Initial data commit

Task/Topswops/Factor/topswops.factor

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+USING: formatting kernel math math.combinatorics math.order
+math.ranges sequences ;
+FROM: sequences.private => exchange-unsafe ;
+IN: rosetta-code.topswops
+
+! Reverse a subsequence in-place from 0 to n.
+: head-reverse! ( seq n -- seq' )
+    dupd [ 2/ ] [ ] bi rot
+    [ [ over - 1 - ] dip exchange-unsafe ] 2curry each-integer ;
+
+! Reverse the elements in seq according to the first element.
+: swop ( seq -- seq' ) dup first head-reverse! ;
+
+! Determine the number of swops until 1 is the head.
+: #swops ( seq -- n )
+    0 swap [ dup first 1 = ] [ [ 1 + ] [ swop ] bi* ] until
+    drop ;
+
+! Determine the maximum number of swops for a given length.
+: topswops ( n -- max )
+    [1,b] <permutations> [ #swops ] [ max ] map-reduce ;
+
+: main ( -- )
+    10 [1,b] [ dup topswops "%2d: %2d\n" printf ] each ;
+
+MAIN: main