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  1. 1. 150. Evaluate Reverse Polish Notation

150. Evaluate Reverse Polish Notation

  • Stack, Reverse Polish Notation
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class Solution(object):
    def evalRPN(self, tokens):
        stack = []
        for token in tokens:
            if token in "+-*/":
                n2 = stack.pop()
                n1 = stack.pop()
                if token == '+':
                    temp = n1 + n2
                elif token == '-':
                    temp = n1 - n2
                elif token == '*':
                    temp = n1 * n2
                else:
                    temp = n1 / n2
                    if n1 * n2 < 0 and n1 % n2 != 0:
                        temp += 1
                stack.append(temp)
            else:
                stack.append(int(token))
        return stack.pop()
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