up to the target?

[0, 2]
[0, 1] (Correct answer)
[1, 2]
[2, 3]

Correct answer: [0, 1]

To find the pair of indices that sum to the target, we examine the elements of the array [2, 7, 11, 15]. The element at index 0 is 2, and the element at index 1 is 7. Adding these two values (2 + 7) equals 9, which matches the target. Therefore, the indices [0, 1] correspond to the elements that sum to the target.

Question 2: Which of the following sorting algorithms has the best average-case time complexity?

Bubble Sort
Quick Sort
Merge Sort (Correct answer)
Selection Sort

Correct answer: Merge Sort

While Quick Sort often performs very well in practice with an average-case time complexity of O(n log n), its worst-case complexity is O(n^2). Merge Sort, on the other hand, consistently maintains an O(n log n) time complexity in its best, average, and worst-case scenarios. This makes Merge Sort a more reliably efficient choice for its average-case performance compared to the other options listed.

Question 3: Which type of SQL join returns all records from the left table and matching records from the right table?

INNER JOIN
LEFT JOIN (Correct answer)
RIGHT JOIN
FULL OUTER JOIN

Correct answer: LEFT JOIN

A `LEFT JOIN` (also known as `LEFT OUTER JOIN`) returns all rows from the "left" table (the first table mentioned in the `FROM` clause) and the matching rows from the "right" table. If there is no match in the right table, `NULL` values are returned for the columns from the right table. This ensures that no data from the left table is lost.

Question 4: What is the time complexity of traversing a singly linked list with n elements?

O(1)
O(log n)
O(n) (Correct answer)
O(n²)

Correct answer: O(n)

To traverse a singly linked list, you must visit each node sequentially from the head to the tail. In a list with 'n' elements, this requires 'n' steps, as you can only move forward one node at a time. Therefore, the time complexity for traversing the entire list is directly proportional to the number of elements, which is O(n).

Question 5: Consider the following Python function: def add_numbers(a, b): return a + b print(add_numbers(2))

TypeError (Correct answer)
ValueError
SyntaxError
IndexError

Correct answer: TypeError

The `add_numbers` function is defined to accept two arguments, `a` and `b`. However, when `print(add_numbers(2))` is called, only one argument is provided. Python will raise a `TypeError` because the function call is missing the required second positional argument `b`.

System Design and Architecture 1

You are given an array [2, 7, 11, 15] and a target 9.
Which pair of indices will sum up to the target?