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12 lines
746 B
12 lines
746 B
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Exercise 4.40: In the multiple dwelling problem,
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how many sets of assignments are there of people to floors, both before and
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after the requirement that floor assignments be distinct? It is very
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inefficient to generate all possible assignments of people to floors and then
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leave it to backtracking to eliminate them. For example, most of the
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restrictions depend on only one or two of the person-floor variables, and can
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thus be imposed before floors have been selected for all the people. Write and
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demonstrate a much more efficient nondeterministic procedure that solves this
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problem based upon generating only those possibilities that are not already
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ruled out by previous restrictions. (Hint: This will require a nest of
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let expressions.)
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