feat: add function to count songs by artist

src/main/scala/TopSongs/TopSongs.scala

@@ -101,6 +101,18 @@ case class TopSongs(songs: List[Song] = List()) {
       }
     })
   }
+
+  // This function counts the number of songs by each artist
+  // 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] = {
+    songs.flatMap(_.singer.map(_.person.name))
+      .groupBy(identity)
+      .view.mapValues(_.size)
+      .toMap
+  }
+
 }
 
 @main def main(): Unit =
@@ -137,3 +149,13 @@ case class TopSongs(songs: List[Song] = List()) {
 
   // print the songs
   topSongs.printSongs()
+
+  println("----------");
+
+  // print the number of songs by artist
+  val songsByArtist = topSongs.countSongsByArtist(topSongs.songs)
+  println("Number of songs by artist:")
+  songsByArtist.foreach {
+    case (artist, count) => println(s"$artist: $count")
+  }
+