need help about 2-SAT problem

dfs
scc
twosat

#1

I am trying to learn 2-SAT. All I found is a google translated e-maxx.ru and a wekipedia page. But I could not understand all of them. I understand the graph construction and the impossible case, why and when it does not have solution. its clear to me . But I can not understand the topo sort / start time finish time part inside it. What else information can we extract form 2-SAT besides satisfiable/not?

http://codeforces.com/problemset/problem/228/E
I found this problem as an exercise of 2-SAT. As i mentioned I understand the graph construction and decision part but I can not understand the topo sort part for path printing (the order that ons all bits).
Tags 2-sat, dsu, topological sort, scc


#2

http://translate.google.ru/translate?sl=ru&tl=en&js=n&prev=_t&hl=ru&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Fe-maxx.ru%2Falgo%2F&act=url
this may help