tasks a-s

Task/Self-referential-sequence/Ada/self-referential-sequence.ada

@@ -0,0 +1,62 @@
+with Ada.Text_IO; use Ada.Text_IO;
+with Ada.Containers.Vectors;
+procedure SelfRef is
+   subtype Seed is Natural range 0 .. 1_000_000;
+   subtype Num is Natural range 0 .. 10;
+   type NumList is array (0 .. 10) of Num;
+   package IO is new Ada.Text_IO.Integer_IO (Natural);
+   package DVect is new Ada.Containers.Vectors (Positive, NumList);
+
+   function Init (innum : Seed) return NumList is
+      list : NumList := (others => 0);
+      number : Seed := innum;  d : Num;
+   begin
+      loop
+         d := Num (number mod 10);
+         list (d) :=  list (d) + 1;
+         number := number / 10; exit when number = 0;
+      end loop; return list;
+   end Init;
+
+   procedure Next (inoutlist : in out NumList) is
+      list : NumList := (others => 0);
+   begin
+      for i in list'Range loop
+         if inoutlist (i) /= 0 then
+            list (i) := list (i) + 1;
+            list (inoutlist (i)) := list (inoutlist (i)) + 1;
+         end if;
+      end loop; inoutlist := list;
+   end Next;
+
+   procedure Show (list : NumList) is begin
+      for i in reverse list'Range loop
+         if list (i) > 0 then
+            IO.Put (list (i), Width => 1); IO.Put (i, Width => 1);
+         end if;
+      end loop; New_Line;
+   end Show;
+
+   function Iterate (theseed : Seed; p : Boolean) return Natural is
+      list : NumList := Init (theseed);
+      vect : DVect.Vector;
+   begin
+      vect.Append (list);
+      loop
+         if p then Show (list); end if;
+         Next (list); exit when vect.Contains (list); vect.Append (list);
+      end loop;
+      return Integer (DVect.Length (vect)) + 1;
+   end Iterate;
+
+   mseed : Seed;
+   len, maxlen : Natural := 0;
+begin
+   for i in Seed'Range loop
+      len := Iterate (i, False);
+      if len > maxlen then mseed := i; maxlen := len; end if;
+   end loop;
+   IO.Put (maxlen, Width => 1); Put_Line (" Iterations:");
+   IO.Put (mseed, Width => 1); New_Line;
+   len := Iterate (mseed, True);
+end SelfRef;