Implement a function to solve an string given in reverse polish notation.

Question

DigitalFox · Accepted Answer

import java.util.StringTokenizer;
import java.util.Stack;
class Test{
	public static void main(String arg[]) {
		String pf = "3 0 /  ";
		StringTokenizer pfa = new StringTokenizer(pf," ");
		Stack st = new Stack();
		String input="";
		Double result = 0.0;
		while(pfa.hasMoreElements()){
			try{
				input = pfa.nextElement().toString();
				Double num = Double.parseDouble(input);				
				st.push(num);				
			} catch(Exception e) {				
				try{
					Double num1 = st.pop();
					Double num2 = st.pop();
					if(input.equals("+")) { result = num2+num1;}
					else if(input.equals("-")) {result = num2-num1;}
					else if(input.equals("/")) {if(num1==0.0){throw new ArithmeticException();} else{result = num2/num1;}}
					else if(input.equals("*")) {result = num2*num1;}
					else {System.out.println("Not a valid input"); break;}
					st.push(result);
					continue;
				}catch(Exception ex){
					System.out.println("Please check your input expression.");
				}
			}
		}
		System.out.println("The result : "+result);
	}
}

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