Cod sursa(job #2440024)
Utilizator | Data | 17 iulie 2019 13:54:25 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva educationala | Marime | 0.53 kb |
#include <iostream>
using namespace std;
bool prime[2000002];
int main()
{
int i, j, n, cnt = 0;
FILE *in, *out;
in = fopen("ciur.in", "r");
out = fopen("ciur.out", "w");
fscanf(in, "%d", &n);
for (i = 2; i*i <= n; i++){
if (prime[i] == 0){
for (j = i*i; j <= n; j += i){
prime[j] = 1;
}
}
}
for (i = 2; i <= n; i++){
if (prime[i] == 0){
cnt++;
}
}
fprintf(out, "%d", cnt);
return 0;
}