The middle of the list
A dashboard shows a campaign’s typical daily spend, and “typical” is whatever lands in the middle once the days are sorted.
- An odd number of readings: the middle one, once sorted.
- An even number: the average of the two middle ones.
- An empty list has no middle: return zero.
median_of(values: list<int>) → float
Where you start
def median_of(values: list[int]) -> float:
Worked examples
| Call | Result |
|---|---|
median_of([3, 1, 2]) | 2.0 |
median_of([1, 2]) | 1.5 |
median_of([5]) | 5.0 |
median_of([5, 1, 4, 2]) | 3.0 |
Hint
Sort a copy, not the caller’s list, then look at the middle pair or single value.
Reference solution in Python
def median_of(values: list[int]) -> float:
xs = sorted(values)
n = len(xs)
if n == 0:
return 0.0
mid = n // 2
return float(xs[mid]) if n % 2 == 1 else (xs[mid - 1] + xs[mid]) / 2