Evaluate_Reverse_Polish_Notation.py

# Runtime = 50ms (80.28%) 
# Memory = 15.6MB (38.57%)

class Solution(object):
    def evalRPN(self, tokens):
        stack = []
        for t in tokens:
            if t not in "+-*/":
                stack.append(int(t))
            else:
                r, l = stack.pop(), stack.pop()
                if t == "+":
                    stack.append(l+r)
                elif t == "-":
                    stack.append(l-r)
                elif t == "*":
                    stack.append(l*r)
                else:
                    stack.append(int(float(l)/r))
        return stack.pop()