Poj Solution 2845

http://poj.org/problem?id=2845

 import java.util.*;  
   
 public class Main {  
   
     public static void main(String[] args) {  
         Scanner cin = new Scanner(System.in);  
           
         int pnum = Integer.valueOf(cin.nextLine()).intValue();  
           
         for(int i = 1; i <= pnum; i++)  
         {  
             String[] str = cin.nextLine().split(" ");  
             String a = removePreZero(str[0]);  
             String b = removePreZero(str[1]);  
               
             a = reverse(a);  
             b = reverse(b);  
               
             String result = addBinary(a, b);  
             result = reverse(result);  
             result = removePreZero(result);  
             System.out.println(i + " " + result);  
         }  
   
     }  
       
     private static String addBinary(String a, String b)  
     {  
         StringBuffer sb = new StringBuffer();  
         int loa = a.length();  
         int lob = b.length();  
           
         String newa = a;  
         String newb = b;  
         if(loa > lob)  
         {  
             newa += "0";  
             for(int i = 0; i <= (loa-lob);i++)  
                 newb += "0";  
         }else if(loa == lob)  
         {  
             newa += "0";  
             newb += "0";  
         }else  
         {  
             newb += "0";  
             for(int i = 0; i <= (lob-loa);i++)  
                 newa += "0";  
         }  
           
         int carry = 0;  
       
         for(int i = 0; i < newa.length(); i++)  
         {  
             char c1 = newa.charAt(i);  
             char c2 = newb.charAt(i);  
             int tmp = c1 + c2 - 96 + carry;  
             if(tmp == 0)  
             {  
                 sb.append('0');  
                 carry = 0;  
             }else if(tmp == 1)  
             {  
                 sb.append('1');  
                 carry = 0;  
             }else if(tmp == 2)  
             {  
                 sb.append('0');  
                 carry = 1;  
             }else  
             {  
                 sb.append('1');  
                 carry = 1;  
             }  
         }  
           
         return sb.toString();  
     }  
       
     private static String reverse(String str)  
     {  
         StringBuffer sb = new StringBuffer();  
           
         for(int i = str.length() - 1; i >= 0; i--)  
         {  
             sb.append(str.charAt(i));  
         }  
           
         return sb.toString();  
           
     }  
       
     private static String removePreZero(String str)  
     {  
         int index = 0;  
           
         while(index < str.length())  
         {  
             if(str.charAt(index) == '0')  
                 index++;  
             else  
                 break;  
         }  
           
         if(index == str.length())  
             return "0";  
           
         return str.substring(index);  
     } 
}