Valid Parentheses

Stackseasy

Implement `isValid(s)` that returns `true` if every opening bracket `(`, `[`, `{` in string `s` is closed by the correct closing bracket in the correct order. Example: `isValid("()[]{}")` → `true`, `isValid("(]")` → `false`.

Sample tests

Input: isValid("()")

Output: true

Input: isValid("()[]{}")

Output: true

Input: isValid("(]")

Output: false

+ 2 hidden tests run on Submit.

Hints

Common pitfalls

Forgetting to require an empty stack at the end accepts unclosed brackets.
Matching only by count ignores bracket type mismatches.

Learning resources

MDN: Array.prototype.push / pop

Approach & explanation (try first)

Push openers, pop and check the matching type on closers, and require an empty stack at the end. O(n) time and space.

⌘/Ctrl + Enter

Run your code to see results.

← Back to problems

Valid Parentheses

Stackseasy

Sample tests

Input: isValid("()")

Output: true

Input: isValid("()[]{}")

Output: true

Input: isValid("(]")

Output: false

+ 2 hidden tests run on Submit.

Hints

Common pitfalls

Forgetting to require an empty stack at the end accepts unclosed brackets.
Matching only by count ignores bracket type mismatches.

Learning resources

MDN: Array.prototype.push / pop

Approach & explanation (try first)

Push openers, pop and check the matching type on closers, and require an empty stack at the end. O(n) time and space.

⌘/Ctrl + Enter

Run your code to see results.