【HDOJ】2424 Gary's Calculator

大数乘法加法，直接java A了。

 import java.util.Scanner;
 import java.math.BigInteger;

 public class Main {
     public static void main(String[] args) {
         Scanner cin = new Scanner(System.in);
         int n;
         int i, j, k, tmp;
         int top;
         boolean flag;
         int t = ;
         while (cin.hasNext()) {
             n = cin.nextInt();
             for (i=; i<n; ++i)
                 buf[i] = cin.next();
             flag = true;
             if ((n&) == )
                 flag = false;
             for (i=; flag&&i<n; ++i) {
                 if ((i & ) == ) {
                     if (buf[i].charAt()!='+' && buf[i].charAt()!='*')
                         flag = false;
                 } else {
                     if (buf[i].charAt()=='+' || buf[i].charAt()=='*')
                         flag = false;
                 }
             }
             System.out.printf("Case %d: ", ++t);
             if (flag==false || n==) {
                 System.out.println("Invalid Expression!");
                 continue;
             }
             top = ;
             bi[top++] = new BigInteger(buf[]);
             i = ;
             while (i < n) {
                 if (buf[i].charAt() == '*') {
                     BigInteger a = bi[top-];
                     BigInteger b = new BigInteger(buf[i+]);
                     bi[top-] = a.multiply(b);
                 } else {
                     bi[top++] = new BigInteger(buf[i+]);
                 }
                 i += ;
             }
             BigInteger sum = BigInteger.ZERO;
             for (i=; i<top; ++i) {
                 sum = sum.add(bi[i]);
             }
             System.out.println(sum.toString());
         }
     }

     final public static int MAXN = ;
     public static String[] buf = new String[MAXN];
     public static BigInteger[] bi = new BigInteger[MAXN];
 }