LC-0150 Medium LeetCode

150. Evaluate Reverse Polish Notation

Array Math Stack

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Difficulty: medium Acceptance: 55% Topics: Array, Math, Stack

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Reading material

Arrays & Hashing 12 min Math & Geometry 12 min Stacks & Queues 11 min

Reference solution (spoiler · python)

class Solution:
    def evalRPN(self, tokens: List[str]) -> int:
        stack = []

        for token in tokens:
            if token.isdigit() or (token[0] == "-" and token[1:].isdigit()):
                stack.append(int(token))
            else:
                num2 = stack.pop()
                num1 = stack.pop()
                if token == "+":
                    stack.append(num1 + num2)
                elif token == "-":
                    stack.append(num1 - num2)
                elif token == "*":
                    stack.append(num1 * num2)
                elif token == "/":
                    stack.append(int(num1 / num2))

        return stack[0]

Solution from kamyu104/LeetCode-Solutions · MIT