筛法求素数表

#include <cstdio>#include <cmath>#include <cstring>using namespace std;const int N = 10000;int vis[N];int prime[N];void primeTable(){        //int m = static_cast<int>(sqrt(0.5 + N));        int c = 0;        memset(vis, 0, sizeof(vis));        for(int i = 2; i < N; i++)        {                if(!vis[i])                {                        prime[c++] = i;                }                for(int j = i * i; j < N; j+=i)                {                        vis[j] = 1;                }        }        printf("table size : %d\n", c);        /*        for(int i = 0; i < c; i++)        {                if(i % 20 == 0)                {                        printf("\n");                }                printf("%d ", prime[i]);        }        printf("\n");        */}int main(){        primeTable();}

输出结果：

table size : 1229