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From: tim@ism780c.UUCP (Tim Smith)
Newsgroups: net.puzzle
Subject: Re: 5 boxes
Message-ID: <419@ism780c.UUCP>
Date: Mon, 3-Feb-86 17:27:51 EST
Article-I.D.: ism780c.419
Posted: Mon Feb  3 17:27:51 1986
Date-Received: Wed, 5-Feb-86 02:29:24 EST
References: <1146@ecsvax.UUCP>
Reply-To: tim@ism780c.UUCP (Tim Smith)
Distribution: net
Organization: Interactive Systems Corp., Santa Monica, CA
Lines: 30

In article <1146@ecsvax.UUCP> hal@ecsvax.UUCP writes:
>
>Here is a diagram consisting of five squares, two on top and three on
>bottom.  It has been divided into 16 lines, which I have numbered as
>shown:
>
>
>   _____1____________2____
>  |           |           |
> 3|          4|          5|
>  |___6____7__|__8_____9__|
>  |      |         |      |
>10|    11|       12|    13|
>  |______|_________|______|
>     14       15      16
>
>
>The object is to draw a single line that crosses all of the 16 lines
>in the figure once and only once.  The line may start inside or outside
>the figure, and it may not cross itself.

Note that the two top squares each have five lines that must be crossed,
as does the bottom middle square.  Note also that the when you enter and
leave a square, you cross two lines.  Thus the only way to cross all the
lines on a square with an odd number of lines is to have one of the ends
be in that square.  Now we have three squares with an odd number, but we
only have two endpoints, thus it can't be done.

--
Tim Smith       sdcrdcf!ism780c!tim || ima!ism780!tim || ihnp4!cithep!tim