Refrigerator Madness is the second Facebook programming puzzle I have tried. The problem description is complicated. I won't try to repeat it here but to suggest you to refer to the original facebook page.
To solve this problem it is necessary to see through the smokescreen. Instead of thinking how much Red Bull a Facebook engineer likes to drink, it is easier to map it to a problem known as Two-Sided Matching. A model with intuitive meaning is a marriage matchup between a group of man and woman. Each man has his list of preferred woman and each woman has her list of preferred man. The marriage is considered stable if there are no two people of opposite sex who were not married to each other but would both prefer to be.
For the Refrigerator Madness problem just map the engineer from the upper 50th percentile to "man" and lower 50th percentile to "woman" (or vice versa). The matching condition is equivalent to the stable marriage criteria.
At this point the problem can be solved by applying the Gale-Shapley algorithm. Write the code and it's done!
2010.02.22 - comments
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