Count number of chain reactions

Question

Suppose there is a new social page like facebook but every time someone publishes something, the publication automatically is re-published by all it's friends. This function causes a chain reaction, causing every friends of the first person's friends to also re-publish it and so on.

The publication can be done only once from every user.

Is there any graph algorithm that I could use to count the total number of the publications/republications and how?

score 0 · Answer 1 · answered Dec 11 '20 at 20:41

Easiest algorithm seems to be to store 3 lists:

one with all people who did not publish the post (at start everyone except the root person)
one with people who did publish the post but did not chain-react their friends (initial only root person)
one with people who did publish and chain-react to their friends (empty at first).

The algorithm would look something like

as long as there are people in the 2nd list:  
  choose one person P from 2nd list  
  find all friends of P within the first group and move them to the second group 
  move P to the third group 
when you are finished return the size of the 3rd group.

yes, you could use dijkstras algorithm, which is basically the same as the described one. — DuDa, Dec 13 '20 at 14:43

Count number of chain reactions

1 Answers1