Euler 857 - please clarify the notion of a cycle

A place to air possible concerns or difficulties in understanding ProjectEuler problems. This forum is not meant to publish solutions. This forum is NOT meant to discuss solution methods or giving hints how a problem can be solved.
Forum rules
As your posts will be visible to the general public you are requested to be thoughtful in not posting anything that might explicitly give away how to solve a particular problem.

This forum is NOT meant to discuss solution methods for a problem.

In particular don't post any code fragments or results.

Don't start begging others to give partial answers to problems

Don't ask for hints how to solve a problem

Don't start a new topic for a problem if there already exists one


See also the topics:
Don't post any spoilers
Comments, questions and clarifications about PE problems.
Post Reply
FritzF
Posts: 2
Joined: Sun Oct 01, 2023 1:29 pm

Euler 857 - please clarify the notion of a cycle

Post by FritzF »

To me, the notion of "cycle" is unclear in this problem.
I do not see the difference between the second case on the top row vs the second case on the bottom row.
FritzF
Posts: 2
Joined: Sun Oct 01, 2023 1:29 pm

Re: Euler 857 - please clarify the notion of a cycle

Post by FritzF »

I withdraw the question, assuming that cycles are meant to go through at least 3 vertices.
__ngn__
Posts: 2
Joined: Mon Aug 21, 2023 10:03 pm

Re: Euler 857 - please clarify the notion of a cycle

Post by __ngn__ »

assuming that cycles are meant to go through at least 3 vertices
A 2-cycle always satisfies the condition for beauty, as it can only be made of the two arrows in a blue-red multi-edge. But, I guess, the second sample graph in the bottom row has more cycles, consisting of 3 vertices: the red-green-brown cycle and the blue-brown-green cycle. Those don't satisfy the condition.

If this interpretation is correct, it may be more clear if green and brown edges are described as "bidirectional" instead of "undirected".
Image
Post Reply