Diff two dictionaries in C#
C# interview exercise on Practical, difficulty 2 of 3. Solve it in the editor beside a worked example, or cold in Interview mode with the example hidden; the tests run the moment you do.
Write DiffKeys(before, after) that returns a tuple of three sorted lists of key names: Added (only in after), Removed (only in before) and Changed (in both, with a different value).
Each exercise pairs a worked example with a twin problem to solve in a real editor; the tests run the moment you do. Interview mode hides the example: solve it from memory, without the hint or the solution, and it counts as solved cold. Progress is saved in your browser, and in your account if you sign in.