Persons 1-5 occupy houses (in that order) on a ring road. The houses are painted amber, blue, chartreuse, denim and ecru (not necessarily in that order).

Fact 1. Person #1 presently lives in a house that is neither ecru nor denim.

Fact 2. One and only one of Person #1 and Person #3 presently live next to the blue house.

Fact 3. Some time ago, two people switched houses. As a result of the switch, one and only one of Person #2 and Person #4 got a new neighbour.

Fact 4. Either both of amber’s neighbours were changed in the switch, or else both of amber's neighbours remained unchanged.

Who lives in the chartreuse house?

Note: Aus dem Haeuschen is German slang. Haeuschen, (cottage) is used as a metaphor for for "brain". Thus, Aus dem Haeuschen means, more or less, out of one's mind, in the sense of being enthusiastic about something.

Clarification: Each person (and each house) has two neighbours, namely the person living to the left and the right. If the left neighbour and the right neighbour change houses, the occupant in the middle does not get any new neighbours.

From Fact 3 we can deduce the original order of the houses (before the switch) as one of the following:
12543, 12354, 21345, or 32145.

We know, from the preamble, our present arrangement of the colored houses is 12345.

From Fact 4 we can reduce our selection further with either #2 (32145) or #4 (12543) having an amber house.

From Fact 2, with #5 also adjacent to #1 on the ring road, we can determine that the blue house is occupied by #4 (adjacent to #3) or #5 (adjacent to #1).

#1's house is not amber as it is the color of #2 or #4 (Fact 3 and Fact 4).
#1's house is not blue as it the color of #4 or #5 (Fact 2).
#1's house is not denim or ecru (Fact 1).
#1's house must then be chartreuse.

Chartreuse is a variable color averaging a brilliant yellow green.

Posted by Dej Mar on 2008-03-05 20:29:33