Algorithm To Scan For Different Colored Objects

[Mastermime]

Hey guys,

Does anyone know of a algorithm to scan for different colored pieces of paper along the floor in three different rooms? I have a bump and light sensor.  So I was thinking I could scan the room in lines and then once it hits a wall, the bump sensor will activate and turn it 180 degrees (similar to how you mow your lawn).  The only problem with this is that it could go into the next room without sensing the different piece of colored paper.  What are your guys thoughts?  Is there a better algorithm?