When I saw the naive bridge finding algorithm (PR #54), I expected a non-naive version as well.
There is a version by Tarjan (https://en.wikipedia.org/wiki/Bridge_%28graph_theory%29#Tarjan.27s_Bridge-finding_algorithm).
There is also an easier version on the internet (http://stackoverflow.com/a/28917697/262526), but unfortunately I was unable to find the original source for this.

Anyone willing to implement this?