There is a problem but I didn't find it in codeforces. If you can help me to find it and solve it.
n cities and
m road between them. roads are two-way. Capital is city
z. We define city
x critical for city
y if all the ways for going from
x. If we want to find that
x is critical for
y or not, an easy way is to use dfs to find that is there any way from capital to
y or not. then do another dfs but
x removed from graph (avoid dfs from going to
x). based on this two dfs, we can understand that x is critical or not for
However in this new problem we want to find number of critical cities. (all
y). However I don't remember that there is a capital or not. if there is no capital, then we must try all
z too. If we do last idea, there is a time limit. I want a better way.
I didn't found problem in codeforces but I know that exists in codeforces, I just don't save it!
Is it possible to help me?
I'm sorry for bad English. Thanks.