Merge with defaults in C#
C# interview exercise on Dictionaries & Sets, difficulty 2 of 3. Solve it in the editor beside a worked example; the tests run the moment you do.
Write WithDefaults(defaults, options) that returns a new dictionary: every default, overridden by options, except that an option whose value is null does not override. Neither input may change.
Each exercise pairs a worked example with a twin problem to solve in a real editor; the tests run the moment you do. Progress is saved in your browser, and in your account if you sign in.