Question

I would like to compute the average of three numbers, like:

d = int(round((a + b + c) / 3.0))

Where a, b, c, d are integers.

Is it possible to get the same result using just integers?

I’m interested in this because of performance reasons, I assume doing the math using integers should be faster than using floats.

The example above converts the integers to floats, calculates the result, rounds it and converts back to integer. Is it possible to avoid the int <-> float conversions?

Answer 1

Given the requirements for 1, 1, 2 -> 1; 1, 2, 2 -> 2 then this can be done using integer division.

Using // for the integer division and n for number of elements.

average = ( a+ b + c + .... + n//2 ) // n

ie sum up all the values and then add a number to deal with rounding.

As noted in @Henrik’s answer this assumes that all numbers are positive.