HDU P2106 JAVA

Problem Description
As we know , we always use the decimal system in our common life, even using the computer. If we want to calculate the value that 3 plus 9, we just import 3 and 9.after calculation of computer, we will get the result of 12.
But after learning <>,we know that the computer will do the calculation as the following steps:
1 computer change the 3 into binary formality like 11;
2 computer change the 9 into binary formality like 1001;
3 computer plus the two number and get the result 1100;
4 computer change the result into decimal formality like 12;
5 computer export the result;

In the computer system there are other formalities to deal with the number such as hexadecimal. Now I will give several number with a kind of change method, for example, if I give you 1011(2), it means 1011 is a number in the binary system, and 123(10) means 123 if a number in the decimal system. Now I will give you some numbers with any kind of system, you guys should tell me the sum of the number in the decimal system.

Input
There will be several cases. The first line of each case contains one integers N, and N means there will be N numbers to import, then there will be N numbers at the next N lines, each line contains a number with such form : X1….Xn.(Y), and 0<=Xi

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()){
            int t = sc.nextInt();
            int sum=0;
            for(int i=0;i<t;i++){
                String str = sc.next();
                sum+=toTen(str);
            }
            System.out.println(sum);
        }

    }

    private static int toTen(String str) {
        char a [] = str.toCharArray();
        String str1 = "";
        int m=0;
        // str1 表示  数，str2 表示 几进制
        int x =0;
        for(int i=0;i<a.length;i++){
                if(a[i]=='('){
                    x=i;
                    break;
                }
                str1=str1+a[i];
        }
        if(a[x+2]!=')'){
            m=10;
        }else{
            m=(int)a[x+1]-48;
        }
        double sum = zhuanhua(str1,m,10);
        return (int)sum;
    }
    private static double zhuanhua(String str1, int x, int y) {
        double sum=0;
        char a [] = str1.toCharArray();
        for(int i=0;i<a.length;i++){
            sum=sum+Mi((int)a[i]-48,x,a.length-1-i);
        }
        return sum;
    }
    private static double Mi(int x, int y, int k) {
        for(int i=0;i<k;i++){
            x=x*y;
        }
        return x;
    }

}