Waiting for Applause

Hard — logic-grid deduction puzzle

Three engineers look back on how their robots did at a sorting trial that ended up drawing a clapping crowd.

The races pulled in the big crowds, but one corner of the arena had a smaller show of its own: a sorting trial. Three engineers each ran a different robot. Each robot sorted a different kind of object into a tray of a different colour. At the end, each robot had a different count, the number of items it had placed safely in its tray. One of the robots stopped after every drop, as if it were waiting for applause. The people watching soon caught on, and they clapped every time.

Clues

1. Only one of these was true: Tao's robot sorted the balls; the 25 items were blocks; the 3 items went into the yellow tray.
2. Only one of these three things happened: Diandian worked at the blue tray, Yue's robot worked at the yellow tray, or Tuantuan sorted 3 items.
3. Of Tuantuan and Diandian, one was run by Min and the other used the yellow tray.
4. At least one of these was true: the balls went into the yellow tray, or Doudou sorted 20 items.
5. Tuantuan did not sort the balls.
6. Of the robots Tao and Min ran, one sorted 20 items and the other sorted the balls.

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