Java大数

转自：https://www.cnblogs.com/zufezzt/p/4794271.html

import java.util.*;
import java.math.*;
public class Main{
    public static void main(String args[]){
       Scanner cin = new Scanner(System.in);
       BigInteger a, b;
      
       //以文件EOF结束
       while (cin.hasNext()){
           a = cin.nextBigInteger();
           b = cin.nextBigInteger();
          
           System.out.println(a.add(b)); //大整数加法
           System.out.println(a.subtract(b)); //大整数减法
           System.out.println(a.multiply(b)); //大整数乘法
           System.out.println(a.divide(b)); //大整数除法(取整)
           System.out.println(a.remainder(b)); //大整数取模
          
           //大整数的比较
           if( a.compareTo(b) == 0 ) System.out.println("a == b"); //大整数a==b
           else if( a.compareTo(b) > 0 ) System.out.println("a > b"); //大整数a>b
           else if( a.compareTo(b) < 0 ) System.out.println("a < b"); //大整数a<b
          
           //大整数绝对值
           System.out.println(a.abs()); //大整数a的绝对值
          
           //大整数的幂
           int exponent=10;
           System.out.println(a.pow(exponent)); //大整数a的exponent次幂
          
           //返回大整数十进制的字符串表示
           System.out.println(a.toString());
          
           //返回大整数p进制的字符串表示
           int p=8;
           System.out.println(a.toString(p));
       }
    }
}

转自：https://blog.csdn.net/morejarphone/article/details/51884888

HDU 1002

a+b大数版

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

public class Main {
    void solve () {
        BigInteger a, b, c;
        Scanner cin = new Scanner(System.in);
        int t = cin.nextInt ();
        for (int i = 1; i <= t; i++) {
            System.out.println ("Case " + i + ":");
            a = cin.nextBigInteger ();
            b = cin.nextBigInteger ();
            System.out.println (a + " + " + b + " = " + a.add (b));
            if (i != t) System.out.println ();
        }
    }
    public static void main (String[] args) {
        Main work = new Main();
        work.solve ();
    }
}

HDU 1042

阶乘大数版

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

public class Main {
    int maxn = 10005;
    void solve () {
        Scanner cin = new Scanner(System.in);
        int n;
        while (cin.hasNext()) {
            n = cin.nextInt ();
            BigInteger ans = BigInteger.valueOf (1);
            for (int i = 2; i <= n; i++) {
                ans = ans.multiply (BigInteger.valueOf (i));
            }
            System.out.println (ans);
        }
    }
    public static void main (String[] args) {
        Main work = new Main();
        work.solve ();
    }
}

HDU 1297

f(n)=f(n−1)+f(n−2)+f(n−4)f(n)=f(n−1)+f(n−2)+f(n−4)

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

public class Main {
    void solve () {
        Scanner cin = new Scanner(System.in);
        BigInteger[] ans = new BigInteger[1001];
        ans[1] = BigInteger.valueOf (1);
        ans[2] = BigInteger.valueOf (2);
        ans[3] = BigInteger.valueOf (4);
        ans[4] = BigInteger.valueOf (7);
        for (int i = 5; i <= 1000; i++) {
            ans[i] = ans[i-1].add (ans[i-2].add (ans[i-4]));
        }
        while (cin.hasNext ()) {
            int n = cin.nextInt ();
            System.out.println (ans[n]);
        }
    }
    public static void main (String[] args) {
        Main work = new Main();
        work.solve ();
    }
}

HDU 1753

高精度小数A+B，要去掉末尾的后导0.

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

public class Main {
    void solve () {
        //BigInteger a, b, c;
        Scanner cin = new Scanner(System.in);
        BigDecimal a = BigDecimal.valueOf (0);
        BigDecimal b = BigDecimal.valueOf (0);
        while (cin.hasNext ()) {
            a = cin.nextBigDecimal ();
            b = cin.nextBigDecimal ();
            System.out.println (a.add (b).stripTrailingZeros().toPlainString());
        }
    }
    public static void main (String[] args) {
        Main work = new Main();
        work.solve ();
    }
}