Data commit

Task/Topswops/Ada/topswops.ada

@@ -0,0 +1,39 @@
+with Ada.Integer_Text_IO, Generic_Perm;
+
+procedure Topswaps is
+
+   function Topswaps(Size: Positive) return Natural is
+      package Perms is new Generic_Perm(Size);
+      P: Perms.Permutation;
+      Done: Boolean;
+      Max: Natural;
+
+      function Swapper_Calls(P: Perms.Permutation) return Natural is
+	 Q: Perms.Permutation := P;
+	 I: Perms.Element := P(1);
+      begin
+	 if I = 1 then
+	    return 0;
+	 else
+	    for Idx in 1 .. I loop
+	       Q(Idx) := P(I-Idx+1);
+	    end loop;
+	    return 1 + Swapper_Calls(Q);
+	 end if;
+      end Swapper_Calls;
+
+   begin
+      Perms.Set_To_First(P, Done);
+      Max:= Swapper_Calls(P);
+      while not Done loop
+	 Perms.Go_To_Next(P, Done);
+	 Max := natural'Max(Max, Swapper_Calls(P));
+      end loop;
+      return Max;
+   end Topswaps;
+
+begin
+   for I in 1 .. 10 loop
+      Ada.Integer_Text_IO.Put(Item => Topswaps(I), Width => 3);
+   end loop;
+end Topswaps;