I am trying to solve the following problem with Haskell:
Problem
Define the function sumToLists :: Int -> [[Int]]
that, given a natural number n
, it returns all the lists of positive numbers such that their sum is n
.
I am pretty lost at this problem, maybe using recursion could yield up a solution but I have no clue how to attack this. Any suggestions would be greatly appreciated
sumToLists 0 = [[]]
sumToLists n = [ i: xs | i <- [1..n], xs <- sumToLists (n - i) ]
you need special case for 0
because default will return []
not [[]]
.
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