Cod sursa(job #2779586)

Utilizator BlaugranasEnal Gemaledin Blaugranas Data 4 octombrie 2021 11:51:47
Problema Ciurul lui Eratosthenes Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 0.3 kb
Raporteaza aceasta sursa 
#include<bits/stdc++.h>
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;
}