31 lines
630 B
C++
31 lines
630 B
C++
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#include "util.h"
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/* some helper functions */
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auto is_prime(ull n) -> bool {
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static std::unordered_map<ull, bool> primes;
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if (n < 2) {
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primes[n] = false;
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return false;
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}
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if (primes.count(n) > 0) {
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return primes[n];
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}
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for (int i = 2; i * i <= n; i+=2) {
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if (n % i == 0) {
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primes[n] = false;
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return false;
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}
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if (i == 2) i--;
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}
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primes[n] = true;
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return true;
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}
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auto print_vec(std::vector<ull> vec) -> void {
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std::cout << '[';
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for (ull val : vec) {
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std::cout << val << ", ";
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}
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std::cout << "]\n";
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}
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