← Bloomberg Interview Insights
Start by clarifying the problem constraints (e.g., array size, distinct integers) and then present a backtracking solution that builds subsets incrementally. Explain the decision at each element (include or exclude) and analyze the time and space complexity.
Pro tip: Mention that the total number of subsets is 2^n, so any algorithm must take at least O(2^n) time; this shows you understand the inherent complexity and sets realistic expectations.
Ask about input size, whether the array can be empty, and if the order of subsets matters. Confirm that the integers are distinct.
Decide between backtracking, bit manipulation, or iterative expansion. Backtracking is intuitive and easy to explain; bit manipulation is concise but less flexible.
Walk through the chosen approach step-by-step, using a small example to illustrate how subsets are generated.
State that time complexity is O(n * 2^n) and space complexity is O(n * 2^n) for the output, plus O(n) for recursion stack.
Compare approaches, mention handling of empty input, and note that the solution naturally handles duplicates if they were present (with sorting and skipping).
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.
Looked easy and I almost said so out loud, which would've been embarrassing.
Clarify that only parentheses matter and other characters can be ignored. Use a stack to track opening brackets, ensuring each closing bracket matches the most recent unmatched opening. After processing, verify the stack is empty.
Pro tip: Mention that you can optimize space by using a counter if only one type of parenthesis is present, but a stack is necessary for multiple types. Also, discuss edge cases like empty string or strings with no parentheses.
Confirm that the string may contain other characters, but only parentheses need to be validated. Ask if there are multiple types of parentheses (e.g., (), [], {}) or just one.
For multiple types, use a stack to track opening brackets. For a single type, a simple counter suffices. Explain the trade-offs.
Traverse the string. On an opening bracket, push onto the stack (or increment counter). On a closing bracket, check if it matches the top of the stack (or if counter > 0) and pop (or decrement). If mismatch or empty stack, return false.
After traversal, ensure the stack is empty (or counter is zero). If not, return false; otherwise, return true.
State that time complexity is O(n) and space complexity is O(n) in the worst case (or O(1) for single type with counter).
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.