Diff two dicts in Python
Python 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 diff_keys(before, after) that returns {"added": [...], "removed": [...], "changed": [...]}: keys only in after, keys only in before, and keys in both whose value differs. Each list is sorted.
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.