Cod sursa(job #2872889)
Utilizator | Filip Gruianu Filipppp | Data | 18 martie 2022 08:57:38 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva educationala | Marime | 0.58 kb |
#include <iostream>
using namespace std;
const int N=2000000+2;
bool v[N];
int main()
{
freopen ("ciur.in", "r", stdin);
freopen ("ciur.out", "w", stdout);
int n,p=0;
cin>>n;
v[2] = 1;
for (int i=3;i<=n;i+=2)
{
v[i] = 1;
}
for (int i=3;i<=n;i+=2)
{
if (v[i] == 1)
{
for (int j=3*i;j<=n;j+=2*i)
{
v[j] = 0;
}
}
}
for (int i=2;i<=n;i++)
{
if (v[i] == 1)
{
p++;
}
}
cout<<p;
}