Determine if a string has valid parentheses. Only parentheses characters are considered: '(' and ')'. Other characters are ignored. An empty string is valid. Return null for null input.
Examples:
Input: s = "()"
Output: true
Explanation: Opening and closing parentheses are balanced
Input: s = "())("
Output: false
Explanation: Closing appears before matching opening
Apex Code Editor
Welcome to Lightning Challenge!
How It Works
- • Write your solution in the code editor
- • Connect your Salesforce org to test
- • Submit to check if your solution passes
- • Use hints if you get stuck
Contest Alert
🏆 #CodeEveryDay July 2026
Contest runs July 1 - 31. Complete challenges to climb the leaderboard!
Only the 31 daily challenges shown during this contest count toward points. Earlier dailies don't carry over.