Enum attr
    Colour = 1
    Nationality
    Beverage
    Smoke
    Pet
End Enum

Enum Drinks_
    Beer = 1
    Coffee
    Milk
    Tea
    Water
End Enum

Enum nations
    Danish = 1
    English
    German
    Norwegian
    Swedish
End Enum

Enum colors
    Blue = 1
    Green
    Red
    White
    Yellow
End Enum

Enum tobaccos
    Blend = 1
    BlueMaster
    Dunhill
    PallMall
    Prince
End Enum

Enum animals
    Bird = 1
    Cat
    Dog
    Horse
    Zebra
End Enum

Const factorial5 = 120
Dim Shared As String permutation(120), perm(5)
Dim Shared As String Colours(5), Nationalities(5), Drinks(5), Smokes(5), Pets(5)
Dim Shared As Integer index

Sub generate(n As Integer, A() As Integer)
    Dim As Integer i
    If n = 1 Then
        Dim tmp As String = ""
        For i = 1 To 5
            tmp &= Str(A(i)) & " "
        Next i
        permutation(index) = tmp
        index += 1
    Else
        For i = 1 To n
            generate(n - 1, A())
            If n Mod 2 = 0 Then
                Swap A(i), A(n)
            Else
                Swap A(1), A(n)
            End If
        Next i
    End If
End Sub

Function house(i As Integer, nombre As Integer) As Integer
    For x As Integer = 1 To 5
        If Val(Mid(perm(i), x * 2 - 1, 1)) = nombre Then Return x
    Next x
    Return 0
End Function

Function left_of(h1 As Integer, h2 As Integer) As Boolean
    Return (h1 - h2) = -1
End Function

Function next_to(h1 As Integer, h2 As Integer) As Boolean
    Return Abs(h1 - h2) = 1
End Function

Sub print_house(i As Integer)
    Print Using "####: "; i;
    Print Using "\    \  \       \  \    \  \       \  \    \"; _
    Colours(Val(Mid(perm(Colour), i * 2 - 1, 1))); _
    Nationalities(Val(Mid(perm(Nationality), i * 2 - 1, 1))); _
    Drinks(Val(Mid(perm(Beverage), i * 2 - 1, 1))); _
    Smokes(Val(Mid(perm(Smoke), i * 2 - 1, 1))); _
    Pets(Val(Mid(perm(Pet), i * 2 - 1, 1)))
End Sub

Sub Zebra_puzzle()
    Colours(1) = "blue": Colours(2) = "green": Colours(3) = "red": Colours(4) = "white": Colours(5) = "yellow"
    Nationalities(1) = "Dane": Nationalities(2) = "English": Nationalities(3) = "German": Nationalities(4) = "Norwegian": Nationalities(5) = "Swede"
    Drinks(1) = "beer": Drinks(2) = "coffee": Drinks(3) = "milk": Drinks(4) = "tea": Drinks(5) = "water"
    Smokes(1) = "Blend": Smokes(2) = "Blue Master": Smokes(3) = "Dunhill": Smokes(4) = "Pall Mall": Smokes(5) = "Prince"
    Pets(1) = "birds": Pets(2) = "cats": Pets(3) = "dog": Pets(4) = "horse": Pets(5) = "zebra"

    Dim As String solperms(120, 5)
    Dim As Integer solutions, i, c, n, d, s, p, j
    Dim As Integer b(5)
    For i = 1 To 5: b(i) = i: Next
    'There are five houses.
    index = 0
    generate(5, b())
    For c = 0 To factorial5 - 1
        perm(Colour) = permutation(c)
        'The green house is immediately to the left of the white house.
        If left_of(house(Colour, Green), house(Colour, White)) Then
            For n = 0 To factorial5 - 1
                perm(Nationality) = permutation(n)
                'The Norwegian lives in the first house.
                'The English man lives in the red house.
                'The Norwegian lives next to the blue house.
                If house(Nationality, Norwegian) = 1 _
                And house(Nationality, English) = house(Colour, Red) _
                And next_to(house(Nationality, Norwegian), house(Colour, Blue)) Then
                    For d = 0 To factorial5 - 1
                        perm(Beverage) = permutation(d)
                        'The Dane drinks tea.
                        'They drink coffee in the green house.
                        'In the middle house they drink milk.
                        If house(Nationality, Danish) = house(Beverage, Tea) _
                        And house(Beverage, Coffee) = house(Colour, Green) _
                        And house(Beverage, Milk) = 3 Then
                            For s = 0 To factorial5 - 1
                                perm(Smoke) = permutation(s)
                                'In the yellow house they smoke Dunhill.
                                'The German smokes Prince.
                                'The man who smokes Blue Master drinks beer.
                                'They Drink water in a house next to the house where they smoke Blend.
                                If house(Colour, Yellow) = house(Smoke, Dunhill) _
                                And house(Nationality, German) = house(Smoke, Prince) _
                                And house(Smoke, BlueMaster) = house(Beverage, Beer) _
                                And next_to(house(Beverage, Water), house(Smoke, Blend)) Then
                                    For p = 0 To factorial5 - 1
                                        perm(Pet) = permutation(p)
                                        'The Swede has a dog.
                                        'The man who smokes Pall Mall has birds.
                                        'The man who smokes Blend lives in the house next to the house with cats.
                                        'In a house next to the house where they have a horse, they smoke Dunhill.
                                        If house(Nationality, Swedish) = house(Pet, Dog) _
                                        And house(Smoke, PallMall) = house(Pet, Bird) _
                                        And next_to(house(Smoke, Blend), house(Pet, Cat)) _
                                        And next_to(house(Pet, Horse), house(Smoke, Dunhill)) Then
                                            For i = 1 To 5
                                                print_house(i)
                                            Next i
                                            Print
                                            solutions += 1
                                            For j = 1 To 5
                                                solperms(solutions - 1, j - 1) = perm(j)
                                            Next j
                                        End If
                                    Next p
                                End If
                            Next s
                        End If
                    Next d
                End If
            Next n
        End If
    Next c

    Print solutions & " solution" & Iif(solutions > 1, "s", "") & " found"
    For i As Integer = 0 To solutions - 1
        For j As Integer = 1 To 5
            perm(j) = solperms(i, j - 1)
        Next j
        Print "The " & Nationalities(Val(Mid(perm(Nationality), house(Pet, Zebra) * 2 - 1, 1))) & " owns the Zebra"
    Next i
End Sub
Print "House Colour  Nation     Drink   Smoke      Animal"

Zebra_puzzle()

Sleep