Cfrtjryk

I am trying to solve a programming challange that involves converting reverse polish notation to infix notation. For example: 1 3 + 2 4 5 - + / would be: ((1+3)/(2+(4-5))) My solution so far does work, but it's not fast enough. So I am looking for any optimization advice.

public class betteralgo {

    public static void main(String args) throws IOException {

        BufferedReader bi = new BufferedReader(new 

        InputStreamReader(System.in));

        String line = bi.readLine();

        String input = line.split(" ");

        StringBuilder builder = new StringBuilder();

        Stack<String> stack = new Stack<String>();



        for(String e:input) {

            switch(e){

                case("+"):

                case("-"):

                case("*"):

                case("/"):

                    String i = stack.pop();

                    String k = stack.pop();

                    stack.push("(" + k + e + i + ")");

                break;

                default:

                    stack.push(e);

                }

            }

        System.out.println(stack.pop());        

       }       

    }

If you want to do it faster I know that I once solved this with a hashMap which is much faster. The problem is that, depending on what you are going to use it for, it's harder to implement. I don't have time to show exactly how I did it now, I might come back to you, but it should give you a pointer on where to look.