Cod sursa(job #1370946)
Utilizator | Soare Roxana Florentina roxana_97 | Data | 3 martie 2015 18:15:02 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.48 kb |
#include<fstream>
#include<bitset>
#define Nmax 2000099
using namespace std;
ifstream f("ciur.in");
ofstream g("ciur.out");
int n,k,p[200009];
bitset <Nmax> b;
int main()
{
f>>n;
k=1;
p[k]=2;
for(int i=4;i<=n;i+=2)
b[i]=1;
for(int i=3;i<=n;i+=2)
if(b[i]==0)
{
++k;
p[k]=i;
for(int j=2*i;j<=n;j+=i) b[j]=1;
}
g<<k<<'\n';
f.close();g.close();
return 0;
}