27 lines
1.1 KiB
Java
27 lines
1.1 KiB
Java
import java.math.BigInteger;
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import java.util.Scanner;
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public class twinPrimes {
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public static void main(String[] args) {
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Scanner input = new Scanner(System.in);
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System.out.println("Search Size: ");
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BigInteger max = input.nextBigInteger();
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int counter = 0;
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for(BigInteger x = new BigInteger("3"); x.compareTo(max) <= 0; x = x.add(BigInteger.ONE)){
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BigInteger sqrtNum = x.sqrt().add(BigInteger.ONE);
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if(x.add(BigInteger.TWO).compareTo(max) <= 0) {
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counter += findPrime(x.add(BigInteger.TWO), x.add(BigInteger.TWO).sqrt().add(BigInteger.ONE)) && findPrime(x, sqrtNum) ? 1 : 0;
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}
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}
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System.out.println(counter + " twin prime pairs.");
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}
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public static boolean findPrime(BigInteger x, BigInteger sqrtNum){
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for(BigInteger divisor = BigInteger.TWO; divisor.compareTo(sqrtNum) <= 0; divisor = divisor.add(BigInteger.ONE)){
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if(x.remainder(divisor).compareTo(BigInteger.ZERO) == 0){
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return false;
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}
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}
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return true;
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}
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}
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