Cod sursa(job #2380741)
Utilizator | Data | 15 martie 2019 14:41:33 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 30 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva educationala | Marime | 0.44 kb |
#include<bits/stdc++.h>
using namespace std;
ifstream in("ciur.in");
ofstream out("ciur.out");
bool v[2000000];
int main()
{
int N,x,i,j,contor=0;
in>>N;
for(i=3;i<=N;i+=2)
{
for(j=i*i;j<=N;j+=i)
{
v[j]=1;
}
}
for(i=2;i<=N;i++)
{
if(i>2 && i%2==0)
v[i]=1;
if(v[i]==0)
contor++;
}
out<<contor;
return 0;
}