Google (Senior) Software Engineer interview questions

Find the longest path that passes through every one of a tree.

They would ask randomised questions. Hence it would be different for each person. For me they asked me about this general knowledge question, “ you are going for Golf, you bring along 8 Golf balls with you. But then there is a one ball that is slightly heavier, but you couldn’t tell. You have a balance beam but could only do 2 weighings, how do you find which is the heavier ball?