> > > http://stackoverflow.com/questions/8940470/algorithm-for-finding-numerical-permutation-given-lexicographic-index > > How would you rewrite this into Haskell? The code snippet is in Scala. > > /** > example: index:=15, list:=(1, 2, 3, 4) > */ > def permutationIndex (index: Int, list: List [Int]) : List [Int] = > if (list.isEmpty) list else { > val len = list.size // len = 4 > val max = fac (len) // max = 24 > val divisor = max / len // divisor = 6 > val i = index / divisor // i = 2 > val el = list (i) > el :: permutationIndex (index - divisor * i, list.filter (_ != el)) } > > >
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