refactor: simplify function signatures for counting songs and retrieving top N songs

src/main/scala/TopSongs/TopSongs.scala

@@ -106,7 +106,7 @@ case class TopSongs(songs: List[Song] = List()) {
   // It uses flatMap to extract the artist names from the songs
   // Then it groups the songs by artist name and counts the occurrences
   // Finally, it returns a map with the artist names as keys and the counts as values
-  def countSongsByArtist(songs: List[Song]): Map[String, Int] = {
+  def countSongsByArtist(): Map[String, Int] = {
     songs.flatMap(_.singer.map(_.person.name))
       .groupBy(identity)
       .view.mapValues(_.size)
@@ -115,7 +115,7 @@ case class TopSongs(songs: List[Song] = List()) {
 
   // This function returns the top N songs by weeks on chart
   // It sorts the songs by the streak value in descending order and takes the top N songs
-  def topNSongsByWeeks(songs: List[Song], n: Int): List[Song] = {
+  def topNSongsByWeeks(n: Int): List[Song] = {
     songs.sortBy(song => -song.rank._1.streak.getOrElse(0)).take(n)
   }
 
@@ -156,19 +156,20 @@ case class TopSongs(songs: List[Song] = List()) {
   // print the songs
   topSongs.printSongs()
 
-  println("----------");
+  println("----------")
 
   // print the number of songs by artist
-  val songsByArtist = topSongs.countSongsByArtist(topSongs.songs)
+  val songsByArtist = topSongs.countSongsByArtist()
   println("Number of songs by artist:")
   songsByArtist.foreach {
     case (artist, count) => println(s"$artist: $count")
   }
 
   println("----------");
+  println("----------")
 
   // print the top N songs by weeks on chart
-  val topNSongs = topSongs.topNSongsByWeeks(topSongs.songs, 5)
+  val topNSongs = topSongs.topNSongsByWeeks(5)
   println("Top N songs by weeks on chart:")
   topNSongs.foreach { song =>
     println(s"${song.title} by ${song.singer.map(_.person.name).mkString(", ")} - ${song.rank._1.streak.getOrElse(0)} weeks")