Cod sursa(job #1424445)
Utilizator | Data | 24 aprilie 2015 13:17:37 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.52 kb |
#include <iostream>
#include <deque>
#include <vector>
#include <cstring>
#include <algorithm>
using namespace std;
int N, compus[2000010], i, j, sol;
int main()
{
freopen("ciur.in","r",stdin);
freopen("ciur.out","w",stdout);
scanf("%d", &N);
sol = 1;
for(i = 3; i <= N; i+=2)
{
if(compus[i] == 0)
{
sol = sol + 1;
if(i > 2000)continue;
for(j = i * i ; j <= N; j+=i)
compus[j] = 1;
}
}
cout<<sol<<"\n";
return 0;
}