Cod sursa(job #403847)
Utilizator | Data | 25 februarie 2010 14:05:01 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.29 kb |
#include<fstream>
using namespace std;
int main(){
ifstream fin("ciur.in");
ofstream fout("ciur.out");
char v[2000001]={0};
int i,n,j,k=0;
fin>>n;
for(i=2;i*i<=n;i++)
if(!v[i])
for(j=2;j*i<=n;j++)
v[j*i]=1;
for(i=2;i<=n;i++)
k+=1-v[i];
fout<<k;
return 0;
}