Until the Battery Blinks Red

Very Hard — logic-grid deduction puzzle

Three engineers took turns on the practice track, counting how many laps their robots ran before the batteries gave out.

It was the day before the big races, and the practice track was busy from sunrise to sunset. Three engineers each got one slot on the track to try out their robot's legs. The rule was simple: let the robot run until its battery blinked red, then count the laps. One robot wobbled on every bend, one waved at the crowd, and one kept chasing a volunteer's bicycle. Between runs, each engineer grabbed a snack from the volunteers' cart and jotted the lap count on a paper cup. By nightfall the cups were in the bin, and nobody could remember who had run what, or when.

Clues

1. Only two of these three things were true: Lan looked after Pangpang; Jun looked after Xiaobao; Jun had the noon slot.
2. The robot that ran 20 laps had the slot right before the 12-lap robot's.
3. Xiaobao ran 6 laps.
4. The noon slot did not go to whoever ate noodles.
5. Of these three things, only two were true: the evening slot went to the robot that ran 6 laps; whoever ate dumplings had the evening slot; Doudou's engineer ate noodles.
6. Of Mei and whoever ate buns, one had the robot that ran 6 laps and the other had the robot that ran 12 laps.

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