My brain went to this loop where you just keep stripping adjacent matching pairs until nothing's left or you're stuck.
Use a stack to track opening brackets, pushing each opening bracket and popping when a closing bracket is encountered to check for a match. Iterate through the string, and at the end, ensure the stack is empty to confirm all brackets are properly closed.
Pro tip: Clarify edge cases upfront (empty string, non-bracket characters) and discuss time/space complexity (O(n) time, O(n) space) to demonstrate thoroughness. Also, mention that this is a common interview question and you can optimize space by using a counter for a single bracket type, but a stack is needed for multiple types.
Restate the problem to ensure clarity: check if brackets are properly nested and matched. Ask about input constraints (e.g., string length, allowed characters) and expected return type.
Explain that a stack is ideal because brackets follow LIFO order. Mention that a hash map can map closing brackets to opening brackets for quick lookup.
Describe iterating 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 if stack is empty.
Discuss empty string (return true), string with only opening brackets (return false), and strings with non-bracket characters (ignore or handle as per requirement).
State time complexity O(n) and space O(n) in worst case. Walk through a few examples (e.g., '()[]{}', '([)]', '{[]}') to verify correctness.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.