Worked solutions to all 1114 exercises and problems in CLRS Introduction to Algorithms (3rd ed.), with proofs, running times and tested code. Free PDF.
Algorithms
Worked solutions to all 236 exercises in Kleinberg & Tardos's Algorithm Design, each with an algorithm, a correctness proof and a running-time bound. Free PDF.
Kleinberg & Tardos's Algorithm Design (Addison-Wesley, 2005): book notes, with worked solutions to all 236 end-of-chapter exercises.
Notes on all 23 Gang of Four design patterns — creational, structural and behavioural — each with its UML structure, when to use it, a worked example and its relations to the other patterns. Based on Shvets' Dive into Design Patterns.
naturally, the credit for the contents here go to refactoring.guru
Cormen, Leiserson, Rivest & Stein's Introduction to Algorithms (MIT Press, 3rd ed., 2009): book notes, with worked solutions to all 1114 exercises and problems.