n servers numbered from
n - 1 connected by undirected server-to-server
connections forming a network where
connections[i] = [ai, bi] represents a connection between servers
bi. Any server can reach other servers directly or indirectly through the network.
A critical connection is a connection that, if removed, will make some servers unable to reach some other server.
Return all critical connections in the network in any order.
Input: n = 4, connections = [[0,1],[1,2],[2,0],[1,3]] Output: [[1,3]] Explanation: [[3,1]] is also accepted.
Input: n = 2, connections = [[0,1]] Output: [[0,1]]
2 <= n <= 105
n - 1 <= connections.length <= 105
0 <= ai, bi <= n - 1
ai != bi