Cod sursa(job #1635488)
Utilizator | Data | 6 martie 2016 18:10:03 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 20 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.5 kb |
#include <iostream>
#include <fstream>
using namespace std;
int main()
{
ifstream f("ciur.in");
ofstream g("ciur.out");
int ciur[20000],i,j,nr=0;
long long n;
f>>n;
for(i=2;i<=n;i++){
ciur[i]=1;
}
for(i=2;i*i<=n;i++){
if(ciur[i]==1){
for(j=2;j*i<=n;j++){
ciur[i*j]=0;
}
}
}
for(i=2;i<=n;i++){
if(ciur[i]==1){
nr++;
}
}
g<<nr;
return 0;
}