Iccanobif primes: Difference between revisions
Added C++ solution
(→J: fix wrong result) |
(Added C++ solution) |
||
Line 473:
<pre>
Same as Wren example.
</pre>
=={{header|C++}}==
{{libheader|GMP}}
<syntaxhighlight lang="cpp">#include <algorithm>
#include <iomanip>
#include <iostream>
#include <string>
#include <gmpxx.h>
using big_int = mpz_class;
bool is_probably_prime(const big_int& n) {
return mpz_probab_prime_p(n.get_mpz_t(), 15) != 0;
}
big_int reverse(const big_int& n) {
auto str = n.get_str();
std::reverse(str.begin(), str.end());
return big_int(str, 10);
}
std::string to_string(const big_int& num, size_t max_digits) {
std::string str = num.get_str();
size_t len = str.size();
if (len > max_digits) {
str = str.substr(0, max_digits / 2) + "..." +
str.substr(len - max_digits / 2);
str += " (";
str += std::to_string(len);
str += " digits)";
}
return str;
}
int main() {
big_int f0 = 0, f1 = 1;
std::cout << "First 30 Iccanobif primes:\n";
for (int count = 0; count < 30;) {
big_int f = f0 + f1;
auto p = reverse(f);
if (is_probably_prime(p)) {
++count;
std::cout << std::setw(2) << count << ": " << to_string(p, 40)
<< '\n';
}
f0 = f1;
f1 = f;
}
}</syntaxhighlight>
{{out}}
<pre>
First 30 Iccanobif primes:
1: 2
2: 3
3: 5
4: 31
5: 43
6: 773
7: 7951
8: 64901
9: 52057
10: 393121
11: 56577108676171
12: 940647607443258103531
13: 5237879497657222310489731409575442761
14: 9026258083384996860449366072142307801963
15: 19900335674812302969...34431012073266446403 (80 digits)
16: 77841137362967479985...52312097783685331923 (104 digits)
17: 37722585901567604188...29174997072830756131 (137 digits)
18: 75736193894876131595...50767238644714305761 (330 digits)
19: 17890336847332837620...13175300695235035913 (406 digits)
20: 92327163101729115305...27061468856047302507 (409 digits)
21: 50420157810698056253...67335124247362214481 (503 digits)
22: 30511012474739380092...69296158361330018201 (888 digits)
23: 46818547042693694555...08664543144645856321 (1020 digits)
24: 87101347853037819884...20128396998865227391 (1122 digits)
25: 17451656022543765336...20100243761843652461 (1911 digits)
26: 48989340566288399474...02930339234215909399 (1947 digits)
27: 12746927684958209654...53436989647994940101 (2283 digits)
28: 35746826582658751012...25010735912438195633 (3727 digits)
29: 87987175281297657706...48748727893681871587 (4270 digits)
30: 81807376367113798363...13687506007959668569 (10527 digits)
</pre>
| |||