class Solution {
public int evalRPN(String[] tokens) {
Deque[HTML_REMOVED] stack = new LinkedList[HTML_REMOVED]();
int n = tokens.length;
for (int i = 0; i < n; i++) {
String token = tokens[i];
if (isNumber(token)) {
stack.push(Integer.parseInt(token));
} else {
int num2 = stack.pop();
int num1 = stack.pop();
switch (token) {
case “+”:
stack.push(num1 + num2);
break;
case “-“:
stack.push(num1 - num2);
break;
case “*”:
stack.push(num1 * num2);
break;
case “/”:
stack.push(num1 / num2);
break;
default:
}
}
}
return stack.pop();
}

public boolean isNumber(String token) {
    return !("+".equals(token) || "-".equals(token) || "*".equals(token) || "/".equals(token));
}

}