I knew this problem category but still fumbled the operator precedence part for a minute.
Clarify that the expression is a valid infix expression with no parentheses and that division is integer division truncating toward zero. Then propose a two-pass approach: first tokenize the string, then evaluate using a stack to handle operator precedence, or use a single pass with a stack for numbers and a variable for the last operator.
Pro tip: Mention that you can solve it in one pass without a stack by keeping track of the last operator and using a running result, but using a stack is simpler and less error-prone. Also, explicitly state how you handle division by zero and integer division truncation.
Ask about parentheses, unary operators, division behavior (integer vs float), and whether the expression is always valid. Confirm that only non-negative integers and the four operators are present.
Decide between a stack-based approach for operator precedence or a two-pass method (first handle * and /, then + and -). Explain the trade-offs in time and space complexity.
Iterate through the string, building multi-digit numbers and applying operators. Use a stack to store intermediate results, handling * and / immediately and deferring + and -.
Test with expressions containing spaces, multiple digits, division truncation, and division by zero (if allowed). Walk through a few examples to verify correctness.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.