Cod sursa(job #1827889)
Utilizator | Isac Lucian IsacLucian | Data | 12 decembrie 2016 14:35:05 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.42 kb |
#include <bits/stdc++.h>
using namespace std;
bitset<2000003>a;
int main()
{
int n,i,j,cnt=0;
ifstream fin("ciur.in");
ofstream fout("ciur.out");
fin>>n;
a[1]=1;
for(i=2;i*i<=n;i++)
if(a[i]==0)
for(j=i*i;j<=n;j+=i)
a[j]=1;
for(i=2;i<=n;i++)
if(a[i]==0)cnt++;
fout<<cnt<<"\n";
fin.close();
fout.close();
return 0;
}