Java大数练习

大数阶乘

题目链接：http://acm.nyist.net/JudgeOnline/problem.php?pid=28

 import java.io.*;
 import java.util.*;
 import java.math.*;
 //import java.text.*;

 public class Main {

     /**
      * @param args
      */
     public static void main(String[] args) throws Exception{
         // TODO Auto-generated method stub
         Scanner cin = new Scanner (System.in);
         PrintWriter cout = new PrintWriter(System.out);

         int n = cin.nextInt();
         BigInteger ans = BigInteger.ONE;
         for(int i=1;i<=n;i++)
             ans = ans.multiply(BigInteger.valueOf(i));
         cout.println(ans);
         cout.flush();
     }

 }

比较大小

题目链接：http://acm.nyist.net/JudgeOnline/problem.php?pid=73

 import java.io.*;
 import java.util.*;
 import java.math.*;
 import java.text.*;

 public class Main {

     /**
      * @param args
      */
     public static void main(String[] args) {
         // TODO Auto-generated method stub
         Scanner cin = new Scanner(System.in);
         while(true)
         {
             BigInteger a = cin.nextBigInteger();
             BigInteger b = cin.nextBigInteger();
             if(a.equals(BigInteger.ZERO) && b.equals(BigInteger.ZERO) )
             {
                 break;
             }
             int flag = a.compareTo(b);
             if(flag == 0)
                 System.out.println("a==b");
             else if(flag == -1)
                 System.out.println("a<b");
             else
                 System.out.println("a>b");
         }
     }

 }

大数加法

题目链接：http://acm.nyist.net/JudgeOnline/problem.php?pid=103

 import java.io.*;
 import java.util.*;
 import java.math.*;

 public class Main {

     /**
      * @param args
      */
     public static void main(String[] args) {
         // TODO Auto-generated method stub
             Scanner cin = new Scanner(System.in);
             int T = cin.nextInt();
             int cas = 1;
             for(int i=1;i<=T;i++)
             {
                 BigInteger a = cin.nextBigInteger();
                 BigInteger b = cin.nextBigInteger();
                 BigInteger ans = a.add(b);

                 System.out.println("Case "+i+":");
                 System.out.println(a+" + "+b+" = "+ans);
             }
     }

 }