Honaker primes: Difference between revisions
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(New post without using external libraries, in addition to an existing post which uses the "Primesieve" lexternal ibrary.) |
m (Minor code improvement.) |
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import java.util.ArrayList; |
import java.util.ArrayList; |
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import java.util.List; |
import java.util.List; |
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import java.util.stream.Collectors; |
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import java.util.stream.IntStream; |
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public final class HonakerPrimes { |
public final class HonakerPrimes { |
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private static int digitalSum(int number) { |
private static int digitalSum(int number) { |
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return String.valueOf(number).chars().map( i -> i - (int) '0' ).sum(); |
return String.valueOf(number).chars().map( i -> i - (int) '0' ).sum(); |
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} |
} |
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| ⚫ | |||
private static void sievePrimes(int limit) { |
private static void sievePrimes(int limit) { |
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List<Boolean> markedPrime = IntStream.range(0, limit).boxed().map( i -> true ).collect(Collectors.toList()); |
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final int halfLimit = ( limit + 1 ) / 2; |
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boolean[] composite = new boolean[halfLimit]; |
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if ( markedPrime.get(p) ) { |
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for ( int i = 1, p = 3; i < halfLimit; p += 2, i++ ) { |
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if ( ! composite[i] ) { |
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markedPrime.set(i, false); |
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primes.add(p); |
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} |
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for ( int a = i + p; a < halfLimit; a += p ) { |
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composite[a] = true; |
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} |
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} |
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} |
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primes = new ArrayList<Integer>(); |
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} |
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for ( int p = 2; p < limit; p++ ) { |
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if ( markedPrime.get(p) ) { |
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} |
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} |
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} |
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private static int honakerIndex = 0; |
private static int honakerIndex = 0; |
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private static int primeIndex = 0; |
private static int primeIndex = 0; |
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private static List<Integer> primes; |
private static List<Integer> primes = new ArrayList<Integer>(); |
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private static record HonakerPrime(int honakerIndex, int primeIndex, int prime) { |
private static record HonakerPrime(int honakerIndex, int primeIndex, int prime) { |
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