Mean of array using recursion

Given an array arr[] of integers, calculate the mean (average) using recursion.

Note: The mean of an array is the sum of its elements divided by the number of elements in the array.

Examples:

Input: arr[] = [1, 2, 3, 4, 5]
Output: 3
Explanation: The sum of elements (15) divided by the number of elements (5) gives the mean: 3

Input: arr[] = [1, 2, 3]
Output: 2
Explanation: The sum of elements (6) divided by the number of elements (3) gives the mean: 2

[Approach] - Using Recursion - O(n) Time and O(n) Space

The idea is to compute the mean recursively by building it from smaller prefixes of the array.
Let mean(arr, n) represent the mean of the first n elements. We first calculate the mean of the first n−1 elements recursively. Since the mean of n−1 elements equals their sum divided by (n−1), multiplying it by (n−1) gives their total sum. We then add the nth element arr[n−1] to this sum and divide the result by n to obtain the mean of the first n elements.

The recursive formula for calculating the mean of an array is:

3