Hello I am trying to solve the question :http://www.spoj.com/problems/PT07Z/ in SPOJ. I have used bfs to find the leaf node and then used bfs again to find the maximum path.I am trying this approach and I don't know what is causing the error. Here is a link to my solution http://ideone.com/QSJzDf.
Your answer on this test is wrong. Paint this graph (at input section).
To solve this problem it is better to use "Adjacency lists", instead of "adjacency matrix". Your matrix g is too big and you create it using 8-bytes type "long long int" and on the stack.