Cod sursa(job #1696856)
| Utilizator |  Gabi Tulba-Lecu GabiTulba |
Data | 30 aprilie 2016 01:02:18 |
|---|---|---|---|
| Problema | Ciurul lui Eratosthenes | Scor | 100 |
| Compilator | cpp | Status | done |
| Runda | Arhiva educationala | Marime | 0.25 kb |
#include <fstream>
#include <bitset>
using namespace std;
ifstream f("ciur.in");ofstream g("ciur.out");
int n,x=1,i,j;bitset<2000001>p;
int main(){f>>n;
for(i=3;i*i<=n;i+=2)if(!p[i])for(j=i*i;j<=n;j+=2*i)p[j]=1;
g<<(n+1)/2-p.count();
return 0;}