Leetcode-evaluate Reverse Polish Notation (Python)

Problem

Evaluate the value of an arithmetic expression in Reverse Polish Notation.

Valid operators is+,-,*,/. Each operand is an integer or another expression.

Some Examples:

  ["2", "1", "+", "3", "*")--((2 + 1) (3)-9  ["4", "", "5", "/", "+"], 4 + (13/5))

Code

Class solution:    # @param tokens, a list of string    # @return An integer    def evalrpn (self, Tokens):        stack = []        for item in tokens:            if Item isn't in ("+", "-", "*", "/"):                stack.append (int (item))            else:                op2 = stack. Pop ()                OP1 = Stack.pop ()                If Item = = "+":                    stack.append (OP1 + op2)                elif Item = = "-":                    Stack.append ( OP1-OP2)                elif Item = = "*":                    stack.append (OP1 * op2)                elif Item = = "/":                    stack.append (int (OP1 *1.0/OP2 ))        return stack[0]

Leetcode-evaluate Reverse Polish Notation (Python)