Evaluate the value of an arithmetic expression in Reverse Polish Notation.
Valid operators are +, -, *, /. Each operand may be an integer or another expression.
Some examples:
["2", "1", "+", "3", "*"] -> ((2 + 1) * 3) -> 9 ["4", "13", "5", "/", "+"] -> (4 + (13 / 5)) -> 6
1 class Solution: 2 def evalRPN(self, tokens): 3 """ 4 :type tokens: List[str] 5 :rtype: int 6 """ 7 stack = [] 8 for i in tokens: 9 if i not in [‘+‘,‘-‘,‘*‘,‘/‘]: 10 stack.append(i) 11 else: 12 v2 = int(stack.pop()) 13 v1 = int(stack.pop()) 14 if i==‘+‘: 15 stack.append(v1+v2) 16 if i==‘-‘: 17 stack.append(v1-v2) 18 if i==‘*‘: 19 stack.append(v1*v2) 20 if i==‘/‘: 21 stack.append(v1/v2) 22 return int(stack[0]) 23
