Cod sursa(job #688361)
Utilizator | Stefania Aungurencei stefaniaa | Data | 23 februarie 2012 15:06:45 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 40 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.35 kb |
#include <fstream>
using namespace std;
ifstream f("ciur.in");
ofstream g("ciur.out");
long n,i,k,j;
char v[2000003];
void init()
{
for (i=1;i<=n;i++)
v[i]='*';
}
int main()
{
f>>n;
init();
v[1]=0;
for (i=2;i<=n;i++)
for (j=2*i;j<=n;j+=i)
v[j]='\0';
k=0;
for(i=1;i<=n;i++) if (v[i]=='*') k++;
g<<k<<'\n';
return 0;
}