Cod sursa(job #2471837)
Utilizator | Data | 11 octombrie 2019 16:52:27 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 70 |
Compilator | cpp-64 | Status | done |
Runda | basic_stuff | Marime | 0.46 kb |
#include <bits/stdc++.h>
using namespace std;
ifstream fin("ciur.in");
ofstream fout("ciur.out");
int v[20000001];
int main()
{
int n;
fin>>n;
int i,j;
for(i=2; i<=n; i++)
v[i]=1;
for(i=2; i<=sqrt(n); i++)
{
if(v[i])
{
for(j=i; j<=n/i; j++)
v[i*j]=0;
}
}
int cnt=0;
for(i=2; i<=n; i++)
if(v[i]==1) cnt++;
fout<<cnt;
return 0;
}