Data commit

Task/Smith-numbers/Ada/smith-numbers.ada

@@ -0,0 +1,27 @@
+with Ada.Text_IO;
+
+procedure smith is
+  type Vector is array (natural range <>) of Positive;
+  empty_vector : constant Vector(1..0):= (others=>1);
+
+  function digits_sum (n : Positive) return Positive is
+  (if n < 10 then n else n mod 10 + digits_sum (n / 10));
+
+  function prime_factors (n : Positive; d : Positive := 2) return Vector is
+  (if n = 1 then empty_vector elsif n mod d = 0 then prime_factors (n / d, d) & d
+   else prime_factors (n, d + (if d=2 then 1 else 2)));
+
+  function vector_digits_sum (v : Vector) return Natural is
+  (if v'Length = 0 then 0 else digits_sum (v(v'First)) + vector_digits_sum (v(v'First+1..v'Last)));
+
+begin
+  for n in 1..10000 loop
+    declare
+      primes : Vector := prime_factors (n);
+    begin
+      if  primes'Length > 1 and then vector_digits_sum (primes) = digits_sum (n) then
+        Ada.Text_IO.put (n'img);
+      end if;
+    end;
+  end loop;
+end smith;