in reply to Re: Recursion Alternatives?
in thread Recursion Alternatives?

To help you on your way, here's a recursive solution for merge sort: 
    sub merge {
        my ($f, $s, @r) = @_;
        push @r => shift @{$$f [0] < $$s [0] ? $f : $s} while @$f && @
+$s;
       (@r, @$f, @$s);
    }
    sub merge_sort;
    sub merge_sort {
        @_ <= 1 ? @_ : merge [merge_sort @_ [0 .. @_ / 2 - 1]],
                             [merge_sort @_ [@_ / 2 .. $#_]]
    }

[download]

The recursive solution is elegant, and just 10 lines. I don't really want to think about the iterative solution.

Abigail

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Re: Re: Recursion Alternatives?
by BrowserUk (Patriarch) on Feb 27, 2003 at 11:07 UTC

    Is there any particular significance to your choice of $f, $s and @r as variable names? They don't seem to match up with the classic left, right and temp in either english or dutch?

    ..and remember there are a lot of things monks are supposed to be but lazy is not one of them

    Examine what is said, not who speaks.
    1) When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.
    2) The only way of discovering the limits of the possible is to venture a little way past them into the impossible
    3) Any sufficiently advanced technology is indistinguishable from magic.
    Arthur C. Clarke.
[reply]
      first, second, result.

      Abigail

[reply]

        I just updated my post, but you may not see it, you have an extraneous ']' in the merge_sort sub.

        ..and remember there are a lot of things monks are supposed to be but lazy is not one of them

        Examine what is said, not who speaks.
        1) When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.
        2) The only way of discovering the limits of the possible is to venture a little way past them into the impossible
        3) Any sufficiently advanced technology is indistinguishable from magic.
        Arthur C. Clarke.
[reply]

In Section Meditations