Add TT3.java

Miscellaneous/TT3.java

@@ -0,0 +1,47 @@
+import java.util.*;
+
+interface Playlist {
+    Song getNextSong();
+
+    boolean hasNextSong();
+}
+
+class Song {
+    String name;
+
+    public Song(String name) {
+        this.name = name;
+    }
+}
+
+class CollaborativePlaylist implements Playlist {
+    private Deque<Playlist> dq;
+
+    public CollaborativePlaylist(List<Playlist> playlists) {
+        dq = new ArrayDeque<>();
+
+        for (Playlist p : playlists) {
+            dq.offer(p);
+        }
+    }
+
+    @Override
+    public Song getNextSong() {
+        while (!dq.isEmpty()) {
+            Playlist p = dq.pollFirst();
+
+            if (p.hasNextSong()) {
+                Song s = p.getNextSong();
+                dq.offerLast(p);
+                return s;
+            }
+        }
+
+        return null;
+    }
+
+    @Override
+    public boolean hasNextSong() {
+        return !dq.isEmpty();
+    }
+}