Prime triangle: Difference between revisions

{{works with|ALGOL 68G|Any - tested with release 2.8.3.win32}}

As Algol 68G under Windows is fully interpreted, a reduced number of rows is produced.

INT max number = 18; # largest number we will consider #

# construct a primesieve and from that a table of pairs of numbers whose sum is prime #

OD;

print( ( newline ) )

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<pre>

=={{header|C}}==

#include <stdbool.h>

#include <stdio.h>

printf("\nElapsed time: %f seconds\n", duration);

return 0;

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Number combinations are all stored in bit positions here. The <code>bpos()</code> functions returns the position index of the least significant bit in an integer. This code gains some speed, at the cost of total loss of readability. On the plus side, it has some bit manipulation tricks that may be interesting to some.

#include <stdint.h>

return 0;

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<pre> 1 2

=={{header|C++}}==

#include <chrono>

#include <iomanip>

std::chrono::duration<double> duration(end - start);

std::cout << "\nElapsed time: " << duration.count() << " seconds\n";

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=={{header|F_Sharp|F#}}==

This task uses [http://www.rosettacode.org/wiki/Extensible_prime_generator#The_functions Extensible Prime Generator (F#)]

// Prime triangle. Nigel Galloway: April 12th., 2022

let fN i (g,(e,l))=e|>Seq.map(fun n->let n=i n in (n::g,List.partition(i>>(=)n) l))

{2..20}|>Seq.iter(fun n->(primeT>>Seq.head>>List.iter(printf "%3d"))n;printfn "");;

{2..20}|>Seq.iter(primeT>>Seq.length>>printf "%d "); printfn ""

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<pre>

Takes about 0.64 seconds.

{{trans|Phix}}

import "fmt"

}

fmt.Println()

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Implementation:

Task example (displaying counts of number of valid sequences to the left, because that looks nice):

for_j.2}.i.1+y do.

N=. #seqs=. prime_pair_seqs j

155464 | 1 16 15 14 17 12 11 8 9 10 13 6 7 4 3 2 5 18

480728 | 1 18 13 16 15 14 17 12 11 8 9 10 7 6 5 2 3 4 19

=={{header|Java}}==

public static void main(String[] args) {

long start = System.currentTimeMillis();

return ((1L << n) & 0x28208a20a08a28acL) != 0;

}

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=={{header|Julia}}==

=== Filter method ===

function primetriangle(nrows::Integer)

@time primetriangle(16)

<pre>

1 2

=== Generator method ===

Similar to the Phix entry.

function solverow(row, pos, avail)

println(" 1 2\n" * prod(rowstrings), "\n", counts)

end

<pre>

1 2

=={{header|Mathematica}}/{{header|Wolfram Language}}==

FindPrimeTriangles[max_] :=

Module[{count = 0, firstsolution, primes, primeQ},

count

]

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<pre>{1,2}

{{trans|Raku}}

{{libheader|ntheory}}

use warnings;

use feature 'say';

}

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<pre>1 2

{{libheader|Phix/online}}

Not sure this counts as particularly clever but by the sound of things it's quite a bit faster than the other entries so far. &#128526;<br> You can run this online [http://phix.x10.mx/p2js/prime_triangles.htm here] (expect a blank screen for about 24s).

<span style="color: #008080;">with</span> <span style="color: #008080;">javascript_semantics</span>

<span style="color: #004080;">atom</span> <span style="color: #000000;">t0</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">time</span><span style="color: #0000FF;">()</span>

<span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"%s\n"</span><span style="color: #0000FF;">,</span><span style="color: #7060A8;">join</span><span style="color: #0000FF;">(</span><span style="color: #000000;">res</span><span style="color: #0000FF;">,</span><span style="color: #000000;">fmt</span><span style="color: #0000FF;">:=</span><span style="color: #008000;">"%d"</span><span style="color: #0000FF;">))</span>

<span style="color: #0000FF;">?</span><span style="color: #7060A8;">elapsed</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">time</span><span style="color: #0000FF;">()-</span><span style="color: #000000;">t0</span><span style="color: #0000FF;">)</span>

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<pre>

Limit the upper threshold a bit to avoid multiple hours of pointless calculations. Even just up to 17 takes over 20 minutes.

my $lock = Lock.new;

put (1,2);

}

}

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<pre>1 2

=={{header|Rust}}==

assert!(n < 64);

((1u64 << n) & 0x28208a20a08a28ac) != 0

let time = start.elapsed();

println!("\nElapsed time: {} milliseconds", time.as_millis());

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=={{header|Swift}}==

func isPrime(_ n: Int) -> Bool {

let endTime = CFAbsoluteTimeGetCurrent()

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=={{header|Visual Basic .NET}}==

{{Trans|ALGOL 68}}

Option Explicit On

End Sub

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<pre>

{{libheader|Wren-fmt}}

Takes around 18.7 seconds which is fine for Wren.

var canFollow = []

}

System.print()

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