Cod sursa(job #1382473)
Utilizator | Data | 9 martie 2015 08:44:13 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.4 kb |
#include<fstream>
using namespace std;
ifstream f("ciur.in");
ofstream g("ciur.out");
int sol,i,j,n;
bool v[2000001];
int main()
{
f>>n;
sol=n-1;
for(i=2;i<=n;++i)
if(!v[i])
for(j=2;i*j<=n;++j)
if(!v[i*j])
{
v[i*j]=1,sol--;
// g<<i*j<<'\n';
}
// for(i=1;i<=n;++i) g<<i<<" "<<v[i]<<'\n';
g<<sol<<'\n';
return 0;
}