Count words with the entry API in Rust
Rust interview exercise on Vectors & Slices, 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 word_counts(text) that returns how many times each whitespace-separated word appears, comparing case-insensitively (keys are lower-case). Return a BTreeMap so the result has a stable order.
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.