Cod sursa(job #3038438)
Utilizator | Data | 27 martie 2023 13:12:20 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva educationala | Marime | 0.47 kb |
#include <fstream>
#include <bitset>
using namespace std;
ifstream cin("ciur.in");
ofstream cout("ciur.out");
int n;
bitset<1000010> ciur;
int nr;
void eratostene()
{
nr++;
for(int i=2;i<=n;i++)
if(ciur[i]==0)
{
nr++;
int ratio=2*i-1;
for(int j=i+ratio;j<=n;j=j+ratio)
ciur[j]=1;
}
}
int main()
{
cin>>n;
if(n%2==1)
n++;
n=n/2;
eratostene();
cout<<nr;
return 0;
}