[Python-ideas] Haskell envy

Steven D'Aprano steve at pearwood.info
Mon Apr 23 19:24:54 CEST 2012

Nestor wrote:
> The other day a colleague of mine submitted this challenge taken from
> some website to us coworkers:
> Have the function ArrayAddition(arr) take the array of numbers stored
> in arr and print true if any combination of numbers in the array can
> be added up to equal the largest number in the array, otherwise print
> false. For example: if arr contains [4, 6, 23, 10, 1, 3] the output
> should print true because 4 + 6 + 10 + 3 = 23.  The array will not be
> empty, will not contain all the same elements, and may contain
> negative numbers.

By the way, your solution is wrong. Consider this sample data:

-2, -5, 0, -1, -3

In this case, the Haskell solution should correctly print true, while yours 
will print false, because you skip the empty subset. The empty sum equals the 
maximum value of the set, 0.

The ease at which people can get this wrong is an argument in favour of a 
standard solution.


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