筛素数

#include<iostream>#include<cstdio>#include<cstring>#include<cmath>using namespace std;int a[105];int n;void init(){    int m = sqrt(n+0.5);    for(int i = 2;i <= m;i++)        if(!a[i])//a[i]为质数！    {        for(int j = i*i;j <= 100;j+=i)            a[j] = 1;    }    return;}int main(){    cin >> n;    init();    for(int i = 2;i <= 100;i++)        if(!a[i])        cout << i << endl;    return 0;}