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c_cpp
4 years ago
603 B
5
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const int N = 1e5; // sieve prime, careful with int overflow vector <int> primes; vector <bool> isPrime(N + 5, true); void sieve() { isPrime[0] = isPrime[1] = false; for (int i = 4; i <= N; i += 2) { isPrime[i] = false; } for (int i = 3; i * i <= N; i += 2) { if (isPrime[i]) { for (int j = i * i; j <= N; j += i * 2) { isPrime[j] = false; } } } primes.push_back(2); for (int i = 3; i <= N; i += 2) { if (isPrime[i]) { primes.push_back(i); } } }
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