Prime算法

#include <iostream>#include <cmath>using namespace std;void prime(bool a[], const int n);int main(){int n;bool a[1000000];cin >> n;prime(a,n);for(int i=0;i<n;i++)if(a[i] == true)cout << i << " ";cout << endl;return 0;}void prime(bool a[], const int n){//Àÿ ˝…∏—°∑®int i, j;//∆Ê ˝±ÍŒ™true£¨≈º ˝±ÍŒ™falsea[0] = false;a[1] = false;a[2] = true;for( i=3; i<n;i+=2){a[i] = true;a[i+1] = false;}//…∏—°for( i=3; i<=sqrt(n); i+=2 )    {if(a[i] == true) for( j=i+i; j<=n; j+=i )a[j] = false;}}