Cod sursa(job #1930114)
Utilizator | Data | 18 martie 2017 15:26:53 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.36 kb |
#include <fstream>
using namespace std;
ifstream in("ciur.in");
ofstream out("ciur.out");
int i,j,n;
bool v[2000001];
void ciur()
{
v[1]=1;
for(i=1;i<=n;i++)
if(v[i]==0)
for(j=i*2;j<=n;j+=i)
v[j]=1;
}
int main()
{
in>>n;
int cnt=0;
ciur();
for(i=1;i<=n;i++)
if(v[i]==0)
cnt++;
out<<cnt;
return 0;
}