Sync

Task/Topswops/Haskell/topswops-2.hs

@@ -2,11 +2,10 @@ import Data.List
 import Control.Arrow
 import Control.Monad
 
-derangements [1] = [[1]]
-derangements xs = filter (and . zipWith (/=) [1..] ). permutations $ xs
+derangements = filter (and . zipWith (/=) [1..] ). permutations
 topswop = ((uncurry (++). first reverse).). splitAt
 topswopIter = takeWhile((/=1).head). iterate (topswop =<< head)
 swops =  map (length. topswopIter). derangements
 
 topSwops :: [Int] -> [(Int, Int)]
-topSwops = zip [1..]. map (maximum. swops). drop 1. inits
+topSwops = zip [1..]. map (maximum. (0:). swops). tail. inits

Task/Topswops/Haskell/topswops-3.hs

@@ -0,0 +1,21 @@
+procedure main()
+    every n := 1 to 10 do {
+        ts := 0
+        every (ts := 0) <:= swop(permute([: 1 to n :]))
+        write(right(n, 3),": ",right(ts,4))
+        }
+end
+
+procedure swop(A)
+    count := 0
+    while A[1] ~= 1 do {
+        A := reverse(A[1+:A[1]]) ||| A[(A[1]+1):0]
+        count +:= 1
+        }
+    return count
+end
+
+procedure permute(A)
+    if *A <= 1 then return A
+    suspend [(A[1]<->A[i := 1 to *A])] ||| permute(A[2:0])
+end