The problem with green colour ? What's it?

[hank]

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the green colour (a mix of blue and yellow) means a problem with multiple inputs and a special judge program. 

""....a special judge program.""

I don't understand......What??

[obayashi]

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""....a special judge program."" 

I don't understand......What??    

some problem may produce many best solutions and any one would be accepted. so judging the answer requires a special program, not doing simple text comparison or stream comparison.
and also, some problem are really NP problems, it's easy to find one solution but even hard to find the best. like problem 652 (eight puzzle), for such problem, any right (but not best) sulotion would be accepted...