AverageAverage | Topcoder Archive

Problem Statement

Given a int[] numList, for each non-empty subset of numList, compute the average of its elements, then return the average of those averages.

Definition

Class:: AverageAverage
Method:: average
Parameters:: int[]
Returns:: double
Method signature:: double average(int[] numList)
(be sure your method is public)

Notes

The returned value must have an absolute or relative error less than 1e-9.

Constraints

numList will contain between 1 and 8 elements, inclusive.
All elements of numList will be between -1000 and 1000, inclusive.
All elements of numList will be distinct.

Examples

```
{1,2,3}
```
```
Returns: 2.0
```
The non-empty subsets of numList are: {1}, {2}, {3}, {1,2}, {1,3}, {2,3}, and {1,2,3}, whose respective averages are: 1, 2, 3, 1.5, 2, 2.5, and 2. The average of the averages is 2.
```
{42}
```
```
Returns: 42.0
```
There is only one non-empty subset to consider.
```
{3,1,4,15,9}
```
```
Returns: 6.4
```

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