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Raw Recruits 
Project Description Prerequisites Warm up Problems Hints Resources Teaching Notes Extension Problems Results

Hints for Raw Recruits

1.  When you start a problem, it's often useful to consider different ways to look at it.  An "alternate representation" will often save you time or might even give you a new insight into the problem.   While working on Raw Recruits, have you been drawing little soldiers?   You can save yourself some time by using simple symbols instead.  For example "<" and ">" are a lot easier to draw to represent left and right facing recruits.   Here is how the original example would evolve with this representation.

You might get even more insight into the problem if you use other symbols in your representation instead of  < and >.  For a further discussion of representations, click here.

2.  There is at least on thing that doesn't change as the recruits react to one another.  Can you identify that invariant?  It should help you identify and prove what the final configuration will be for any initial configuration.

What's left and what's right?   From now on, we'll use the sergeant's perspective of what's right and left.   When he said "left face" he wanted to see them facing to his right, as almost all of the recruits did.  We've found that once people start thinking about this problem, most want to use this perspective.

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