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);
            }
    }

}