Cod sursa(job #701106)
Utilizator | Data | 1 martie 2012 13:38:40 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.27 kb |
#include<fstream>
using namespace std;
int main()
{ifstream f("ciur.in");
ofstream g("ciur.out");
int i,j,n,k=1;
f>>n;
char a[2000002];
for(i=1;i<=n;i++)
a[i]='0';
for(i=3;i<=n;i=i+2)
if(a[i]=='0')
{
for(j=i*i;j<=n;j=j+i)
a[j]='1';
k++;
}
g<<k;
return 0;
}