Cod sursa(job #2526952)
Utilizator | Data | 19 ianuarie 2020 13:21:25 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva educationala | Marime | 0.39 kb |
#include <fstream>
using namespace std;
ifstream in("ciur.in");
ofstream out("ciur.out");
bool a[2000001];
int main()
{
int n,i,j,s=1;
in>>n;
for(i=4;i<=n;i+=2)
{
a[i]=1;
}
for(i=3;i<=n;i+=2)
{
if(a[i]==0)
for(j=2;i*j<=n;j++)
a[i*j]=1;
}
for(i=3;i<=n;i+=2)
{if(a[i]==0)
s++;}
out<<s;
}