Basic Calculator

Problem

Evaluate a string arithmetic expression containing non-negative integers, the operators +, -, * and /, and spaces, without parentheses.

Track the previous operator and a stack: numbers are pushed, negated or combined with the top of the stack for multiplication and division. Division truncates toward zero.

Hint

Appending a sentinel plus sign forces the final number to be processed.

Test cases

case 1

in: ["3+2*2"]

expected: 7

case 2

in: [" 3/2 "]

expected: 1

case 3

in: [" 3+5 / 2 "]

expected: 5

case 4

in: ["14-3/2"]

expected: 13

case 5

in: ["1+1"]

expected: 2

Starter codePython

def basic_calculator(s):
    # Your code here
    pass

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