Basic Calculator I

Problem

Evaluate a basic arithmetic expression containing +, -, parentheses, and spaces.

Digits form multi-digit numbers, and a sign before a parenthesis applies to the whole group. Keep a current result, a pending sign, and a stack of outer results and signs. Subtraction is handled by adding the negated value.

Return the integer value of the expression.

Hint

On an opening parenthesis push the result so far and the current sign, then start fresh.

Test cases

case 1

in: ["1 + 1"]

expected: 2

case 2

in: [" 2-1 + 2 "]

expected: 3

case 3

in: ["(1+(4+5+2)-3)+(6+8)"]

expected: 23

case 4

in: ["-2+ 1"]

expected: -1

case 5

in: ["0"]

expected: 0

Starter codePython

def basic_calculator(s):
    # Your code here
    pass

5 test cases · run your code against them in the editor