Ormiston triples: Difference between revisions
→{{header|Wren}}: Like Phix, added a faster version using 'primesieve'.
m (→faster version (win64 only): oops, it was collecting the middle primes) |
(→{{header|Wren}}: Like Phix, added a faster version using 'primesieve'.) |
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4,925 Ormiston triples before 10,000,000,000
</pre>
===Faster version===
{{libheader|wren-psieve}}
This uses our bindings to the C++ library, primesieve and, as we're now iterating through the primes rather than sieving for them, uses very little memory compared to the first version.
It's also far quicker - 4.4 seconds to search up to 1 billion and 43.4 seconds to search up to 10 billion.
<syntaxhighlight lang="ecmascript">import "./psieve" for Primes
import "./math" for Int
import "./fmt" for Fmt
var limit = 1e10
var digitPrimes = Int.primeSieve(30)
var it = Primes.iter()
var orm25 = []
var j = limit/10
var count = 0
var counts = []
var p1 = it.next
var p2 = it.next
var p3 = it.next
while (true) {
p1 = p2
p2 = p3
p3 = it.next
if ((p2 - p1) % 18 != 0 || (p3 - p2) % 18 != 0) continue
var key1 = 1
for (dig in Int.digits(p1)) key1 = key1 * digitPrimes[dig]
var key2 = 1
for (dig in Int.digits(p2)) key2 = key2 * digitPrimes[dig]
if (key1 != key2) continue
var key3 = 1
for (dig in Int.digits(p3)) key3 = key3 * digitPrimes[dig]
if (key2 == key3) {
if (count < 25) orm25.add(p1)
if (p1 >= j) {
counts.add(count)
if (j == limit) break
j = j * 10
}
count = count + 1
}
}
System.print("Smallest members of first 25 Ormiston triples:")
Fmt.tprint("$,10d ", orm25, 5)
System.print()
j = limit/10
for (i in 0...counts.count) {
Fmt.print("$,d Ormiston triples before $,d", counts[i], j)
j = j * 10
System.print()
}</syntaxhighlight>
{{out}}
<pre>
Same as first version.
</pre>
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