Basic usage of computing large numbers of Java BigInteger

Precision operational problems encountered in the programming contest, C ++ is not precision operational, only manually simulate artificial operation, manual high precision, while the java.mathpackage BigIntegerprovides basic arithmetic precision, so the race to solve common Java precision operational problems.

~~Of course, if the game supports pythonit when I did.~~

Create a BigInteger object

BigInteger class java.math.BigInteger package, the package is first referenced.

import java.math.BigInteger;

Create a BigInteger object

BigInteger a = new BigInteger("123"); // 这里是字符串

Change the value of the BigInteger

String str = "123";
BigInteger a = BigInteger.valueOf(str);

int num = 456;
BigInteger a = BigInteger.valueOf(num);

The basic constants

a = BigInteger.ONE // 1
b = BigInteger.TEN // 10
c = BigInteger.ZERO // 0

BigInteger input and output

Read directly into BigInteger

Scanner in = new Scanner(System.in); 
while(in.hasNext()) //等同于!=EOF
{
    BigInteger a;
    a = in.nextBigInteger();
    System.out.print(a.toString());
}

Indirect read BigInteger

Scanner in = new Scanner(System.in); 
while(in.hasNext()) //等同于!=EOF
{
    String s = in.nextLine();
    BigInteger a = new BigInteger(s);
    System.out.print(a.toString());
}

BigInteger direct output

System.out.print(a);

String BigInteger converted to decimal notation

System.out.print(a.toString());

BigInteger converted into a binary representation of p String

int p = 2;
System.out.print(a.toString(p)); // 输出a的二进制

Length in binary BigInteger

BigInteger n = new BigInteger("12");
System.out.println(n.bitLength()); // 4

The basic operation of BigInteger

Comparison between the BigInteger

BigInteger a = new BigInteger("123");
BigInteger b = new BigInteger("456");

System.out.println(a.equals(b)); // a == b 时为 true 否则为 false

BigInteger a = new BigInteger("123");
BigInteger b = new BigInteger("456");

if(a.compareTo(b) == 0) System.out.println("a == b"); // a == b
else if(a.compareTo(b) > 0) System.out.println("a > b"); // a > b
else if(a.compareTo(b) < 0) System.out.println("a < b"); // a < b

addition

BigInteger a = new BigInteger("123");
BigInteger b = new BigInteger("456");

a.add(b);

Subtraction

BigInteger a = new BigInteger("123");
BigInteger b = new BigInteger("456");

a.subtract(b);

multiplication

BigInteger a = new BigInteger("123");
BigInteger b = new BigInteger("456");

a.multiply(b);

division

BigInteger a = new BigInteger("123");
BigInteger b = new BigInteger("456");

a.divide(b);

Remainder

BigInteger a = new BigInteger("123");
BigInteger b = new BigInteger("456");

BigInteger c = b.remainder(a);
System.out.println(c);

Modulo division

BigInteger a = new BigInteger("123");
BigInteger b = new BigInteger("456");

BigInteger result[] = b.divideAndRemainder(a); // 该函数返回的是数组
System.out.println("商是：" + result[0] + "；余数是：" + result[1]);

Greatest common divisor

BigInteger a = new BigInteger("12");
BigInteger b = new BigInteger("56");
        
System.out.println(a.gcd(b)); // 4

Absolute value

BigInteger a = new BigInteger("-12");
        
System.out.println(a.abs()); // 12

Invert number

BigInteger a = new BigInteger("-12");
        
System.out.println(a.negate()); // 12

power

BigInteger a = new BigInteger("2");
        
System.out.println(a.pow(3)); // 8