Google Cloud Professional Cloud Developer — Question 75

You are parsing a log file that contains three columns: a timestamp, an account number (a string), and a transaction amount (a number). You want to calculate the sum of all transaction amounts for each unique account number efficiently.
Which data structure should you use?

Answer options

• A. A linked list
• B. A hash table
• C. A two-dimensional array
• D. A comma-delimited string

Correct answer: B

Explanation

A hash table is ideal for this scenario because it allows for fast lookups and updates, making it easy to aggregate transaction amounts by unique account numbers. In contrast, a linked list would be inefficient for this purpose as it does not provide quick access to elements, a two-dimensional array lacks the flexibility for dynamic keys, and a comma-delimited string does not structure data in a way that supports efficient calculations.