import java.util.Stack;

public class Parsing{
    public static void main (String...args){
        String a = "((15/(7-(1+1)))*3)-(2+(1+1))";
        Stack<String> b = prepareExpression(a);

        for  (String x : b) System.out.printf("%s ",x);

        System.out.println();
        double k = expression(b);
        System.out.println(k);
    }
    public static Stack<String> prepareExpression(String a){ // seperates operators/digits (Stack already reversed in order to evaluate left to right)
        Stack<String> result = new Stack<String>();

        String numberBuffer = "";

        for (int i = a.length()-1; i>=0;i--){
            char k = a.charAt(i);
            if (Character.isDigit(k)) numberBuffer=k+numberBuffer;// digits

            else if (k=='-' || k =='.' || k =='E'){ // possible digits
                if  (k=='-') {
                    if (i==0) numberBuffer=k+numberBuffer;
                    else if (a.charAt(i-1) =='(' || a.charAt(i-1) =='E') numberBuffer=k+numberBuffer;
                    //else if (a.charAt(i-1) ==' ') numberBuffer=k+numberBuffer; // OPTIONAL 2+ -1 ('2','+',' ','-','1') will be valid (will convert to -1)
                    else {
                        if (!numberBuffer.isEmpty()){
                            result.push(numberBuffer);
                            numberBuffer="";
                        }
                        result.push(Character.toString(k));
                    }

                }
                else if (k=='.' || k=='E') numberBuffer=k+numberBuffer;
            }

            else if  (k=='+'|| k =='*'|| k =='/'|| k =='^'|| k =='('|| k ==')') { // nondigits
                if (!numberBuffer.isEmpty()){
                    result.push(numberBuffer);
                    numberBuffer="";
                }
                result.push(Character.toString(k));
            }
            else System.out.println("Bad input");
        }
        if (!numberBuffer.isEmpty()) result.push(numberBuffer);
        return result;
    }

    public static double expression(Stack<String> a){
        double t=term(a);
        if (a.isEmpty()) return t;

        String operand = a.pop();
        if (operand.matches("\\+")){
            return t+term(a);
        }
        else if (operand.matches("-")){
            return t-term(a);
        }
        else {
            a.push(operand);
        }
        return t;
    }
    public static double term(Stack<String> a){
        double t = additionals(a);
        if (a.isEmpty()) return t;

        String operand = a.pop();

        if (operand.matches("\\*")){
            return t*additionals(a);
        }
        else if (operand.matches("/")){
            return t/additionals(a);
        }
        else {
            a.push(operand);
        }
        return t;
    }
    public static double additionals(Stack<String> a){
        double t = primary(a);
        if (a.isEmpty()) return t;

        String operand = a.pop();

        if (operand.matches("\\^")){
            return Math.pow(t,primary(a));
        } else{
            a.push(operand);
        }
        return t;
    }
    public static double primary(Stack<String> a){
        String k = a.pop();
        if (k.matches("\\(")){
            double d = expression(a);
            if (!a.pop().matches("\\)")){
                System.out.println("hi");
            }
            return d;
        }
        return Double.parseDouble(k);
    }
}