51nod 1005 1027 1029 高精度

Java大数用法参考：https://www.cnblogs.com/jin-nuo/p/5313205.html

1005 大数加法：

import java.util.*;
import java.io.*;
import java.math.*;
public class Main{
    public static void main(String[] args) {
        Scanner cin=new Scanner(System.in);
        BigInteger a=cin.nextBigInteger();
        BigInteger b=cin.nextBigInteger();
        System.out.println(a.add(b));
    }

}

1027 大数乘法：

import java.util.*;
import java.io.*;
import java.math.*;
public class Main{
    public static void main(String[] args) {
        Scanner cin=new Scanner(System.in);
        BigInteger a=cin.nextBigInteger();
        BigInteger b=cin.nextBigInteger();
        System.out.println(a.multiply(b));
    }

}

1029 大数除法 取模：

import java.util.*;
import java.io.*;
import java.math.*;
public class Main{
    public static void main(String[] args) {
        Scanner cin=new Scanner(System.in);
        BigInteger a=cin.nextBigInteger();
        BigInteger b=cin.nextBigInteger();
        System.out.println(a.divide(b));
        System.out.println(a.remainder(b));
    }

}

牛客小白月赛12 B 求A^B mod P

题目链接：https://ac.nowcoder.com/acm/contest/392/B

import java.util.*;
import java.io.*;
import java.math.*;
 
public class Main{
    public static void main(String[] args){
        Scanner cin=new Scanner(System.in);
        int T=cin.nextInt();
        while(T>0){
            T--;
            BigInteger a=cin.nextBigInteger();
            BigInteger b=cin.nextBigInteger();
            BigInteger p=cin.nextBigInteger();
            BigInteger res=BigInteger.valueOf(1);
            while(b.compareTo(BigInteger.valueOf(0))!=0){
                if(b.mod(BigInteger.valueOf(2)).compareTo(BigInteger.valueOf(1))==0)
                    res=res.multiply(a).mod(p);
                a=a.multiply(a).mod(p);
                b=b.divide(BigInteger.valueOf(2));
            }
            System.out.println(res);
        }
    }
}