The average so far, after every reading
A quality chart plots not each reading but the average of everything measured up to that point, so a late wobble does not swing the line.
- Every reading is zero or more.
- After each reading, report the mean of every reading so far.
- Drop the fraction — the mean is rounded down to a whole number.
- An empty run of readings gives an empty result.
runningAverage(readings: list<int>) → list<int>
Java needs a compiler and Drill does not host one yet, so this page is the reference rather than an exercise: the problem, worked examples, and the solution in full. To type it out, the same problem runs in Python.
Where you start
List<Integer> runningAverage(List<Integer> readings) {
}Worked examples
| Call | Result |
|---|---|
runningAverage(Main.<Integer>ls(10, 20, 30)) | Main.<Integer>ls(10, 15, 20) |
runningAverage(Main.<Integer>ls(1, 2)) | Main.<Integer>ls(1, 1) |
runningAverage(Main.<Integer>ls(5)) | Main.<Integer>ls(5) |
runningAverage(Main.<Integer>ls()) | Main.<Integer>ls() |
Hint
Carry the running total and divide by how many readings you have seen. Do not re-add the list each step.
Reference solution in Java
List<Integer> runningAverage(List<Integer> readings) {
List<Integer> out = new ArrayList<>();
int total = 0;
for (int i = 0; i < readings.size(); i++) {
total += readings.get(i);
out.add(total / (i + 1));
}
return out;
}