34 lines
836 B
C++
34 lines
836 B
C++
#include <gmpxx.h>
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#include <primesieve.hpp>
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#include <iostream>
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using big_int = mpz_class;
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std::string to_string(const big_int& num, size_t n) {
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std::string str = num.get_str();
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size_t len = str.size();
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if (len > n) {
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str = str.substr(0, n / 2) + "..." + str.substr(len - n / 2);
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str += " (";
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str += std::to_string(len);
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str += " digits)";
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}
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return str;
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}
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bool is_probably_prime(const big_int& n) {
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return mpz_probab_prime_p(n.get_mpz_t(), 25) != 0;
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}
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int main() {
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const big_int one(1);
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primesieve::iterator pi;
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pi.next_prime();
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for (int i = 0; i < 24;) {
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uint64_t p = pi.next_prime();
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big_int n = ((one << p) + 1) / 3;
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if (is_probably_prime(n))
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std::cout << ++i << ": " << p << " - " << to_string(n, 30) << '\n';
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}
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}
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