test.scala

  def maxShared(friendsNodes: Int, friendsFrom: Array[Int], friendsTo: Array[Int], friendsWeight: Array[Int]): Int = {

    val allNodesFrom = friendsFrom ++ friendsTo
    val allWeights = friendsWeight ++ friendsWeight
    val allNodesTo = friendsTo ++ friendsFrom


    val nodeToNodeOverInterest = allNodesFrom
      .zipWithIndex
      .foldLeft(Map[Int, Map[Int, Set[Int]]]())((acc, p) => {
        val interest = allWeights(p._2)
        val peer = allNodesTo(p._2)
        val currentConnections = acc.getOrElse(p._1, Map[Int, Set[Int]]())
        val currentConnectionsOverInterest = currentConnections.getOrElse(interest, Set.empty)
        val newConnectionsOverInterest = interest -> (currentConnectionsOverInterest + peer)
        val newConnections = currentConnections + newConnectionsOverInterest
        acc + (p._1 -> newConnections)
      })

    def isNodeConnectedOverInterest(n1: Int, n2: Int, interest: Int, intermediatePeers: Set[Int]): Boolean = {
      val connections = nodeToNodeOverInterest(n1).getOrElse(interest, Set.empty)
      connections.contains(n2) match {
        case true => true
        case false if connections.subsetOf(intermediatePeers) => false
        case _ =>
          val possiblePaths = connections -- intermediatePeers
          possiblePaths.foldLeft(false)((acc, p) => acc || isNodeConnectedOverInterest(p, n2, interest, intermediatePeers ++ connections))
      }
    }

    val pairsWithNumberOfConnections = (1 to friendsNodes)
      .combinations(2)
      .toList
      .map(p => {
        val firstNode = p(0)
        val secondNode = p(1)
        val numberOfConnections = friendsWeight.toSet.toList.map(intr => isNodeConnectedOverInterest(firstNode, secondNode, intr, Set.empty)).filter(p => p).size
        (p, numberOfConnections)
      })

    val maxConnections = pairsWithNumberOfConnections.map(_._2).max
    val pairsWithMaxNumOfConnections = pairsWithNumberOfConnections.filter(_._2 == maxConnections).map(_._1)
    pairsWithMaxNumOfConnections.map(p => p(0) * p(1)).max
  }