Cod sursa(job #3227307)
Utilizator | Data | 29 aprilie 2024 13:17:52 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 0 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva educationala | Marime | 0.44 kb |
#include <fstream>
#include <vector>
#include <algorithm>
using namespace std;
ifstream cin("ciur.in");
ofstream cout("ciur.out");
string cuv;
int ciur[2000001];
int main()
{
long long int N,cnt=0;
cin>>N;
for(int div=2;div*div<=N;div++)
if(ciur[div]==0)
{
for(int mult=2*div;mult<=N;mult+=div)
ciur[mult]=1;
cnt++;
}
cout<<cnt*2;
}