Evaluate Reverse Polish Notation

Problem

Evaluate an arithmetic expression given in reverse Polish notation, where tokens are integers or the operators +, -, * and /.

Push numbers onto a stack and, for each operator, pop the two most recent values, apply the operation and push the result. Division truncates toward zero; the input is always a valid expression.

Hint

For division, compute with absolute values and then reapply the sign to truncate toward zero.

Test cases

case 1

in: [["2","1","+","3","*"]]

expected: 9

case 2

in: [["4","13","5","/","+"]]

expected: 6

case 3

in: [["10","6","9","3","+","-11","*","/","*","17","+","5","+"]]

expected: 22

case 4

in: [["3"]]

expected: 3

case 5

in: [["7","-2","/"]]

expected: -3

Starter codePython

def eval_rpn(tokens):
    # Your code here
    pass

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