12. Calculate the Average of Array Elements
Given an array of numbers, calculate the average of all elements.
How It Works & Algorithmic Design
The average is calculated as sum / count:
- Initialize a
sumvariable to0. - Traverse every element and add it to
sum. - After traversal, divide
sumby the number of elements. - Handle an empty array separately because division by zero is invalid.
Why This Approach Works Best
The array only needs to be traversed once. The algorithm requires $O(n)$ time and $O(1)$ auxiliary space.
Example Walkthrough
Input:
[10, 20, 30, 40]Four numerical values are provided.
Sum:
10 + 20 + 30 + 40 = 100All values are accumulated.
Output:
25Average = 100 / 4 = 25.
Answer: Calculate array average
function average(arr) {
if (arr.length === 0) return null;
let sum = 0;
for (const value of arr) {
sum += value;
}
return sum / arr.length;
}💡 First calculate the total sum and then divide it by the number of elements.
Key Takeaways
- Average is calculated as total sum divided by number of elements.
- Always handle an empty array before dividing.
- The algorithm runs in O(n) time and O(1) space.