How i can walk on these 7 bridges without walk on one of them twice?
After some research i found that "Koengsberg bridge" is not an Euler circuit.
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1$\begingroup$ It's not possible... $\endgroup$– somebodyOct 20, 2017 at 0:01
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$\begingroup$ @Ibrahim, if it isn't immediately obvious that the question we've marked this as a duplicate of is basically the same as this one, follow the "Seven Bridges of Koenigsberg" link in either the first comment under the question or GoodDeed's answer. $\endgroup$– Gareth McCaughan ♦Oct 20, 2017 at 0:41
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1$\begingroup$ Since the question was "How i can walk on these 7 bridges without walk on one of them twice?", one of the solution is if you can swim(walk B-A-B-D-B-C-D, swim to A, walk A-C). Since you only said walk(not cross), you can walk B-A-B-D-B-C, walk halfway the C-A bridge, turn back in the middle, go back to C, walk C-D. $\endgroup$– NopalaaOct 20, 2017 at 8:03
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I say it's impossible to walk on these 7 bridges without walk on one of them twice.
As the picture shows, each island has either 3 or 5 bridges connected to it, that's why I declare it impossible to walk on these 7 bridges without walk on one of them twice.
There's a proper proof out there that shows that: To walk on bridges only once each, EACH island must have an EVEN number of bridges connected to it. Or exactly 2 have an odd number of bridges connected.
Here, we have 4 islands having an odd number of bridges connected. So it's impossible to walk on these 7 bridges without walk on one of them twice.
