Data update

Task/Additive-primes/Oberon-07/additive-primes.oberon

@@ -0,0 +1,51 @@
+MODULE AdditivePrimes;
+
+IMPORT
+  Out;
+
+CONST
+  Max = 500;
+
+VAR
+  Count, n :INTEGER;
+  Prime    :ARRAY Max + 1 OF BOOLEAN;
+
+PROCEDURE DigitSum( n :INTEGER ):INTEGER;
+  VAR   result    :INTEGER;
+  BEGIN
+    result := 0;
+    IF n < 10 THEN result := n
+    ELSE result := ( n MOD 10 ) + DigitSum( n DIV 10 )
+    END
+  RETURN result
+  END DigitSum;
+
+PROCEDURE Sieve;
+  VAR     i, j    :INTEGER;
+  BEGIN
+    Prime[ 0 ] := FALSE; Prime[ 1 ] := FALSE;
+    FOR i := 2 TO Max DO Prime[ i ] := TRUE END;
+    FOR i := 2 TO Max DIV 2 DO
+      IF Prime[ i ] THEN
+        j := i * 2;
+        WHILE j <= Max DO
+          Prime[ j ] := FALSE;
+          INC( j, i )
+        END
+      END
+    END
+  END Sieve;
+
+BEGIN
+  Sieve;
+  FOR n := 2 TO Max DO
+    IF Prime[ n ] & Prime[ DigitSum( n ) ] THEN
+      Out.Int( n, 4 );
+      INC( Count );
+      IF Count MOD 20 = 0 THEN Out.Ln END
+    END
+  END;
+  Out.Ln;Out.String( "There are " );Out.Int( Count, 1 );
+  Out.String( " additive primes less than " );Out.Int( Max, 1 );
+  Out.String( "." );Out.Ln
+END AdditivePrimes.