Just one last minor point. A Google search on Warnsdorff revealed  
that it's HC Warnsdorff, not JC, and that its usually referred to as  
the Warnsdorff rule, not Warnsdorff heuristic. The latter is probably  
because "rule" is a lot easier to type than "heuristic" :D

Regards, Morton

On Aug 17, 2006, at 2:57 PM, James Edward Gray II wrote:

> On Aug 17, 2006, at 9:23 AM, Morton Goldberg wrote:
>
>>> The downside of the JC Warnsdorff heuristic is that is doesn't  
>>> always work.
>>> Depending on your starting position and which squares you visit  
>>> first, it can
>>> paint itself into a corner.  The problem is more common on  
>>> certain board sizes,
>>> but it does happen.  The upside is, it's so darn quick (because  
>>> it doesn't
>>> backtrack), you can do multiple searches and still be quicker  
>>> than the brute
>>> force approach.  If one attempt fails, just try again.  Most  
>>> solutions used this
>>> approach.
>>
>> Re: ... because it doesn't backtrack ...
>>
>> The heuristic can be used to improve a backtracking solver.
>
> That's a good point.  David Tran's solution does both.