150. Evaluate Reverse Polish Notation - LeetCode Solution

class Solution:
    def evalRPN(self, tokens: List[str]) -> int:
        stack = []


        for i in tokens:
            if i not in "/*+-":
                stack.append(i)
            else:
                a = int(stack.pop())
                b = int(stack.pop())
                if i == "+":
                    stack.append(a+b)
                elif i == "*":
                    stack.append(int(a*b))
                elif i=="/":
                    stack.append(int(b/a))
                else:
                    stack.append(b-a)


        return stack[0]