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