Feature: Fully optimized valid parentheses checker #6767
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Implemented an optimized valid parentheses checker (BalancedBrackets.java) that supports all bracket types: (), [], {}, and <>. The solution handles all edge cases and ensures O(n) time and O(n) space complexity using a stack.
Details:
Edge cases handled:
Empty strings (returns true)
Null input (throws IllegalArgumentException)
Odd-length strings (cannot be balanced)
Strings with non-bracket characters (returns false)
Nested and mixed brackets of any valid combination
Optimizations:
Single pass through the string (O(n) time)
Stack stores only unmatched opening brackets (O(n) space in worst case)
Immediate rejection for unmatched or invalid characters
Testing:
Verified against existing JUnit 5 test cases in BalancedBracketsTest.java
All tests for paired brackets, unbalanced strings, null inputs, and invalid characters pass successfully
Impact:
This implementation ensures that the algorithm is robust, efficient, and ready for use in any project requiring balanced bracket validation.