Use a stack-based approach to handle nested parentheses and operator precedence. Iterate through the expression, maintaining a current result and sign, and push the current result and sign onto a stack when encountering '('. When encountering ')', pop and combine. This elegantly handles nested parentheses without explicit recursion.
Pro tip: Clarify constraints upfront (e.g., integer division truncation, spaces, unary operators) and mention that you'll handle edge cases like division by zero or empty input. This shows attention to detail and prevents misunderstandings.
Ask about integer vs floating-point division, handling of spaces, unary operators, and invalid expressions. Confirm the expected output format.
Decide between stack-based iterative approach or recursive descent parser. For LeetCode 772, a stack is simpler and avoids recursion depth issues.
Iterate through characters, maintaining current number, result, and sign. On '(', push current result and sign, reset them. On ')', pop and combine. Apply operators with precedence.
Walk through examples like '1+2*3', '(1+(4+5+2)-3)+(6+8)', and edge cases like negative numbers, division truncation, and nested parentheses.
State time and space complexity (O(n) time, O(n) space for stack). Mention potential optimizations or alternative approaches like recursive descent.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.