public class Solution {
/**
* @param tokens: The Reverse Polish Notation
* @return: the value
*/
public int evalRPN(String[] tokens) {
Deque<Integer> stack = new ArrayDeque<>();
String operators = "+-*/";
for (String s : tokens) {
if (operators.contains(s)) {
int num1 = stack.pop();
int num2 = stack.pop();
if (s.equals("+")) stack.push(num1 + num2);
if (s.equals("-")) stack.push(num2 - num1);
if (s.equals("*")) stack.push(num1 * num2);
if (s.equals("/")) stack.push(num2 / num1);
} else {
stack.push(Integer.parseInt(s));
}
}
return stack.pop();
}
}
