Solution: Basic Calculator

Statement

Given a string containing an arithmetic expression, implement a basic calculator that evaluates the expression string. The expression string can contain integer numeric values and should be able to handle the “+” and “-” operators, as well as “()” parentheses.

Constraints:

Let s be the expression string. We can assume the following constraints:

• $1 \leq$ s.length $\leq 3 \times 10^{3}$