package Stack_Queue;

import java.util.Deque;

import java.util.LinkedList;

public class EvaluateRPN_150 {

public int evalRPN(String[] tokens) {

Deque<Integer> stack=new LinkedList<>();

for(String token:tokens){

if(Character.isDigit(token.charAt(0))||token.charAt(0)=='-'&&token.length()>1){

stack.push(Integer.parseInt(token));

}else {

int n2=stack.pop();

int n1=stack.pop();

stack.push(eval(n1,n2,token.charAt(0)));

}

}

return stack.pop();

}

private int eval(int n1,int n2,char symbol){

switch (symbol){

case '+':return n1+n2;

case '-':return n1-n2;

case '*':return n1*n2;

default:

return n1/n2;

}

}

public static void main(String[] args) {

EvaluateRPN_150 rpn150 = new EvaluateRPN_150();

int i = rpn150.evalRPN(new String[]{"10", "6", "9", "3", "+", "-11", "*", "/", "*", "17", "+", "5", "+"});

System.out.println(i);

}

}