grokking_algorithms/06_breadth-first_search/Scala Solutions

package SearchAndSort

import scala.collection.immutable.HashMap
import scala.collection.{immutable, mutable}


object BreadthFirstSearch extends App {

  val graph  = HashMap(
    ("you" -> Vector("alice", "bob", "claire")),
    ("bob" -> Vector("anuj", "peggy")),
    ("alice" -> Vector("peggy")),
    ("claire" -> Vector("thom", "johnny")),
    ("anuj" -> Vector()),
    ("peggy" -> Vector()),
    ("thom" -> Vector()),
    ("jonny" -> Vector()),
  )

  def personIsSeller(name: String): Boolean =
    name.endsWith("y")

  def search(name: String): Unit = {
    var searchQue = mutable.Queue[String]()
    searchQue ++= graph(name)
    var searched = Array()
    var seller = false
    while (!seller) {
      val person = searchQue.dequeue()
      if (!searched.contains(person)){
        if (personIsSeller(person)) {
          println(person + " is a mango seller!")
          seller = true
        }
        else {
          searchQue ++= graph(person)
          searched + person
        }
      }
    }
  }

  println(search("you"))

  def searchFunctional(name: String): String = {
    var searchQue = immutable.Queue[String]()

    @scala.annotation.tailrec
    def helper(searchQue: immutable.Queue[String], searched: Vector[String] = Vector()): String = {
      if (searchQue.isEmpty) return "No Mango sellers"
      val person = searchQue.dequeue._1
      if (searched.contains(person))
        helper(searchQue.tail)
        else if (personIsSeller(person)) {
          val result: String = s"$person is a mango seller!"
          result
        } else
          helper(searchQue.tail ++ graph(person), searched :+ person)
      }
      helper(searchQue ++ graph(name))
    }

  println(searchFunctional("you"))
}