题解 | #逆波兰表达式求值#

from typing import List

class Solution:
    def evalRPN(self, tokens: List[str]) -> int:
        stack = []
        for token in tokens:
            if token in {'+', '-', '*', '/'}:
                b = stack.pop()
                a = stack.pop()
                if token == '+':
                    stack.append(a + b)
                elif token == '-':
                    stack.append(a - b)
                elif token == '*':
                    stack.append(a * b)
                elif token == '/':
                    # Ensure b is not zero to avoid division by zero error
                    if b == 0:
                        raise ValueError("Division by zero encountered")
                    stack.append(int(a / b))  # Assuming integer division is intended
            else:
                stack.append(int(token))
        return stack[0]  # The final result is on top of the stack