题目：
表达式计算II
Write a program that reads an expression in a line as input and prints out the result. Only integers and operators below are allowed in the expression:
( )+ - * / %
输入格式:
A line of expression.
输出格式:
The result.
输入样例:
(2+32)/2-6
输出样例:
11

import java.util.Scanner;
import java.util.Stack;



public class Hello {

	   public static void main(String[] args) {
           Scanner scanner = new Scanner(System.in);
           String str = scanner.nextLine();
           //double result1 = compute("-3*-3");
            double result1 = compute(str);
           System.out.println((int) result1);
   }

   public static int priority(char s) {
           switch (s) {
           case '(':
           case ')':
                   return 0;
           case '-':
           case '+':
                   return 1;
           case '*':
           case '%':
           case '/':
                   return 2;
           default:
                   return -1;

           }
   }

   public static double compute(double num1, double num2, char s) {
           switch (s) {
           case '(':
           case ')':
                   return 0;
           case '-':
                   return num1 - num2;
           case '+':
                   return num1 + num2;
           case '%':
                   return num1 % num2;
           case '*':
                   return num1 * num2;
           case '/':
                   return num1 / num2;
           default:
                   return 0;

           }
   }

   public static double compute(String str) {
           double num[] = new double[20];
           int flag = 0, begin = 0, end = 0, now;
           now = -1;
           Stack<Character> st = new Stack<Character>();
           for (int i = 0; i < str.length(); i++) {
                   char s = str.charAt(i);
                   if (s == ' ') {

                   } else if (s == '+' || s == '-' || s == '*' || s == '/' || s == '(' || s == ')' || s == '%') {
                           if (flag == 1) {
                                   now += 1;
                                   if (end < begin) {
                                           num[now] = Integer.valueOf(str.substring(begin, begin + 1));
                                   } else {
                                           num[now] = Integer.valueOf(str.substring(begin, end + 1));
                                   }
                                   // System.out.println(num[now]);
                                   flag = 0;
                           }
                           if (s == '-') {
                                   if (i == 0) {
                                           flag = 1;
                                           begin = 0;
                                   } else if (str.charAt(i - 1) == '(' || str.charAt(i - 1) == '*'
                                                   || str.charAt(i - 1) == '/') {
                                           flag = 1;
                                           begin = i;
                                   }
                                   else {
                                	   if (st.empty()) {
                                           st.push(s);
                                   } else if (s == ')') {
                                           num[now - 1] = compute(num[now - 1], num[now], st.pop());
                                           now -= 1;
                                           st.pop();
                                   } else if (s == '(') {
                                           st.push(s);
                                   } else if (priority(s) <= priority(st.peek())) {
                                           num[now - 1] = compute(num[now - 1], num[now], st.pop());
                                           now -= 1;
                                           st.push(s);
                                   } else {
                                           st.push(s);
                                   }
                                   }
                           } else if (st.empty()) {
                                   st.push(s);
                           } else if (s == ')') {
                                   num[now - 1] = compute(num[now - 1], num[now], st.pop());
                                   now -= 1;
                                   st.pop();
                           } else if (s == '(') {
                                   st.push(s);
                           } else if (priority(s) <= priority(st.peek())) {
                                   num[now - 1] = compute(num[now - 1], num[now], st.pop());
                                   now -= 1;
                                   st.push(s);
                           } else {
                                   st.push(s);
                           }

                   } else if (flag == 0) {
                           flag = 1;
                           begin = i;
                   } else {
                           end = i;
                   }

           }
           if (flag == 1) {
                   now += 1;
                   if (end < begin) {
                           num[now] = Integer.valueOf(str.substring(begin, begin + 1));
                   } else {
                           num[now] = Integer.valueOf(str.substring(begin, end + 1));
                   }
                   // System.out.println(num[now]);
           }
           while (now > 0) {
                   num[now - 1] = compute(num[now - 1], num[now], st.pop());
                   now -= 1;
           }
           return num[0];
   }

}