Basic Calculator

Try to solve the Basic Calculator problem.


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.


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

  • 11 \leq s.length 3×103\leq 3 \times 10^{3}
  • s consists of digits, “+”, “-”, “(”, and “)”.
  • s represents a valid expression.
  • “+” is not used as a unary operation ( +1+1 and +(2+3)+(2 + 3) are invalid).
  • “-” could be used as a unary operation (1-1 and (2+3)-(2 + 3) are valid).
  • There will be no two consecutive operators in the input.
  • Every number and running calculation will fit in a signed 32-bit integer.


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