1221 : 후위표기법1

import java.util.Scanner;
 
public class Main {
 
    static int stack[] = new int[100];
    static int pos = 0;
     
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner scan = new Scanner(System.in);
 
        int m;
        char arr[] = new char[101];
        int i, j;
         
        m = scan.nextInt();
         
        for (i = 0; i < m; i++) {
            arr[i] = scan.next().charAt(0);
             
            if (Character.isDigit(arr[i])) {
                push(arr[i]-'0');
            }
            else {
                int a = pop();
                int b = pop();
                 
                if (arr[i] == '+') {
                    push(a + b);
                }
                if (arr[i] == '-') {
                    push(b - a);
                }
                if (arr[i] == '*') {
                    push(a * b);
                }
                if (arr[i] == '/') {
                    push(b / a);
                }
     
            }
        }
        System.out.print(pop());
    }
     
    public static void push(int a) {
        stack[pos++] = a;
    }
    public static int pop() {
        return stack[--pos];
         
    }
    public static boolean isEmpty() {
        return pos == 0;
    }
 
}

http://www.jungol.co.kr/bbs/board.php?bo_table=pbank&wr_id=504&sca=2070