June 2018 Update

Task/Pernicious-numbers/Modula-2/pernicious-numbers.mod2

@@ -0,0 +1,50 @@
+MODULE Pernicious;
+FROM FormatString IMPORT FormatString;
+FROM Terminal IMPORT WriteString,WriteLn,ReadChar;
+
+PROCEDURE IsPrime(x : LONGINT) : BOOLEAN;
+VAR i : LONGINT;
+BEGIN
+    IF x<2 THEN RETURN FALSE END;
+    FOR i:=2 TO x-1 DO
+        IF x MOD i = 0 THEN RETURN FALSE END
+    END;
+    RETURN TRUE
+END IsPrime;
+
+PROCEDURE BitCount(x : LONGINT) : LONGINT;
+VAR count : LONGINT;
+BEGIN
+    count := 0;
+    WHILE x>0 DO
+        x := x BAND (x-1);
+        INC(count)
+    END;
+    RETURN count
+END BitCount;
+
+VAR
+    buf : ARRAY[0..63] OF CHAR;
+    i,n : LONGINT;
+BEGIN
+    i := 1;
+    n := 0;
+    WHILE n<25 DO
+        IF IsPrime(BitCount(i)) THEN
+            FormatString("%l ", buf, i);
+            WriteString(buf);
+            INC(n)
+        END;
+        INC(i)
+    END;
+    WriteLn;
+
+    FOR i:=888888877 TO 888888888 DO
+        IF IsPrime(BitCount(i)) THEN
+            FormatString("%l ", buf, i);
+            WriteString(buf)
+        END;
+    END;
+
+    ReadChar
+END Pernicious.