The overflow thing would be about computing the median of some sub-range of a sorted array. It is an often-quizzed thing that comes up as an edge case in binary search of a large array, but could apply to anything where you need to select the middle element of a sub-range of an array and the sum of the start/end indices could overflow.

I think the lore is that it was a bug in Java?'s binary search lib decades ago?

> That's average or mean. Median is the middle value.

The median of an even number of values is typically defined to be the mean of the two middle-most values.

There's also an interesting relationship to variance when you only have mean and median