You have now seen several advanced greedy problems. Common patterns:
Monotonic stack:: Remove K digits, Create Maximum Number. Use a stack to maintain some order property.
Range extension:: Patching Array. Track what you can achieve, greedily extend.
Simulation with greedy phases:: Candy Crush. Apply greedy logic at each step of a simulation.
Transformation to known problem:: Arrows to Activity Selection. Recognize a familiar problem in disguise.
Sort and process:: Make Unique. Sorting reveals structure that enables greedy.