Social Network
Polycarpus got an internship in one well-known social network. His test task is to count the number of unique users who have visited a social […]
Social Network
New Year and Social Network
Donghyun’s new social network service (SNS) contains $n$ users numbered $1, 2, \ldots, n$. Internally, their network is a tree graph, so there are $n-1$ direct […]
