De Polignac numbers: Difference between revisions
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273421</syntaxhighlight> |
273421</syntaxhighlight> |
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(We use 999 here for the 1000th number because 0 is the first J index.) |
(We use 999 here for the 1000th number because 0 is the first J index.) |
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=={{header|Java}}== |
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<syntaxhighlight lang="java"> |
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public final class DePolignacNumbers { |
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public static void main(String[] args) { |
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System.out.println("The first 50 de Polignac numbers:"); |
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for ( int n = 1, count = 0; count < 10_000; n += 2 ) { |
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if ( isDePolignacNumber(n) ) { |
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count += 1; |
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if ( count <= 50 ) { |
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System.out.print(String.format("%5d%s", n, ( count % 10 == 0 ? "\n" : " ") )); |
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} else if ( count == 1_000 ) { |
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System.out.println(); |
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System.out.println("The 1,000th de Polignac number: " + n); |
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} else if ( count == 10_000 ) { |
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System.out.println(); |
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System.out.println("The 10,000th de Polignac number: " + n); |
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} |
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} |
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} |
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} |
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private static boolean isDePolignacNumber(int number) { |
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for ( int p = 1; p < number; p <<= 1 ) { |
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if ( isPrime(number - p) ) { |
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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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private static boolean isPrime(int number) { |
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if ( number < 2 ) { |
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return false; |
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} |
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if ( number % 2 == 0 ) { |
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return number == 2; |
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} |
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if ( number % 3 == 0 ) { |
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return number == 3; |
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} |
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int delta = 2; |
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int k = 5; |
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while ( k * k <= number ) { |
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if ( number % k == 0 ) { |
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return false; |
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} |
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k += delta; |
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delta = 6 - delta; |
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} |
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return true; |
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} |
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} |
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</syntaxhighlight> |
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{{ out }} |
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<pre> |
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The first 50 de Polignac numbers: |
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1 127 149 251 331 337 373 509 599 701 |
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757 809 877 905 907 959 977 997 1019 1087 |
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1199 1207 1211 1243 1259 1271 1477 1529 1541 1549 |
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1589 1597 1619 1649 1657 1719 1759 1777 1783 1807 |
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1829 1859 1867 1927 1969 1973 1985 2171 2203 2213 |
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The 1,000th de Polignac number: 31941 |
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The 10,000th de Polignac number: 273421 |
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</pre> |
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=={{header|jq}}== |
=={{header|jq}}== |
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