Hi Codeforces authority,

I request you to arrange contests on weekends if possible. Like me, many contestants are working on week days. It is very hard for me to attend weekdays contests. So, if you consider the problem, please try to arrange contests on weekends (Saturday or Sunday or any middle time between Sat and Sun). Though I am not a good contestant, still I believe this will encourage more people like me!

Thanks for all of your patience!

[EDIT] It is Codeforces Round — 270, not SRM-270. Sorry for mixing up with TopCoder!

My understanding of the problem as below: A matrix is given where each entry (row,col) represents weight of an edge from row to col. We have to check if the matrix can be represented as a weighted tree.

So, I think, there are two things to check. If a node has a positive edge (weight>0) to itself, then it is not a weighted tree. If weight[u,v] != weight[v,u], then it is also not a weighted tree.

Are these conditions sufficient? I think NO. But, I am not getting what else should we check. I googled about "weighted tree" to gain some knowledge. I found that it is a tree simply weights are given for every edge. Am I missing something?

If anyone can clarify the problem description and the missing parts of my knowledge about weighted tree, I will be grateful!

Thanks!

Hi,

Sorry for this non Algorithmic post. I cannot see my name in the list of my country. I have given my full address including country name and logged out-in. But still cannot see my name in the list. Is there anything I am missing to do? Thanks for your help.

late_riser