Question

Urgent! Cum aflu numerele prime cu ciurul lui eratostene!

Answer 1

#include <iostream>

#include <fstream>

#define NN 1000000

using namespace std;

ifstream fin("eratostene.in");

ofstream fout("eratostene.out");

int n, v[NN];

int main(){

v[0] = v[1] = 1;

for(int i=2;i*i<NN; ++i)

if(v[i]==0)

for(int j=2;i*j<NN;++j)

v[i*j] = 1;

fin >> n;

int x,C = 0;

for(int i=1;i<=n;++i){

fin >> x;

if(v[x]==0)

C ++;

}

fout << C;

return 0;

}