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http://rosettacode.org/wiki/Dinesman's_multiple-dwelling_problem
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import java.util.HashSet

■ Dinesman
  § static

    houses⦂ HashSet⟨String⟩°

    ▶ main
    • args⦂ String[]
      · Baker, Cooper, Fletcher, Miller, and Smith …
      build *StringBuilder°, *StringBuilder "BCFMS"
      ∀ house ∈ houses⦂ String
        if verify house
           System.out.println house.toString°

    ▶ verify⦂ boolean
    • house⦂ String
      · Baker does not live on the top floor.
      return false if house.charAt 4 = 'B'
      · Fletcher does not live on either the top or the bottom floor.
      return false if house.charAt 0 = 'F' or house.charAt 4 = 'F'
      · Cooper does not live on the bottom floor.
      return false if house.charAt 0 = 'C'
      · Miller lives on a higher floor than does Cooper.
      return false if house.indexOf "M" ≤ house.indexOf "C"
      · Smith does not live on a floor adjacent to Fletcher's.
      return false if Math.abs (house.indexOf "S") - (house.indexOf "F") = 1
      · Fletcher does not live on a floor adjacent to Cooper's.
      return false if Math.abs (house.indexOf "F") - (house.indexOf "C") = 1
      return true

    ▶ build
    • house⦂ StringBuilder
    • people⦂ StringBuilder
      if people.length° = 0
         houses.add house.toString°
      else
         ∀ i ∈ 0…people.length°
           person⦂ char: people.charAt i
           house.append person
           people.deleteCharAt i
           build house, people
           people.insert i, person
           house.setLength house.length° - 1