Group words by length in Java
Java interview exercise on Collections, 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 groupByLength(words) that returns a Map from word length to the words of that length, keys in ascending order (a TreeMap) and the words of each group in their original 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.