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Discussion of Problem 1575. Yekaterinburg Subway 2

1905_year_square??
Posted by strider 3 Feb 2009 17:04
There is TWO 1905_year_square:
1st is yellow-red
2nd is purple-green
and there is no transition between them! Am i right? Then stations (graph vertices) count to 71. And the path from
"Shevchenko" to "1905_year_square" is 1 or 2 depending where we go!

So, i also have WA#2 and think maybe here is my fault...
Re: 1905_year_square??
Posted by Sandro (USU) 4 Feb 2009 00:38
No, you are wrong. 1905_year_square is an intersection of 4 lines: yellow, red, purple and green.
Re: 1905_year_square??
Posted by strider 4 Feb 2009 03:41
Yes, thanks.

But the picture is tangling. Two-colored circles must have suggested that there is a transition between two stations if there exists a circle with sectors of the two colors. This condition is true everywhere except 1905_year_square.
On the other hand, there is no circle where yellow and green branches come and outcome together (what could be another intuitive criteria). So there is no reason to consider the two disputable circles as one station but their nearness.