Flatten a recursive enum in Rust
Rust interview exercise on Vectors & Slices, difficulty 3 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.
Rust has no arbitrarily nested arrays, so nesting is modelled with a recursive enum. Write flatten(value) that returns every Int inside a Nested value, depth-first, left to right.
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.