Is it the case, for any given input list, that there can only be one correct division of elements into two lists? Or are multiple alternatives acceptable?

And is it really the case that the input list will always consist of integer multiples of 5?

If the latter answer is "yes", and you're not too picky about the nature of the partitioning, this ought to do fine:

@input = (5, 10, 20, 25, 30, 40, 45, 50, 55, 65, 75, 80, 90);

@out1 = grep /5$/, @input;
@out2 = grep /0$/, @input;
[download]

If that's not suitable, you'll need to be clearer about what the other constraints are for the partition.

---

---

• Are you posting in the right place? Check out Where do I post X? to know for sure.
• Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:

  <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>

• Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
• Want more info? How to link or How to display code and escape characters are good places to start.