Use a stack to track opening brackets and validate closing brackets in order. Iterate through the string, pushing opening brackets and popping when a matching closing bracket is encountered. At the end, the stack should be empty for a valid string.
Pro tip: Clarify the bracket types (e.g., (), [], {}) and whether the string can contain non-bracket characters. Also, discuss edge cases like empty string and single bracket, and mention time/space complexity upfront.
Ask if only bracket characters are allowed and which types. Confirm edge cases: empty string, single bracket, nested and interleaved brackets.
Select a stack (LIFO) because brackets must be closed in reverse order of opening. Explain why a queue or other structure wouldn't work.
Iterate through each character: if opening bracket, push onto stack; if closing bracket, check if stack is empty or top doesn't match, return false; otherwise pop. After loop, return true only if stack is empty.
State time complexity O(n) and space O(n) in worst case. Walk through examples like '()[]{}', '([)]', and '(((' to validate.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.