Consecutive primes with ascending or descending differences: Difference between revisions
Consecutive primes with ascending or descending differences (view source)
Revision as of 13:59, 3 April 2021
, 3 years agoAdded C++ solution
(Added Rust solution) |
(Added C++ solution) |
||
Line 166:
Descending, found run of 10 consecutive primes:
11938793 (60) 11938853 (38) 11938891 (28) 11938919 (14) 11938933 (10) 11938943 (8) 11938951 (6) 11938957 (4) 11938961 (2) 11938963</pre>
=={{header|C++}}==
{{libheader|Primesieve}}
<lang cpp>#include <cstdint>
#include <iostream>
#include <vector>
#include <primesieve.hpp>
void print_diffs(const std::vector<uint64_t>& vec) {
for (size_t i = 0, n = vec.size(); i != n; ++i) {
if (i != 0)
std::cout << " (" << vec[i] - vec[i - 1] << ") ";
std::cout << vec[i];
}
std::cout << '\n';
}
int main() {
std::cout.imbue(std::locale(""));
std::vector<uint64_t> asc, desc;
std::vector<std::vector<uint64_t>> max_asc, max_desc;
size_t max_asc_len = 0, max_desc_len = 0;
uint64_t prime;
const uint64_t limit = 1000000;
for (primesieve::iterator pi; (prime = pi.next_prime()) < limit; ) {
size_t alen = asc.size();
if (alen > 1 && prime - asc[alen - 1] <= asc[alen - 1] - asc[alen - 2])
asc.erase(asc.begin(), asc.end() - 1);
asc.push_back(prime);
if (asc.size() >= max_asc_len) {
if (asc.size() > max_asc_len) {
max_asc_len = asc.size();
max_asc.clear();
}
max_asc.push_back(asc);
}
size_t dlen = desc.size();
if (dlen > 1 && prime - desc[dlen - 1] >= desc[dlen - 1] - desc[dlen - 2])
desc.erase(desc.begin(), desc.end() - 1);
desc.push_back(prime);
if (desc.size() >= max_desc_len) {
if (desc.size() > max_desc_len) {
max_desc_len = desc.size();
max_desc.clear();
}
max_desc.push_back(desc);
}
}
std::cout << "Longest run(s) of ascending prime gaps up to " << limit << ":\n";
for (const auto& v : max_asc)
print_diffs(v);
std::cout << "\nLongest run(s) of descending prime gaps up to " << limit << ":\n";
for (const auto& v : max_desc)
print_diffs(v);
return 0;
}</lang>
{{out}}
<pre>
Longest run(s) of ascending prime gaps up to 1,000,000:
128,981 (2) 128,983 (4) 128,987 (6) 128,993 (8) 129,001 (10) 129,011 (12) 129,023 (14) 129,037
402,581 (2) 402,583 (4) 402,587 (6) 402,593 (8) 402,601 (12) 402,613 (18) 402,631 (60) 402,691
665,111 (2) 665,113 (4) 665,117 (6) 665,123 (8) 665,131 (10) 665,141 (12) 665,153 (24) 665,177
Longest run(s) of descending prime gaps up to 1,000,000:
322,171 (22) 322,193 (20) 322,213 (16) 322,229 (8) 322,237 (6) 322,243 (4) 322,247 (2) 322,249
752,207 (44) 752,251 (12) 752,263 (10) 752,273 (8) 752,281 (6) 752,287 (4) 752,291 (2) 752,293
</pre>
=={{header|Factor}}==
| |||