Cod sursa(job #1355755)
Utilizator | Data | 22 februarie 2015 22:44:29 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.52 kb |
#include <cstdio>
using namespace std;
const int MAX_N = 2000000;
FILE *in, *out;
bool ciur[MAX_N+1];
int main()
{
in = fopen("ciur.in", "r");
out = fopen("ciur.out", "w");
int n;
long long nr = 0;
fscanf(in, "%d", &n);
for(int i = 2; i <= n; i++)
{
if(!ciur[i])
{
nr++;
for(int j = i+i; j <= n; j += i)
ciur[j] = true;
}
}
fprintf(out, "%lld", nr);
fclose(in);
fclose(out);
return 0;
}