Cod sursa(job #1884709)
Utilizator | Data | 19 februarie 2017 01:29:39 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.43 kb |
//Ciur.cpp
#include <fstream>
#include <iostream>
using namespace std;
ifstream fin("ciur.in");
ofstream fout("ciur.out");
bool prim[2000001];
int main()
{
int n, cnt = 0;
fin >> n;
for (int i = 2; i <= n; ++i)
prim[i] = true;
for(int i = 2; i * i <= n; ++i)
if(prim[i])
for(int j = 2; j * i <= n; ++j)
prim[i * j] = false;
for (int i = 2; i <= n; ++i)
if(prim[i])
cnt ++;
fout << cnt;
}