Merge overlapping intervals in Java
Java interview exercise on Algorithms & recursion, 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.
Write mergeIntervals(intervals) that merges every overlapping or touching {start, end} pair and returns the result sorted by start. Sort a copy by start, then walk it: extend the last merged interval when the next one starts at or before its end, otherwise append.
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.