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Solution: Basic Calculator II

Explore how to evaluate a string mathematical expression containing non-negative integers and operators by using a stack-based approach. Understand the processing of addition, subtraction, multiplication, and division with correct operator precedence. Practice implementing this efficient solution in C++ without relying on built-in evaluation functions.

Statement

Given a string s representing a mathematical expression containing non-negative integers and the operators +, -, *, and /, evaluate the expression and return its result.

Integer division must truncate toward zero. You may assume the expression is always valid, and all intermediate results fall within the 3232-bit signed integer range.

Note: Using any built-in function that directly evaluates strings as mathematical expressions (e.g., eval()) is not allowed.

Constraints:

  • 11 \leq s.length 3×105\leq 3 \times 10^5 ...