That time you worked in that fast food place—what was it called?—your job during lunch rush hour was to keep those two people supplied with tortillas. Each of them had a bin of tortillas, and they’d grab the tortillas from the bin and use them as the base of whatever they were assembling.

Anyway, for the whole of rush hour the assemblers together needed three bins of tortillas. You found a way to keep both assemblers busy without having to move tortillas from one bin to another: You’d let the first assembler get half way through a bin, and then replace it with the third bin, which was full. When the second assembler ran out, you’d replace that bin with the remainder of the first assembler's bin. So both assemblers came out even at the end.

Then that new factory opened up down the street, so the lunch rush became even busier. They put on a third assembler for you to supply. You quickly found that over lunch hour those three assemblers needed five bins of tortillas. Was it still possible to keep all assemblers working steadily without having to move tortillas between the bins?




Table, bins as columns

Table, workers as columns

Describe a method that will always work.

Your experience

Have you used this problem with a class and seen approaches other than(or more specific than) those mentioned above? Or do you have other comments or criticisms or stories? If so, please tell us!

Last updated 30 November, 2004