Consecutive primes with ascending or descending differences: Difference between revisions
Consecutive primes with ascending or descending differences (view source)
Revision as of 10:48, 3 April 2021
, 3 years agoAdded Rust solution
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(Added Rust solution) |
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8 was the longest run of consecutive primes whose differences between primes are strictly descending and < 1,000,000
</pre>
=={{header|Rust}}==
<lang rust>// [dependencies]
// primal = "0.3"
fn print_diffs(vec: Vec<usize>) {
for i in 0..vec.len() {
if i > 0 {
print!(" ({}) ", vec[i] - vec[i - 1]);
}
print!("{}", vec[i]);
}
println!();
}
fn main() {
let limit = 1000000;
let mut asc = Vec::new();
let mut desc = Vec::new();
let mut max_asc = Vec::new();
let mut max_desc = Vec::new();
let mut max_asc_len = 0;
let mut max_desc_len = 0;
for p in primal::Sieve::new(limit)
.primes_from(2)
.take_while(|x| *x < limit)
{
let alen = asc.len();
if alen > 1 && p - asc[alen - 1] <= asc[alen - 1] - asc[alen - 2] {
asc = asc.split_off(alen - 1);
}
asc.push(p);
if asc.len() >= max_asc_len {
if asc.len() > max_asc_len {
max_asc_len = asc.len();
max_asc.clear();
}
max_asc.push(asc.clone());
}
let dlen = desc.len();
if dlen > 1 && p - desc[dlen - 1] >= desc[dlen - 1] - desc[dlen - 2] {
desc = desc.split_off(dlen - 1);
}
desc.push(p);
if desc.len() >= max_desc_len {
if desc.len() > max_desc_len {
max_desc_len = desc.len();
max_desc.clear();
}
max_desc.push(desc.clone());
}
}
println!("Longest run(s) of ascending prime gaps up to {}:", limit);
for v in max_asc {
print_diffs(v);
}
println!("\nLongest run(s) of descending prime gaps up to {}:", limit);
for v in max_desc {
print_diffs(v);
}
}</lang>
{{out}}
<pre>
Longest run(s) of ascending prime gaps up to 1000000:
128981 (2) 128983 (4) 128987 (6) 128993 (8) 129001 (10) 129011 (12) 129023 (14) 129037
402581 (2) 402583 (4) 402587 (6) 402593 (8) 402601 (12) 402613 (18) 402631 (60) 402691
665111 (2) 665113 (4) 665117 (6) 665123 (8) 665131 (10) 665141 (12) 665153 (24) 665177
Longest run(s) of descending prime gaps up to 1000000:
322171 (22) 322193 (20) 322213 (16) 322229 (8) 322237 (6) 322243 (4) 322247 (2) 322249
752207 (44) 752251 (12) 752263 (10) 752273 (8) 752281 (6) 752287 (4) 752291 (2) 752293
</pre>
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