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📜 WAYPOINT LESSON

Checkpoint — OOP

⭐ beginner⏳ 20 min read📍 Lesson 41 of 85

A media library: a base `MediaItem`, audio and video specializations, and a contract-level player loop.

Checkpoint: the media library

Task: implement in Solution:

  1. Abstract class MediaItem — protected Title, public constructor throwing ArgumentException for null/whitespace title, read-only Title, public abstract int PlaySeconds();.
  2. Song(string title, int seconds) — returns seconds.
  3. Video(string title, int seconds, int speed) — playback at speed (1 = normal); PlaySeconds() returns the wall-clock time: seconds / speed (integer division is fine).
  4. static int TotalRuntime(List<MediaItem> items) — sum of PlaySeconds(); null/empty → 0.