#150

Evaluate Reverse Polish Notation

medium· Stackruns: 0

You are given an array of strings tokens that represents an arithmetic expression in Reverse Polish Notation. Evaluate the expression and return the result. The valid operators are '+', '-', '*', and '/'. Division between two integers truncates toward zero.

wpm 0acc 100%time 0:000 / 596

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)
                else:
                    stack.append(int(a / b))
            else:
                stack.append(int(token))
        return stack[0]

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