TITLE: Something New Every Day
AUTHOR: Eugene Wallingford
DATE: October 11, 2005  6:54 PM
DESC: Just when I think I have seen it all, a student does something fresh and strange.
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BODY:
I'm not a Way Old-Timer, but I have been teaching
at my current university for thirteen years.  In
that time, I have seen a lot of odd student programs:
wacky bugs, quirky algorithms, outlandish hacks, and
just plain funny code.  But today I saw a new one...

One of my colleagues is teaching our intro majors
course.  In the lab today, he asked students to write
some code, including a three-argument Java method to
return the minimum of the three.  The goal of this
exercise was presumably to test the students' ability
to consider multiple decisions, to write compound
boolean expressions, and most probably to write nested
<TT>if</TT> statements.

Here is my rendition of one student's extraordinary
solution:
<PRE>
    public int min( int x, int y, int z )
    {
        for (int i = Integer.MIN_VALUE; i &lt;= Integer.MAX_VALUE; i++)
            if ( i == x )
                return x;
            else if ( i == y )
                return y;
            else if ( i == z )
                return z;
    }
</PRE>

Sadly, the student didn't do this quite right, as
right would be for this approach.  The program did
not use <TT>Integer.MIN_VALUE</TT> and <TT>Integer.MAX_VALUE</TT>
to control its loop; it used hardcoded negative
and positive 2,000,000,000.  As a result, it had to
throw in a back-up <TT>return</TT> statement after
the <TT>for</TT>-loop to handle cases where the
absolute of all three numbers were greater than
2,000,000,000.   So, the solution loses points for
correctness, and a bit of luster on style.

But still -- wow.  No matter what instructors think
their students will think, the students can come up
with something out of left field.

I have to admit...  In a certain way, I admire this
solution.  It demonstrates creativity, and even applies
a pattern that works well in other contexts.  If the
student had been asked to write a method to find the
smallest value in a three-element unsorted array, then
brute force would not only have seemed like a reasonable
thing to do; it would have been the only option.  Why
not try it for <TT>int</TT>s?  (For us XP mavens:  Is
this algorithm the simplest thing that will work?)

One answer to the "Why not?" question comes at run time.
This method uses 12 seconds or so on average to find its
answer.  That's almost 12 seconds more than an
<TT>if</TT>-based solution uses. :-)

Students can bring a smile to an instructors face
most every day.
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