About this challenge
Valid Parentheses is a easy algorithms coding challenge. It tests algorithmic thinking and complexity analysis — the kind of problem-solving that shows up constantly in technical interviews. Write your solution in the editor above, run it against the test cases, and get instant feedback — free, in your browser, no sign-up.
Show a hint & approach (spoiler)
Hint: Use a stack. Push openers, pop and match on closers. Valid iff all closers match and the stack is empty at the end.
Keep practicing
Browse all coding challenges, or build intuition for the underlying concepts with the algorithm visualizers and the developer cheatsheets.