One day, the chief of the dwarves determined he needed to check his tribe. So that evening, he advised the dwarves that he would paint on every dwarf’s again a dot coloured both purple or blue. Each dwarf will know everybody else’s dot coloration, however not their very own.

Every dwarf with a purple dot on his or her again is to go to the eating corridor on the N^th day, the place N is the variety of dwarves with a purple dot on their backs. The presence of any blue-dotted dwarves on the eating corridor on the N^th day constitutes a failure.

Furthermore, after the dwarves get their backs painted, they aren’t allowed to speak utilizing any means, together with (however not restricted to) talking, punching, and holding mirrors. No dwarf is allowed to know what coloration he’s till after the trial is over. They don’t additionally get to know if somebody went to the corridor on any of the 1 to N-1 days.

The dwarves can meet on the day earlier than the trial to be able to speak technique. What technique ought to they use?

Note the query just isn’t the identical because the blue-eyes puzzle . In the blue eyes puzzle, one would get get to know if somebody went to the corridor on days 1 to N-1 .Here, no one will get to know this. This is an important distinction.