在Python中挑战Kattis波兰语符号

def evaluate_polish_notation(expression):
    stack = []
    operators = ['+', '-', '*', '/']

    for element in expression.split():
        if element.isdigit():
            stack.append(int(element))
        elif element in operators:
            operand2 = stack.pop()
            operand1 = stack.pop()

            if element == '+':
                result = operand1 + operand2
            elif element == '-':
                result = operand1 - operand2
            elif element == '*':
                result = operand1 * operand2
            elif element == '/':
                result = operand1 / operand2

            stack.append(result)

    return stack[0]

expression = "+ 2 3"
result = evaluate_polish_notation(expression)
print(result)  # 输出结果为 5