Implement Safe Average Function
Company: Waymo
Role: Data Scientist
Category: Coding & Algorithms
Difficulty: medium
Interview Round: Take-home Project
Write a Python function `average(values)` that returns the arithmetic mean of a list of numbers.
Requirements:
- If `values` is empty, return `0`.
- The input is a flat list of numeric values such as integers or floats.
- Do not mutate the input list.
Examples:
- `average([1, 2, 3])` returns `2.0`
- `average([-1, 1])` returns `0.0`
- `average([])` returns `0`
Quick Answer: This question evaluates proficiency with basic programming fundamentals including numeric computation, handling edge cases such as empty inputs, input immutability, and data type consistency.
Write a function `solution(values)` that returns the arithmetic mean of a flat list of numeric values. The arithmetic mean is the sum of all values divided by the number of values. If the list is empty, return `0`. The function must not mutate the input list.
Constraints
- 0 <= len(values) <= 100000
- Each element of values is an integer or float
- Values are finite numeric values
- The input list must not be mutated
Examples
Input: ([1, 2, 3],)
Expected Output: 2.0
Explanation: The sum is 6 and there are 3 values, so the average is 6 / 3 = 2.0.
Input: ([-1, 1],)
Expected Output: 0.0
Explanation: The sum is 0 and there are 2 values, so the average is 0 / 2 = 0.0.
Hints
- Handle the empty list case before dividing to avoid division by zero.
- You only need the total sum and the number of elements.