Balanced brackets 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 isBalanced(s) that returns true when every opening bracket in s ( [ { has its matching closer in the right order. Other characters are ignored. Use a Deque<Character> as a stack: push openers, and on a closer check that the top is its partner.
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.