题解 | 逆波兰表达式求值

import re
from re import A
#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param tokens string字符串一维数组 
# @return int整型
#
class Solution:
    def evalRPN(self , tokens: List[str]) -> int:
        # write code here
        stack = []
        for token in tokens:
            if token in "+-*/":
                a = stack.pop()
                b = stack.pop()
                if token == "+":
                    stack.append(a + b)
                elif token == "-":
                    stack.append(b - a)
                elif token == "*":
                    stack.append(a * b)
                else:
                    stack.append(int(b / a))
            else:
                stack.append(int(token))
        return stack[0]