Reverse Polish calculator

In reverse Polish notation the operator comes after its two numbers: 3 4 + is 7 and 5 1 2 + 4 * + 3 - is 14.

Write evaluate(tokens) for a list of strings — whole numbers and +, -, * — returning the number.

def evaluate(tokens):
    stack = []
    for t in tokens:
        stack.append(int(t))
    return stack[-1]

Run adds print(evaluate(["3", "4", "+"])) after your code, to try it.

Stuck on the idea rather than the code? The Stacks and queues lesson walks through it.