JAVA 大数类

Posted 2020-10-09

碰到很多大数类的题目，听说JAVA比较流氓，赶紧去学习一波（ <(?????)> ）

 

大数相加：

 1 //JAVA 大数相加 
 2 import java.math.BigInteger;
 3 import java.util.*;
 4 import java.io.*;
 5 
 6 public class Main
 7 {
 8     public static void main(String args[])
 9     {
10         Scanner cin = new Scanner(System.in);
11             BigInteger a = cin.nextBigInteger();
12             BigInteger b = cin.nextBigInteger();
13             BigInteger ans = a.add(b);
14             System.out.println(ans);
15     }
16 }

 

大数相乘：

 1 //JAVA 大数相乘 
 2 import java.math.BigInteger;
 3 import java.util.*;
 4 import java.io.*;
 5 
 6 public class Main
 7 {
 8     public static void main(String args[])
 9     {
10         Scanner cin = new Scanner(System.in);
11             BigInteger a = cin.nextBigInteger();
12             BigInteger b = cin.nextBigInteger();
13             BigInteger ans = a.multiply(b);
14             System.out.println(ans);
15     }
16 }

 

大数相减：public BigInteger subtract(BigInteger val)

大数相除：public BigInteger divide(BigInteger val)

 

大数阶乘：

 1 //JAVA 大数阶乘 
 2 import java.io.*;
 3 import java.math.BigInteger;
 4 import java.util.*;
 5 
 6 public class Main
 7 {
 8     public static void main(String args[])
 9     {
10         Scanner cin = new Scanner(System.in);    
11         int n = cin.nextInt(); //输入int型 
12         BigInteger ans = BigInteger.ONE;
13         for(int i = 1; i <= n; i++)
14         ans = ans.multiply(BigInteger.valueOf(i));
15         System.out.println(ans);
16     }
17 }

 

大数比较大小

 1 //JAVA 大数比较大小 
 2 import java.io.*;
 3 import java.math.BigInteger;
 4 import java.util.*;
 5 
 6 public class Main
 7 {
 8     public static void main(String args[])
 9     {
10         Scanner cin = new Scanner(System.in);    
11         while(cin.hasNext())
12         {
13             BigInteger a = cin.nextBigInteger();
14             BigInteger b = cin.nextBigInteger();
15             if(a.equals(BigInteger.ZERO) && b.equals(BigInteger.ZERO)) break;
16             int flag = a.compareTo(b);
17             if(flag == -1)
18                 System.out.println("a<b");
19             else if(flag == 0)
20                 System.out.println("a==b");
21             else
22                 System.out.println("a>b");
23         }
24     }
25 }

 

高精度幂

 1 //JAVA 高精度幂 
 2 import java.io.*;
 3 import java.math.BigDecimal;
 4 import java.util.*;
 5 
 6 public class Main
 7 {
 8     public static void main(String args[])
 9     {
10         Scanner cin = new Scanner(System.in);    
11         while(cin.hasNext())
12         {
13             BigDecimal ans = cin.nextBigDecimal();
14             int n = cin.nextInt();
15             String res = ans.pow(n).stripTrailingZeros().toPlainString(); //整数去掉后面的0和小数点 
16             if(res.startsWith("0")) //去掉前导0 
17             {
18                 res = res.substring(1);
19             }
20             System.out.println(res);
21         }
22     }
23 }

//这里的BigDecimal相当于double，但是精度更高