Cod sursa(job #1988488)
Utilizator | Data | 3 iunie 2017 10:17:30 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 0 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.51 kb |
#include <bits/stdc++.h>
using namespace std;
ifstream fin("ciur.in");ofstream fout("ciur.out");
int main()
{ const int Nmax=1000001;
bitset<Nmax>ciur;
ciur[1]=1;
for(int i=4;i<=Nmax;i+=2)
ciur[i]=1;
for(int i=3;i*i<=Nmax;i+=2){
if(ciur[i]==0)
for(int j=i*i;j<=Nmax;j=j+2*i){
ciur[j]=1;
}
}
int n,a,cnt=0;
fin>>n;
for(int i=2;i<=n;i++)
if(v[i]==0)
cnt++;
fout<<cnt;
return 0;
}