数论专题小结：素数筛法

Eratothenes筛法

注：时间复杂度为O(N*logN)。

#define N 1000int vis[N];vector<int>primes;void init()//一般用于打表{int m = sqrt(N + 0.5);for (int i = 2; i <= m;i++)if (!vis[i])for (int j = i*i; j <= N; j += i)vis[j] = 1;for (int i = 2; i <= N;i++)if (!vis[i])primes.push_back(i);}