Cod sursa(job #1423276)
Utilizator | Karla Maria karla | Data | 21 aprilie 2015 17:27:56 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.5 kb |
#include <stdio.h>
#include <math.h>
using namespace std;
FILE*f=fopen("ciur.in","r"),*g=fopen("ciur.out","w");
int n, v[2000009], sol;
void ciur()
{
for(int i = 2; i < sqrt(n); i++)
{
if(v[i] == 0)
{
int j = 2*i;
while(j <= n)
v[j] = 1, j += i;
}
}
}
int main()
{
fscanf(f,"%d",&n);
ciur();
for(int i = 2; i <= n; i++)
if(v[i] == 0) sol++;
fprintf(g,"%d ",sol);
return 0;
}