← Virtu Financial Interview Insights
Use a stack to track opening brackets. Iterate through each character: push opening brackets, and for closing brackets, check if the stack top matches the corresponding opening bracket; if not, return false. At the end, the stack must be empty for the string to be valid.
Pro tip: Clarify edge cases upfront, such as empty strings or strings with only opening brackets, and mention that the solution runs in O(n) time and O(n) space. This shows attention to detail and efficiency.
Restate the problem: determine if each string has balanced brackets with correct nesting and matching types. Confirm input format and expected output.
Select a stack to keep track of opening brackets. Explain that a stack follows LIFO order, which naturally handles nested brackets.
Create a mapping of closing brackets to their corresponding opening brackets. For each closing bracket, check if it matches the top of the stack.
Traverse the string: push opening brackets, and for closing brackets, pop and compare. If mismatch or empty stack, return false.
After traversal, ensure the stack is empty. State time complexity O(n) and space complexity O(n) in the worst case.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.