Cod sursa(job #792432)
Utilizator | Data | 27 septembrie 2012 10:50:22 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.51 kb |
#include<fstream>
#include<cstdio>
#define M 2000005
using namespace std;
int n, cont;
char p[M];
ifstream f("ciur.in");
FILE *g;
int main()
{
int i, j;
f>>n;//fscanf(f, "%d", &n);
f.close();
for(i=2; i<=n; i++)
p[i]='1';
for(i=2; i<=n; i++)
if(p[i]=='1')
{
cont++;
for(j=i; j<=n; j+=i)
p[j]='0';
}
g=fopen("ciur.out", "w");
fprintf(g, "%d\n", cont);
return 0;
}