John D. Ramsdell wrote:
Straight forward permation algorithm.permutations :: Int -> [[Int]] permutations n | n <= 0 = [] | n == 1 = [[0]]
Btw. I think that case is redundant.
| otherwise = concatMap (insertAtAllPos (n - 1)) (permutations (n - 1)) where insertAtAllPos x [] = [[x]] insertAtAllPos x (y : l) = (x : y : l) : map (y :) (insertAtAllPos x l)
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